Flowmaster has kicked off their Scavenger Series Elite Headers with offerings for both classic and late model musclecars from Chrysler, Ford, and General Motors. We recently had the opportunity to get a first-hand look at a sampling of these new headers, and installed a set to test out the fit and finish for ourselves. Follow along and get all the details as we review the new Flowmaster Scavenger Series Elite Headers.  

Features Across The Entire Line

All of Flowmaster’s Scavenger Series Elite Headers are made of thick 16-gauge stainless steel that is finished with high-temp ceramic coating.

Flowmaster’s Scavenger Series Elite Headers are high-quality in every way. For starters, there are no “universal” applications and every set of Flowmaster headers is designed for a specific application – which translates to easier installation, and no massaging or dinging them to make them fit your car.

Each set may be made specifically for one make and model, but regardless of the application all Flowmaster headers feature the same construction. The entire line of Scavenger series headers are constructed using thick 16-gauge 409S stainless steel, which not only resists corrosion but is also better at holding in high exhaust temperatures. Every set of Flowmaster headers is also ceramic coated for temperature control, and good looks as a fortunate side-effect.

Flowmaster added features to their headers like the collector velocity cone and 3/8-inch laser cut flanges that are usually only found on high-dollar custom race headers.

All of Flowmaster’s headers also feature 3/8-inch thick flanges on both the head and collector sides. “These flanges are essentially warp-free,” says Thomas. “You would have to get a 3/8-inch flange extremely hot to warp it.”

Another feature of the Scavenger Series headers is most models have a velocity spike inside the collector. “This serves two purposes,” says Thomas. “One, it strengthens the joint where all four primaries come together at the collector, and provides more weldable surface area. Secondly, the spike directs the exhaust gasses into the collector as they come out of each primary pipe.” Directing the exhaust pulses in this manner makes it much easier for them to follow each other along the exhaust tract, and actually increases the scavenging effect of the headers.  

Flowmaster headers typically have tuned length primaries and paired cylinders for entering the collector. They have all been engineered to enhance the performance of every application, both long-tubes for early musclecars or emissions compliant short-tube for a modern car.

These beasts are for a Big-Block equipped 1st Gen Camaro (Part #814111), and feature 1-3/4-inch primaries and 3-inch ball-socket collectors.

Scavenger Series Long-Tubes

Flowmaster’s Scavenger Series Elite long-tubes are designed for musclecar owners whose main concern is maximum power. Along with the 16-gauge construction, ceramic coating, and velocity spike, the long-tubes are built using hefty 1-5/8-inch, 1-3/4-inch, or 2-inch primaries. Many models also have Flowmaster’s 3-inch gasket-less ball-socket collector flanges, and as a nice bonus Flowmaster includes the reducer side of the connector as well. That makes for at least one less part for you to chase down before you can finish your install and hit the road. All you need is to install your headers, cut your existing exhaust, and weld it up to the flanges, bolt it up and be on your way.

CARB Certified Short-Tubes

There’s no getting around it. Emissions compliance is a very important consideration for owners of modern musclecars. For those who want more power but still want to keep their new ride emissions legal, Flowmaster also offers CARB certified 50-state legal shorties for many applications. Flowmaster’s shorties are direct replacements for restrictive exhaust manifolds, and bolt directly to your stock exhaust system.

Flowmaster is also offering CARB certified 50-state legal short-tube headers like these Shorties for 5th Gen Camaros (Part #814121). They have 1-3/4-inch primaries and 3-inch outlets that bolt directly to your stock exhaust system.

To get a CARB Certification, an aftermarket header cannot physically move any of the emissions equipment on the car. That means that header manufacturers cannot change the location of the catalytic converter on the car. “The outlet of the new header design has to be in the exact same place as the stock manifold,” says Thomas. “You have to work forward of that to design a set of shorties.”

Even so, every set of Flowmaster short-tubes have the same features and construction as the long-tubes, including the velocity spike, 3/8-inch and laser cut flanges, and mandrel bent primary tubes. “We’ve seen some impressive gains from the short-tube headers,” says Thomas. “Especially when you consider that you can install them yourself in just a few hours and bolt them right up to your existing exhaust.”  

Fox Body Mustang Flowmaster Shortie Install

We installed a set of Flowmaster’s direct replacement shorties on our supercharged Fox Body Mustang (Part #814221).

We installed a set of Flowmaster’s direct-fit Scavenger Series shorties (Part #814221) on one of our resident beasts of burden – a 1992 Fox Body Mustang. The car is still equipped with it’s original 42,000 mile 5.0L, but has been upgraded with an array of bolt-ons that include a Vortec T-Trim supercharger and a full Flowmaster 2.5-inch American Thunder exhaust system. The Mustang was originally a drag car that went as quick as 10.60 in the quarter, but we’ve recently been converting for road racing, complete with a Maximum Motorsports Grip Box suspension set up and a new Tremec T-56 Magnum 6-speed trans. 

The short-tube headers dropped right in place and bolted directly to the Flowmaster American Thunder exhaust system the car already had.

The Flowmaster shorties dropped right into place in the Mustang’s tight engine compartment and easily cleared all of the factory brackets, suspension, and steering components with no problem. Unlike some other header installs, we didn’t have to modify the Flowmaster Scavenger Series shorites to make them fit.

The collector flanges mated right up to the Flowmaster American Thunder exhaust downpipes, and the included hardware and correct gaskets just made things go even smoother.

The headers cleared everything just fine, and we didn't have to make any kind of modifications to get them to fit the Mustang.

More power, less underhood heat, and looks that will last? Yeah, you could say we are happy with the new Flowmaster headers on our ‘Stang.

We know the added power from the velocity spike and larger primaries, along with the reduced underhood temps from the thick stainless and ceramic coating, will both pay dividends on the Mustang long into the future. Overall, we were pleased with the final product.

The Final Gear…

Flowmaster’s experience in the performance exhaust aftermarket is evident in the Scavenger Series Elite Headers. They aren’t cheaply built headers, but that’s the point. You’re still getting a lot for the money with these headers considering they are coated and stainless steel – along with the power adding features that are usually only found on more expensive headers. 

Our friends over at Kooks Custom Headers are at it again. The 2011-current 5.0L powerplant found in the Mustang has been setting the industry on fire with its performance and power, and after careful examination of the marketplace, the team at Kooks decided that building a true, big-tube header to connect to the factory exhaust was the next step for their product line. Why are these important, you ask? Because as we move forward, it’s expected that Big Brother will continue to exert its influence upon the automotive aftermarket, clamping down on the performance parts that can be manufactured and sold to the buying public in the interest of emissions control.

True big-tube header performance in a small package – these are designed for the weekend warrior who doesn’t want to deal with emissions concerns.

The Super Street Series are a huge improvement over the stock pipes, with large 1 7/8-inch primaries and 3-inch collectors, with 3/8″ flanges for sealing superiority. In addition, the headers are constructed from 304 stainless steel, which provides rust resistance throughout the life of the product. These are designed to be a direct-fit replacement for the factory manifolds, bolt right up to the factory cat pipe, and will provide a proven 10-12 horsepower and corresponding torque gain throughout the powerband. No cutting or welding is required for installation – they bolt right in.

JDM Engineering just tested a set of these on a customer’s car and were impressed with the fit, finish, and dyno performance. JDM’s Jim D’Amore, Jr. explained, “With even a high flow catted mid-pipe, many of the 2011-up cars will still have a hard time passing an OBD-II emissions test even with proper tuning. Kooks now offers a cost effective way around this problem. The Super Street headers allow you to easily change your high flow mid-pipe, used for off road use, for a stock catted mid-pipe for every day street use. With proper tuning, your Mustang will not have issues when it comes to inspection time either.”

JDM Engineering tested the Kooks Super Street Headers on a 2012 Mustang GT. According to D’Amore, “Base line runs (run file 02) were done with a Steeda CAI, GT500 mufflers and JDM Tune. All other powertrain components remained stock. In run file 04, all factors remained unchanged with the addition of the Kooks Super Street Headers. On run file 05 the high flow H-pipe was added.”

Continuing D’Amore said, “Initial testing of these headers showed an increase of 10 rear wheel horsepower and 8 foot pounds of torque at peak, and an average of 14 rear wheel horsepower and 13 foot pounds of torque in the midrange. When combining the Kooks Super Street Headers with a high flow H-Pipe, JDM recorded an increase of 8 more rear wheel horsepower and 10 more foot pounds of torque at peak and even more (10-15) in the midrange power band.”

http://www.youtube.com/watch?v=kgrCSeuvTIY

According to Kooks’ Chris Clark, “This is a new venture for Kooks that we are taking head on.  We have been striving to make emissions-friendly exhaust systems for the last couple of years.  It started with the introduction of our Ultra High Performance 49 State EPA Legal Green Catalytic Converters last year and is growing with the addition of our new “Super Street” series of headers.”

“The idea behind the Super Street series, is to offer a 304 Grade Stainless Steel header that is lightweight, produces horsepower and torque and will enable anyone to pass emissions,” continued Clark. “These OEM connections headers produced an average of 13 RWHP on a dyno and over 10 ft lbs of torque gain.  They weigh 4 pounds less than factory manifolds and up to 8 pounds less than the competitors.  They bolt directly up to stock cats, and we are finishing up our Off-Road X or H pipe that will connect to these headers.” With an expected retail price in the mid-$600 range, these are sure to be a winner.

If you’ve ever built a race car, then you know the amount of extreme heat a high horsepower engine can produce. The under hood temperatures can reach as high as 400 degrees, and with all of the excessive heat, comes the loss of power. A loss of power means slower times at the dragstrip, and that’s something you definitely don’t want from a drag car!

There are many ways to reduce engine heat, but one way in particular is having Jet-Hot Ceramic Coatings prepare your racing headers and exhaust. Having your headers sprayed in Jet-Hot’s ceramic coating not only adds a protective, unique, and beautiful luster to your exhaust, but it also helps repel unnecessary, power-robbing engine heat.

With Project BlownZ making close to 1,500 HP this season, we could definitely benefit from additional cooling properties from our high horsepower powerhouse. We previously brought you the installation story of BlownZ’s Kooks headers and Vibrant exhaust, but we were running them uncoated, and it had an effect on our engine temperatures. We wanted to remedy that problem this season, so we put in a call to the good folks over at Jet-Hot Ceramic Coatings for their Extreme 2500 treatment.

But we’re not going to simply call them, have them coat our pipes, and reinstall the exhaust. Because frankly, there’s no story in that. Instead, we’ve decided to document the Jet-Hot process from start to finish, with plenty of photographs and information to help you get a better understanding of the processes and procedures involved in accomplishing that Jet-Hot coating!

To provide expertise and further insight is Dave Burton, of Jet-Hot’s Research & Development team. Burton will be helping us explain the history, benefits, and what you can expect from Jet-Hot Coatings.

Jet-Hot Coatings, and What They Do…

There are many benefits to having your headers coated by Jet-Hot, and we’re going to share all of them with you in this story. But before we do, we think it’s only best that you give a breif history on their company.

Their beginnings start humble and interesting, when the company founders, former servicemen, had begun coating jet-fighter engine and submarine components that are typically subjected to high temperatures, cyclical stress loads, and corrosive environments.

If Jet-Hot's ceramic coatings suffice in the military's war vehicles like the Stryker, we're pretty sure it's more than adequate for your drag car.

Eventually, Jet-Hot earned a contract to coat the exhaust system on the Stryker combat vehicle, a vehicle that the U.S Army continues to rely on today. But they found their real calling with the performance automotive aftermarket during the 1980′s, and they’ve become one of the go-to sources for the enthusiast’s ceramic coating needs ever since.

If the United States government can rely on them when it comes to their multi-million dollar war equipment, then you know that they can be counted on for your project vehicle.

The Extreme 2500 Coating, and Why We’ve Selected it

So why bother with ceramic coating in the first place? Well the answer for that is a simple one. First, like we’ve mentioned earlier, it helps lower underhood tempretures by keeping heat from radiating/convecting out of the pipes. Secondly, it helps the exhaust flow by keeping the gases hot and energetic as they pass through. Thirdly, and perhaps most importantly depending on your climate, it protects against corrosion from the elements. In BlownZ’s case, corrosion isn’t really an issue with a stainless steel exhaust system, but it is very important to those utilizing mild steel tubing or cast iron manifolds.

Jet-Hot has three different levels of coating, all of which are high-quality and equally impressive. However, each grade has its specific requirements and limitations. The standard coating level is referred as the Extreme 1300 Series, and it’s essentially a form of basic corrosion protection and/or thermal management. The 1300 is perfect for keeping the heat inside of the pipes, while providing a gleaming show car finish.

This is the driver's side header off of BlownZ, prior to having our pipes shipped to Jet-Hot. They'll be removing the debris gathered from all of the 8-second blasts down the track.

If you’re looking for a budget-friendly Jet-Hot coating that can give you the general benefits of corrosion protection and thermal heat management, than this is for you. 

Plus, it can handle all of the heat and corrosive environments of a naturally-aspirated street/strip car. It’s even available in 50 different colors of coating, and Jet-hot can mix and match any color to your liking from their vast inventory of hues.

The next step up in the Jet-Hot line is the Extreme 2000 series, and it’s what Burton refers to as the intermediate level thermal coating, which is applied with thermal spray equipment, and only to the outside of the surface.

As Burton tells us, “It’s able to withstand more heat than the 1300 Series (used on parts over 1,300 degrees), but isn’t quite up to task of holding up to extreme temperatures that are produced from supercharged and turbocharged engines.”

That’s where the Extreme 2500 Series comes in, and while it provides the roughest-looking outward appearance in terms of finish, it’s also the most heat-resistant ceramic coating that you can order from Jet-Hot.

Knowing full well the amount of heat that a supercharged, 388 ci. LSX can produce, we opted for this level of coating for BlownZ.”If you’re running an engine with boost, then we highly recommend the Extreme 2500 Series coating,” said Burton.

The Extreme 2500 Series is so durable in fact, that it can withstand temperatures of up to 4,200 degrees Fahrenheit! This level of coating is fully ceramic, and provides insulative properties that reduce the outside skin-temperatures of the parts.

As soon as Jet-Hot receives your exhaust components, they immediately issue them an identification number. They inscribe them with the number, and take photos for their records.

Applying the Extreme 2500 Coating to BlownZ’s Exhaust

Jet-Hot receives headers and exhaust systems from enthusiasts all over the world, every day! With so many components flooding their facility, they’ve developed a unique process that helps make sure that the customer receives the correct part(s) back, once the process is complete.

What they do is scribe each component with an identification number that ties the part(s) with the customer, the coating that has been requested, and any other special instructions that the customer requires. This is probably a good idea, considering the entire process can take up to three days to complete.

Once received into Jet-Hot's possession, the exhaust components go through the 'pre-blast heat' phase, which cleans all of the oil, grease, and random debris from the parts.

Once the components have been identified, each one is cleaned and freed from all oils and other contaminants (dust, dirt, road tar, traction compound, tire rubber, etc.) to ensure a proper adhesion of the Jet Hot coating. Following which, surface preparation takes place by grit-blasting every inch of the part to remove any oxidation, and also to provide a better anchor pattern for improved adhesion.

Then the parts are blown off with “clean air” to remove any remaining debris and coated to various coatings that Jet-Hot’s customers request. “We make sure to thoroughly clean every part prior to applying the coating, to ensure proper adhesion,” Burton tells us.

Once free of the debris, the parts are cured in an oven to prepare for Jet-Hot’s ceramic coating. Finally, the parts will either get polished or sent back to surface preparation for a topcoat, that according to Burton requires yet another curing process.

Once the pipes are cleaned, they get grit-blasted (top left) and base coated.

To ensure that the right coating has been applied without any defects, the parts are given a final inspection prior to shipping. They are properly packaged to protect the components during transit back to the customer.

As you can see in the photos, that’s exactly what they did with our exhaust. To give our Camaro some individuality, we even had Jet-Hot apply their name and our parent company’s logo onto the header primaries – we think it looks great!

Once the parts are final coated in the selected hue, they are tested for any defects in the coating. The final stage, and obvious one, is shipping. Jet-Hot does a very good job making sure that all of their customers' products get shipped back to them undamaged, and in perfect condition.

Conclusion

Now that we’ve had BlownZ’s header and exhaust system coated, we’re looking forward to seeing how they perform. It will help keep our engine operating temperatures down, while giving BlownZ an additional, personalized touch.

After we had the opportunity to admire our newly coated headers, we promptly installed them back into BlownZ. After all, this is a race car, not a trophy queen!

The best part of the coating is that it can last for up to 20 years, and Jet-Hot provides a lifetime warranty on everything they coat – no questions asked! In a world filled with disposable everything, it’s good to know that some things can hold up to the test of time.

The warranty is even transferable to to future owners for the remainder of the component’s life. So if you ever change your setup, you can sell your exhaust components to someone else, and they can enjoy the benefits of Jet-Hot too! Now that you know everything about Jet-Hot Ceramic Coatings and what they can do you, is there any reason not to step up to the plate for your project car?

As progress continues on our Project BlownZ 2002 Camaro, we’re making it a point to select the best products possible to help us in our build. We wanted to show our readers what’s possible for a x275 drag radial car. We’re continuously tuning, adjusting, and keeping ourselves plenty busy with this awesome dragstrip missile.

Parts We’ll Be Using For this Installment

• Kooks Race Headers (PN 6501-2R-MC)
• Vibrant 4-inch Race Mufflers (PN 17975)
• Vibrant 4-inch Oval Stainless Tubing (PN 131484)
• Vibrant 4-inch Oval To Round Transition (PN 13172)
• Vibrant 4-inch V-Band Clamps (PN 1493)

We don’t want to leave anything on the table, so when it came to our exhaust system we turned to Kooks Custom Headers and Vibrant Performance. Both of these companies construct high-quality, impressively designed exhaust components for optimum performance capabilities.

Since our Camaro is a ‘strip-only machine, we have forgone the use of any kind of catalytic converters and the rest of the OEM-style exhaust system. So you might want to consider this before you mimic this exhaust during your build if your car is still sees regular street usage.

We are also fortunate enough to have Kooks Headers CEO and company founder George “Jr.” Kryssing, and Marketing/PR Coordinator Donavan Griffith from Vibrant Performance on hand to lend their insight and expertise along the way.

Here are the 304 stainless steel Kooks long-tubes spec'ing in with 2-inch primaries and 3.5-inch collectors (PN 6501-2R-MC). You'll also note in this photo the patented scavenger spikes.

Kooks Headers

Kooks has been in business for over fifty years, and is widely used in many applications from street cars to NASCAR. They constantly expanded their markets as the hobby changes, and they even specialize in building one-off headers such as LS-swaps into older muscle cars, and full-on race cars. They make their headers from high-quality 304 stainless and use the latest technology available in the aftermarket to manufacture the best product possible for the racing enthusiast.

The examples we’ll be using for BlownZ (Part# 6501-2R-MC) feature 2-inch primaries that direct the hot exhaust gasses straight into a 3-1/2″ collector for an optimized flow through pattern that limits restriction and maximizes horsepower.

Here's what the scavenger spike looks like once you remove the collector from the end of the header assembly.

The headers are specifically designed for the LS-powered fourth generation F-bodies with the enthusiast in mind. Together, they weigh 35 pounds with all of the included hardware. Depending on your skills, the access to a lift, and your set up, they can typically be installed in around 5 to 6 hours. Kooks recommends that you use their in-house supplied gaskets (Part # 8024) for your install.

We went with the 2-inch primaries and 3.5-inch collectors for the simple fact that these headers will be getting bolted to a 388ci stroked and ProCharged blown Camaro. We wanted as much flow as possible with the 20 psi that BlownZ’ s LSX will be producing. The headers are constructed from an 18-gauge stainless steel and the flange thickness is 3/8-inch.

Vibrant Mufflers, Transition Adapters, and Oval Pipes

Obviously we can’t just run open headers, and for one reason – because they simply aren’t legal at most dragstrips. So we turned to Vibrant Performance. Vibrant is a company known in the aftermarket community for catering to turbocharged and supercharged vehicles from all over the world. Vibrant focuses on fabrication supplies, and helps enthusiasts looking to build their own custom exhaust systems with mufflers, flanges, gaskets, and tubing – making them a great resource for racers.

For BlownZ, we pieced together our own custom kit to complete our exhaust system. We ordered a pair of 4-inch Vibrant race mufflers (Part # 17975), two 4-inch oval stainless straight steel tubing sections (Part # 13184), two oval to round 4-inch OD round transition adapters (Part # 13172), and completed the package with stainless V-band flange assemblies (Part # 1493).

The Vibrant race mufflers offer very little in the form of baffling, in fact, they’re better described as a resonator. It’s a pure race application that’s not legal for street use, but since it’s illegal to not run some form of sound reduction, it’s a must for our purpose-built drag car. It maximizes flow with the patent “True Straight Through” perforated internals that doesn’t sacrifice horsepower or torque.

We’ve selected the 4-inch oval tubing for the all the same reasons, as their design offers the same amount of flow as round tubing, without sacrificing ground clearance. Since the 4th-gens never came equipped with a traditional dual exhaust system from the factory, body to ground clearance becomes an issue with these cars.

Fabricating BlownZ’s Exhaust

Here, shop dawg Sean welds the O2 sensor bung for the F.A.S.T EFI into place on the Kooks headers. Thankfully, we have a full line of Lincoln Electric welding products to complete the job at hand!

This is the fun part: installation. Excited to get our project completed, we promptly removed everything from its packaging and set to work.

Once we had our muffler and header V-band connections welded up, we were finally ready to install the whole system in BlownZ. Installing a set of long-tube headers is typically a challenging and time consuming process in a normal 4th Gen F-body street car; especially one that still has a smog pump, an air conditioning unit, and the factory K-member.

As you can clearly see, it's quite a tight fit on either side of the engine bay. If you look at the photo on the right, you can see how close our steering rack is to our 2-inch primaries. On top each of the primaries, are the bungs that we will be installing our AEM O2 sensors.

However, our installation wasn’t that complex since BlownZ has none of those things. The Spohn Performance K-Member we are using particularly helped with the install. Spohn designed their F-body K-Member specifically for this type of situation, and built in plenty of extra room around the engine block for big headers, and piping for power adders. Combine that with the fact that we have access to a Bendpak lift in our Power Automedia shop, our in-house technicians had them bolted up to our 388 with little trouble within a few hours.

For those of you rocking a stock-style arrangement on your F-body you will need to remove the steering rack, the spark plugs and wires, and more than likely will have to unbolt the motor mounts from the engine block. This allows more room and the ability to move your engine if necessary to ease installation.

In this shot you can see our driver's side header with the Vibrant muffler and the O2 as installed in our Camaro. The tiny muffler then flows into the oval-to-round adapter and then into the 4-inch oval pipe.

When installing headers, it’s always best to use an anti-seize agent on the header bolts prior to installation. This not only prevents the bolts from becoming loose overtime, but it almost guarantees that they don’t become permanently welded into the cylinder head threading due to all of the excess heat. We like to think of it as cheap insurance.

This prefacing to transition makes the life of the exhaust builder much easier, since he doesn’t have to waste valuable time fabricating a piece that will fit, and hoping it won’t leak. Plus, it ensures a restriction-less flow pattern and a clean look.

Once the adapters were fitted into place, we grabbed the oval stainless tubing off of our workbench and attached them to the adapters. This is where our stainless steel V-band clamp from Vibrant would come into play. It promises a gasket-less seal to our adapters, while coming complete with a quick-release locking mechanism that ensures a tight fit and easy removal.

In these four shots, you can see how we welded up our Vibrant pipes to the Kooks headers. After a few passes on the dragstrip we added a pair of mounting brackets to quell the few squeaks and rattles we had.

We asked Donavan about the technology incorporated into the design of these clamps, and he had this to say, “The most innovative part we have in this build, are the V-clamps. Our line of clamps have received the most attention in engineering, as they are installed and uninstalled frequently.”

V-band clamps feature what Donavan referred to as a “male/female” design that works very well, in stressful operating conditions that highly modified drag cars see. They are an effective alternative to the typical flanged or slip-fit connectors.

Conclusion

Our completed exhaust system simply looks awesome under our Camaro, and we're more than happy with the components we've selected. We admit it would be a bit much for a street car, so you may want to consider that if you're looking to mimic this setup.

Our Kooks/Vibrant header and exhaust system is completed, and successfully installed into our BlownZ Camaro. The fit and finish of the headers is superb, and the Vibrant components allowed us to finish out our custom race exhaust without a hitch. If you want to copy this system for your car, you need to keep in mind that is a track-only drag car. This car will never see street duty, and that’s just fine by us. Stay tuned for the next chapter as we continue the saga of BlownZ!

Selecting an exhaust system for your muscle car is probably one of the most important choices you will make. Should it be loud or quiet? Whatever you pick, the sound is what defines the build. But outside the sound, you want the exhaust to look good as well. That’s why when it came to choosing an exhaust system for our Project Swinger Nova, we went with a name synonymous with muscle cars – Flowmaster Mufflers. But we just didn’t stop there, we sent our exhaust system out to Jet-Hot Coatings to help keep temperatures cooler while also sprucing up the looks.

Exhaling Properly

Our Project Swinger is moving along nicely, and we’re down to some of those small details that can easily be overlooked. We can’t wait to get out on the street and enjoy the fruits of all the labor and long hours put into this project..for now however the work continues.

To date we’ve figured out how to get our GM Performance Parts LSA crate engine into the car, fitted the trans, the list goes on and on. Now we need to tackle that unseen detail that contributes both the performance and the excitement of any project car, the exhaust system. We do after all want to make sure that this supercharged beast can exhale as well as it can inhale and sounds good while doing it.

We started with a Flowaster's U-Fit dual exhaust kit along with a set of Super 44 mufflers. After assembly, we sent project Swinger’s entire exhaust system to Jet-Hot for a polished coating.

Some Assembly Required

Obviously when Swinger originally rolled off the assembly line Novas were only factory equipped from the folks at GM with a small block Chevy. I doubt any of the engineers of that day had even fathomed the stellar performance of the LSA engine we’re installing. As such there is no direct “bolt in” exhaust system for our application so we’ll need to make one of our own.

Before it could be coated, we had to build and weld the exhaust using a Flowmaster U-fit kit and mufflers.

We turned to the good people at Flowmaster and got hooked up with one of their U-fit kits in 2 ½” diameter (part number : 15936). This kit also includes the components to construct a balance or “H-pipe” so that exhaust pulses are balanced appropriately. Last giving us that signature muscle car sound is a set of Flowmaster’s Supper 44 mufflers (part #: 942548).

With the engine installed the first task at hand was to start at the front and fit the balance pipe kit, once this was satisfactory it was onto the rest of it. Our mufflers and associated pipers were mocked up, followed by the construction of the over axle setup and tail pipes. Once everything was checked for clearance and fit was satisfactory it was removed for final welding.

Getting the Most Out of Our Investment

Let’s face it, we have a lot of time, hard work and money invested in this project. As such we need to make sure that all of our components not only last long, but take full advantage of technologies that are available to enthusiasts today. So with that mindset we shipped the completed exhaust for project Swinger out to Jet-Hot coatings to get coated from the headers to the exhaust tip.

The Jet-Hot coating on this system  will not only help with heat control under the hood and inside the car, but will also provide corrosion resistance for our exhaust system that will allow it to endure for years to come. Not to mention that the exhaust system will have a great looking appearance that can easily be maintained.

Benefits of Coatings

Performance

• Reduces under-hood temperatures
• Improves thermal efficiency of the engine system
• Helps maintain uniform temperature throughout the exhaust system

Protection

• Can help extend the life of neighboring components
• Improves thermal oxidation protection at higher temperatures
• Provides protection up to 2,500F (Jet-Hot Extreme 2500 series)

Polish

• Provides a clean appearance
• Available in a variety of colors and finishes
• Unlike some chromes, Jet-Hot’s silvery finish won’t blue
• Easy to clean

The Process

When it comes to getting your parts coated, first fill out Jet-Hot’s online ordering form so you can receive a proper quote on your order. For the sake of coating an exhaust system inside and out, here are their prices:

• $355 for a pair of long tube headers
• $30 per linear foot of exhaust piping in 2.5-inch diameter
• $125-$145 per muffler (depending on length)
• Plus return shipping

Upon receiving, cataloging, inspecting and photographing our parts at their Burlington, NC facility the crew at Jet Hot begin the coating process by cleaning the parts. This cleaning removes both organic and inorganic material from the parts. Things as minor as the oils from your skin as well as any other contaminant that you can imagine must be removed prior to coating. To remove these oils on most parts Jet Hot uses an oven and literally bakes the parts at 650 degrees for an hour. Parts that would be damaged by such a process are solvent or alkaline washed instead.

Left: Parts that can tolerate the heat initially are cleaned at 650 degrees in a large oven. Right: A spray gun is used to coat the outside of parts while a proprietary method is used to do the insides.

After the cleaning or washing process has been completed, the exhaust parts are then grit blasted to get the material down to the “white” metal, this process also allows for proper surface conditions for the coating to adhere to. Parts such as our exhaust components are grit blasted both inside and out.

Jet-Hot Coatings Shop Tour

We were lucky enough to go to Jet-Hot’s east coast facility for a complete shop tour on how the coating process works. Check out that article here.

From here parts are sent to the curing stage where both convection and infrared technologies combine to cure the part in an expedited and effective manner. Parts are then burnished with another light grit blasting and sent for a final coat and curing before final inspection and shipment.

Since our complete exhaust system is being polished it has one more step to go through, tumble polishing. After 10-20 minutes in the tumble polisher the parts are removed and cleaned again, then given a final hand polishing.

Jet-Hot's coatings are available in a number of different colors, from traditional blacks and grey's to red, blue, green, and other colors to fit your tastes. To apply these, once the base coat on a part is cured, it's sandblasted using a light grit sandpaper to create a proper adhesion surface. The top layer of coating containing the color is then applied by hand, just as the base coat was.

Controlling the Heat

Supercharged engines will produce a lot of heat over extended usage or under hard use. Heat of course is the enemy of both horsepower and parts. Excessive heat robs you of performance and steals your hard earned money in parts failures.

Left: Beautiful, yet durable the process leaves the stampings readable on our Super 44 Flowmaster Mufflers. Right: You can even read the part number on the backside of the muffler.

While Dan does tell us, “There is no specific value for the temperature reduction that can be attributed, since different parts generate different levels of heat.  This also must be clarified additionally with the type of coating that is applied to the exhaust components under the hood of the vehicle as different coating have different temperature resistance levels.” To that end, by having our system coated at Jet-Hot we expect to see a reduction in exhaust heat under the hood and heat transfer into the car versus an uncoated system.

Aiding the Flow

From here you can see how nicely the Flowmaster U-fit kit works on project Swinger

We all know that better flow equals more horsepower. What many enthusiasts do not realize is the additional benefits of Jet-Hot coatings to parts where flow is critical. Since like everyone else we are trying to wring as much horsepower out of this project as possible, we’ll take every advantage we can get.

The inner coating applied to our exhaust system known as Jet-Hot Flow Coating will allow for a uniform surface across the entire exhaust system. According to Burton, “Laminar flow is improved with the processes that Jet-Hot performs.”

This additional benefit may be even better realized in the case of hand built exhaust systems such as ours where multiple components were welded together. Since we can’t see the inside of those welded joints it stands to reason they could cause unwanted turbulence. Smoothing this out with the uniform surface from the Flow Coating will help keep those spent gasses flowing quickly out Swinger’s pipes.

Finishing Touches

We’ve all experienced or seen shiny parts that lose their luster over time. This is not the case with Jet-Hot products, “Jet-Hot High Performance Coatings are a long term coating, which is why we offer a no questions asked lifetime warranty on our coatings,” explained Burton. “A lot of the life of the part in terms of the coating is a direct relationship with the care that the customer maintains with his parts.  Cleaning and an occasional polish will go a long way to maintaining the look of the parts for many years to come.”

Left: We can't wait to hear this custom system rumble when we fire up swinger and hit the road and track for the first time. Right: It's almost criminal to hide parts that fit and look this good under the car.

With Flowmaster’s U-Weld kit, we were able to easy assemble a high-quality, complete exhaust system for our LSA-powered Nova. On top of that, we had Jet-Hot coat our complete exhaust system so that the bottom of the car will look at good as the top will for years to come, while also providing us with much-needed heat-blocking protection.

For a significant number of Corvette owners, the car as delivered from the factory is as good as it can possibly be – they go to great lengths to preserve originality and maintain their Vette exactly as it was when it sat in the dealer’s showroom. Others take pleasure in customizing their Corvette, extracting more performance wherever possible.

You might guess what category we fall into.

So, as soon as we got Project Y2k in the shop, we rolled it on the dyno to get some baseline numbers, then before the drum on our DynoJet had stopped turning, we had our friends at Corvette Central on the phone. You see, they’ve launched a new performance division, sensibly named Corvette Central Performance, and they’ve got staged upgrade packages lined up for the C5 – a perfect fit!

Per Corvette Central’s Matt Gessler, creating the new performance brand was the next logical step. “As our website demonstrates, there is an impressive array of performance products available for Corvettes,” he explains. “But depending on the combination of parts ultimately selected, performance can either be improved or hampered.  With this in mind, we want to eliminate the guesswork for late model Corvette owners who are searching for increased performance.  The C5 performance packages are a great example of this.  We’ve spent a lot of time researching and developing the product mix on Corvette Central Performance.  As with every other product we sell, we source our performance products with the question ‘Would I install this on my own car?’ in mind.”

In this two-part series, we’ll show you where we started, do stages 1 and 2 with trips back to the dyno between each stage, then head to the dragstrip to get some real-world performance numbers. Follow along as we turn our decade-old project Corvette into a snarling hot rod that will outrun a stock LS3 C6!

The PCM Acid Test


While we were taking care of business with Project Y2k, we decided to do a little bit of preventative maintenance with the battery. C5 and C6 Corvettes have a peculiar design flaw – the battery is perched directly above the PCM, and any spill or leak drips acid directly on the engine’s brain and main control harness. Couple that with the side terminal battery design which can develop cracks and the clock is ticking; it’s not a matter of “if” you’ll damage the PCM, it’s a matter of “when.”

Who thought putting the PCM directly under the battery was a good idea?

To save ourselves future headaches, we sourced ourselves an OPTIMA Red Top AGM (Absorbed Glass Mat) battery, which won’t leak or spill, and is far more durable than a conventional battery. It’s a direct replacement for the stock piece, and as an added bonus, OPTIMA batteries are also far more tolerant to storage, so that when we park our Corvette for a while, it will go “vroom” instead of “click” when we go to start it up again.

Our PCM is intact, and the OPTIMA Red Top will prevent damage from acid leaks or spills.

Baseline Testing: A Factory Freak?

The 2000 Corvette was rated at 345 horsepower “at the brochure,” and based on the generally accepted 15% loss through a manual transmission, with a certain amount of hand-waving we arrived at an expected rear wheel horsepower number of something around 293. That’s consistent with the numbers you’ll find online for a stock C5 M6 – something between 290-315 horsepower at the tires.

So, imagine our surprise when our Dynojet (which has proven to be both accurate and repeatable with the scores of cars we’ve tested here at powerTV) reported 317.79 horsepower and 334 pound feet of torque – very, very healthy for an 11 year old bone stock LS1 with 50,000 miles on the clock.

Click on the graph to view full-sized version...

To confirm our findings, we also took Y2k to the dragstrip and made a few laps – while the engine was healthy, our rusty manual transmission launch technique left much to be desired, and the best we could do with an abused stock clutch was 13.480 at 105.43 – even with street tires and a slow 60 foot, a result that put us at the upper end of what an internet search would say is possible from a stock LS1-powered C5.

With the “before” part handled, it was back to the shop to begin our upgrade process with Stage 1, which consists of breathing upgrades on the front end, and Stage 2, which does the same for the outgoing gasses.

Stage 1: Breathe In…

Corvette Central Performance offers their C5 Stage 1 upgrade in two different versions: Part number 305341, for 2001-2004 LS1 Corvettes, and the version we used, part number 305322, for early 1997-2000 Corvettes. The primary difference is that 2001-up Corvettes came from the factory with an LS6-style intake manifold, so that’s not necessary in the kit for the later cars.

Stage 1 Contents:

• GM Factory LS6 Intake Manifold
• Callaway Honker Cold Air Intake
• Throttle Body Coolant Bypass Kit
• FAST Flash Programmer

Our upgrades began with the removal of the stock LS1 intake manifold. Thankfully, the design of the LS engine makes intake swaps very simple, compared to doing the same thing on a traditional small block Chevy. No water in the intake, and no gaskets to scrape!

While the LS1 and LS6 intake manifolds are pretty much indistinguishable from the top, flip them over and the LS6 is easy to identify by its flat underside, compared to the recessed floor on the LS1. The stock cooling lines won't clear an unmodified LS6 manifold, so Corvette Central provides a rerouting kit to go with the new manifold.

The new manifold is definitely a "stealth" mod for early LS1's, and adds a decent performance increase all by itself.

This is the inside of the stock airbox lid, which draws air from behind an enclosed part of the bumper, through those channels molded into the lid.

Callaway's Honker air intake uses a high-flow reusable oiled cotton gauze filter element, and draws air from the high-pressure area also used to feed the radiator from underneath the nose of the car. It also replaces the stock "air bridge" that connects the intake to the mass airflow sensor.

Installing the Callaway intake does require cutting a hole in the radiator shroud, but the provided template and comprehensive instructions make it an easy task. The base of the air cleaner assembly then gets pop-riveted to the shroud.

The final piece of hardware in Stage 1 is the throttle body coolant bypass, which is a simple barbed fitting that connects the feed and return coolant hoses together to help prevent the throttle body from warming up - Since we're in SoCal, a frozen-shut throttle blade isn't a real possibility. With all the pieces in place, there's just one thing left before we head back to the dyno...

A major part of the Corvette Central Performance Stage 1 kit is the included FAST flash tuner, which we used to reprogram the PCM to take full advantage of the new, less restrictive intake tract. This component will also be important later on down the line as we progress through stages 2-4 and need to tune accordingly.

The Burden of Proof

The installation of Stage 1 was a process well within the capabilities of any moderately handy Corvette owner; not exactly “change the oil” simple, but a good project for someone who might be nervous about modifying their Corvette. Whether you do it yourself or have a shop turn the wrenches, Corvette Central Performance has you covered. Per Gessler, “We have product assistance reps in house for our DIY customers, but we also deal with shops around the world that help Corvette owners who may have more ambition than technical skill.”

With the parts installed, it was time to go back to the Dynojet and see what progress we had made. A few dyno pulls later and we had our result: an average of 337 horsepower and 345 pound feet of torque – an increase of almost exactly 20 HP and 21 torque just from freeing up the intake.

With our Stage 1 mods complete, we had gained 20 horsepower and 21 foot-pounds to the tires.

Stage 2: Breathe Out…

Pleased with what we had accomplished so far, we moved on to Stage 2 – a new axle-back exhaust, plus performance spark plugs and plug wires. Corvette Central Performance offers four different kit options for exhaust – a Borla Stinger system with either round or oval tips, or one of two different Corsa Indy Pace Car systems. We went for the gusto and selected the package with the Corsa system featuring quad 3.5-inch Pro Series stainless steel tips – part number 305418

Stage 2 Contents:

• Borla or Corsa Axle-Back Exhaust
• MSD 8.5mm Conductor Spark Plug Wires
• NGK TR5 Spark Plugs

We're not going to make any outrageous claims about how much horsepower some magic spark plug and plug wire combination will make, but after more than a decade of service, the stock components are plain worn out even if they look OK on the outside. A switch to top quality ignition components will ensure we're getting all the spark we need.

NGK's V-Power plugs have a 45 degree center electrode, which offers improved anti-fouling characteristics. MSD's 8.5mm Super Conductor plug wires are designed for high heat environments, which will be a plus once we get to Stage 3 and install headers.

Corsa's Indy Pace Car exhaust is part of their "sport" series featuring a straight-through muffler design for maximum performance. Their patented RSC technology makes for a free-flowing muffler that doesn't have the interior drone you get with some other designs. If you're looking for a quieter sound, their "touring" designs offer greater sound reduction through a slightly more restrictive layout.

The wrenching on Stage 2 is about as easy as it gets, though removing and replacing those big mufflers is definitely a bit more convenient on a 4-post lift than jackstands...

The new Corsa exhaust goes right back on - it features all-stainless 304 construction, right down to the clamps and hangers, and the mandrel-bent tubing allows a claimed airflow increase of up to 47% better than stock.

With the Stage 2 installation complete, we were back on the Dynojet to quantify our results...

Hooking Up
To maximize the potential we’re extracting from our upgrades to Project Y2k, we turned to Mickey Thompson Tires for a set of sticky Drag Radials. Specifically, we mounted up a pair of P265/40R18 ET Street Radials, which are specifically designed for our Corvette application. M/T has gone to a lot of trouble to make sure they have a drag radial sized appropriately for just about every popular modern performance car, and if your ride will see only limited street use, the ET Street Radial’s DOT rating means you won’t have to buy an extra set of wheels just for the dragstrip.With our new Drag Radials, we won’t have any trouble applying our new-found horsepower to the pavement, and the fact that we’re able to drive them on the street means we won’t be outgunned at the Stoplight Grand Prix either (not that we would do that sort of thing, of course…)

Before we dyno-tested Stage 2, we honestly didn’t know what to expect. Corsa says their exhaust system is good for “up to 10 horsepower,” but the Conventional Internet Wisdom is that until you get to somewhere around 500 rear wheel horsepower, the stock Corvette mufflers aren’t the bottleneck. As far as the spark plug and wire swap went, we had no reason to suspect that we were getting any misfires or power loss with the stock pieces, so we didn’t think any improvement attributable to the ignition would be measurable by the dyno.

With those thoughts in mind, we were definitely pleased when our Stage 2 dyno pulls revealed an average of 340.59 horsepower and 343.00 pound feet of torque. While picking up three horsepower and dropping a couple of pound feet doesn’t sound like anything worth celebrating, it showed that there was a definite benefit to doing the first (and often last) mod most Corvette owners will perform – an axle-back exhaust swap.

Click on the graph to view full-sized version...

There’s no point in making more power if you don’t intend to use it, though, and we did – Just two days after finishing Stage 1 and 2, we were off to our local 1/8th mile dragstrip to see what we’d gained. For reference, our best stock pass (the 13.48 we mentioned earlier) netted us half-track numbers of 8.751 seconds and 80.67 MPH.

With an additional 23 or so horsepower and another nine pound-feet, we knew that Y2k would be quicker, but how much? With the same 2,500 RPM, clutch-saving no-wheelspin launch, our best effort with Stage 1 and 2 complete was an 8.616 at 81.97.

With Stage 1 and 2 installed, we went from 8.751 at 80.67 MPH in the eighth mile stock to a new best of 8.616 at 81.97.

Doing the math, that 8.616 translates to a 13.27 in the quarter mile – a very healthy gain of two tenths of a second. Now, you may be saying (and rightly so) that running the 1320 isn’t the primary mission for a Corvette, but it is a good yardstick for real world performance. Also, it’s a hell of a lot of fun, but that’s beside the point.

Most importantly, since Project Y2k is intended to be a blue collar supercar, competent at just about anything you ask it to do, by installing Corvette Central Performance’s Stage 1 and 2 C5 kits we made a good car even better. The additional power is evident on the street, and uncorking the intake and exhaust had the added side benefit of making the car sound much better too, from idle to redline. It’s a painless performance improvement from a comfort standpoint as well; this car is still a totally comfortable long distance cruiser, with no drone from the exhaust while hammering down the interstate at 70 MPH (where permitted by local laws, of course…)

What’s Next?

As you might logically infer, now that we have the first two stages of our four-part upgrade complete, the next time around we’ll be bringing you Stage 3 and 4, where we add long-tube headers and a mid-pipe, an underdrive crank pulley, then go for the gusto with a new camshaft to really wake up our trusty LS1. Keep an eye out for the next update, where we’ll once again be turning wrenches and spinning rollers with the help of Corvette Central Performance.

When it comes to engine design and tuning, there is a lot more to it than just picking parts and tweaking carbs or fuel maps. Just about every gearhead, from the most experienced engine builder to the average weekend hobbyist knows that headers help you make power, but far too many simply don’t understand the science behind the tubes.

Headers can help you make more power, but they can also bring it down. That twisting, snarling mess of tubing is the last function in a complicated equation that makes an engine work. If you want to get the most out of it, you need the right pipes.

“Most of the modern header technology has come from years of collecting empirical data from trial-and-error experience,” said Todd O’Neil, Exhaust Engineer for Hooker Headers. Over time, these designs have been refined with the aid of computer software. The big header companies have more resources when it comes to designing headers and exhaust components in the virtual world.

This means less cut and weld development, which takes considerably longer. This doesn’t mean that the traditional trial-and-error development is eliminated; it is however compacted, reducing product development time. This speed enhances the market for mass-production designs, but don’t count out the niche manufacturers. While the big boys have bigger budgets, they also tend to focus on the bigger markets, leaving more on the table for the smaller production shops.

Computer modeling has helped push header design beyond the 1980s. By desigining and testing the headers in the virtual world, a lot of time and effort is saved building the actual headers.

How They Work

Headers can provide more than just sending the exhaust to the back. A properly designed header will actually increase the efficiency of the engine, helping to draw more air and fuel into the combustion chamber through a process called scavenging. This process is very similar to a stove pipe or chimney.

Under the right circumstances, the chimney draws air from the room and releases it out the top, this is called drafting. As wind blows across the top of the chimney, a low-pressure area is created inside, drawing air from the room below, which feeds the fire, generating more heat production.

Simple tasks, like welding the a primary tube to the flange can be done using a CNC MIG welder, like this Kooks header.

If the chimney is too small, the effect will be reduced and smoke fills the room. If the chimney is too large, smoke fills the chimney, but the lack of drafting reduces the amount of air feeding the fire.

Engine exhaust works on a similar principle, with mechanical pressure coming from the engine side. As the combustion process ends, the exhaust valve opens, releasing the pressure into the exhaust system.

The air moves from the high pressure chamber to the low pressure exhaust. The rate at which the exhaust gasses move is directly related to the initial pressure inside the header (and exhaust system as a whole).

This is called “blowdown” and is the difference between cylinder pressure and exhaust system pressure. Excessive blowdown pressure means less gas moving into the header on its own, requiring mechanical expulsion (pump action, i.e. piston movement). Reducing blowdown increases the rate of gas movement in the initial stage of the process.

Once past the initial blowdown expulsion, when the pressure between the combustion chamber and exhaust system have equalized, the piston takes over, providing the pump action needed to expel the rest of the exhaust and push it along its way through the exhaust until the piston reaches TDC (top dead center) and the pump action ceases.

The exhaust gasses do not stop when the pump action is finished. The inertia of the hot gasses keeps it moving through the pipe. The exhaust pulse is a not a single action, one blast and it’s over, the repeated pulsing functions like a waveform, just like sound waves. If it were blasted into open space (as in no header or manifold) it would have no positive effect on the engine.

TIG welding each primary tube to the flange is a critical job. A clean weld helps seal the flanges to the head on these headers from Kooks.

Instead, that waveform pulses through the tubing, pushing the gasses in front of it, while pulling the gasses behind it. This creates a vacuum behind each pulse. Overlap between the intake and exhaust lobes of the camshaft means that as the intake valve is opening, the exhaust valve is still open, allowing that newly-created exhaust vacuum to draw fresh air and fuel into the combustion chamber, beyond what is possible through normal atmospheric pressure in the top side of the engine. This process, called scavenging, is one of the biggest benefits of headers over manifolds.

Shorty headers like these Hooker Block Huggers are designed for tight chassis fitment, not optimum flow. While they are substantial step up from stock manifolds, they are just too short to take advantage of tuning and scavenging increases.

The basic principles of exhaust flow are fairly simple; getting the maximum exhaust from point A to point B is where things get interesting. There are many factors at work in the scavenging and blowdown process. Primary tube length and diameter are the main components in the fight for horsepower and torque. From here, we will discuss the mechanics of headers in terms of short, mid-length and long primary tubes.

“Effective header primary tube and component geometry attempts to take advantage of two distinct forces occurring inside the header to increase performance” said O’Neil, “One is the kinetic energy of the gas stream and the resultant low pressure area behind it, and the other is the considerably greater energy of sonic finite amplitude waves that originate upon the opening of the exhaust valve.”

In terms of primary length, amplitude wave tuning is limited to long tube headers. Short and mid-length headers are simply too short to take advantage of the length of the waveform. The most common use for shorty and mid-length headers are cost and clearance.

Hedman has been building headers for over 60 years, so you know they have some incredible OTS (Off The Shelf) designs such as these shortys for a Ford small block.

From The Horse’s Mouth

Dan Lemons; Owner, Lemons Headers

George Kooks Jr.; President, Kooks Custom Headers

Marc Lewis; VP of Marketing, Hedman Performance Group

Todd O’Neil; Exhaust Engineer, Hooker Headers.

These two factors will override the desire for a long-tube header, as those two factors can be deal-breakers. If it doesn’t fit, it doesn’t fit. That doesn’t mean they are useless. Shorty headers are designed to be as effective as possible in terms of getting the flow moving by removing restrictions.

Choosing The Right Tubes

Velocity is the key to the shorty and mid-length header design. The faster the pulse moves through the tubes, the less pressure builds up inside. This is a function of blowdown.

Reducing the blowdown pressure increases the amount of gasses that are expelled without mechanical assistance, which in turn reduces the amount of effort required to pump the remaining gasses out of the chamber. So you would think that a large-tube shorty header would be optimum in this instance, well, not exactly.

“Smaller tubes acts like longer tubes and bigger tubes act like shorter tubes,” says Dan Lemons owner of Lemons Headers. There is a fine line between too big, just right, and too small.

The key is matching the header to the engine, George Kook Jr., president of Kooks Custom Headers told us, “There is such a thing as over scavenging, particularly with merged collectors. This leans out the intake track, resulting in a loss of horsepower.” If it is not sized correctly, a negative loss of mid-range and top end horsepower will be the result.

Complex bends are either made with a CNC bender like this one in the Kooks facility or created from an assortment of smaller sections welded together. Mandrel tubing benders are great for making kink-free bends, but when it comes to headers, a mandrel bent tube has to compromise the bend in order to remove the interior mandrel shaft.

The biggest advantage for shorty headers is the fitment. Short tubes provide the easiest installation of all the tube designs. “The short tube lengths keep the header collector up high and closer to the engine compartment. This reduces the risk of component interference, and ensures the maximum amount of ground clearance for your exhaust. Short tube headers offer respectable power gains over stock exhaust manifolds, but still leave a lot of horsepower and torque inside the combustion chambers, compared to long-tube header designs” says, Marc Lewis, V.P. of Marketing for the Hedman Performance Group.

“Hedman Hedders manufactures the entire gamut of tube length options. With nearly 60 years of design and manufacturing under our belt, Hedman’s selection of short tube header applications that provide maximum ground clearance is unrivaled in the industry.”

Stepped-tube headers offer increased scavenging and flow where a smaller-than-optimum primary tube is required for fit. By stepping up the tube just after the tube makes the first bend, you get the best of both worlds.

For the best performance, a full-length header is better. “Long-tube headers are a design exercise in unsteady gas flow dynamics and attempt to utilize all the potential energy present in the exhaust to evacuate the cylinders,” says O’Neil.

“This means maximizing the kinetic energy effects of short and mid-length headers and combining them with the tremendous tuning advantages of finite amplitude waves.”

The length and diameter of the tubes must match the application. Just because it works on a 1,000 horsepower drag car does not mean it will work on a 400-hp street machine, in fact, it will likely kill a lot of power. Master builders and tuners use this to their advantage.

“We may use a bigger tube to kill some of the engine’s torque to help manage blow to the tire especially if there is nitrous or a blower,” said Dan Lemons. “Nitrous and blower motors like bigger tubes.”

This is where the builder’s experience really comes into play, there is no set formula or rule that dictates the exact design and size of a high-performance header. The biggest drawback for most hobbyists is the fitment. Long-tube headers, at least off-the-shelf units, are designed for a stock chassis. Engine swaps, steering components and other modifications can seriously alter how a header fits.

Coming Together With Collectors

Optimized header collector geometry is the key to tuning the area that holds performance potential for specific applications. In cars with full exhaust systems, the collectors have much less effect than on open collectors systems.

Long tubes don't always work, especially on cars with a substantially lower ride height. That doesn't mean you have to compromise. There are several long-tube header options that are designed to run inside the factory frame, you just have to look.

“Collectors are generally ineffective beyond peak torque, so max HP applications such as drag racing are addressed by ensuring that the outlet diameter is not restrictive at mass flow and that the collector length is appropriate for providing effective reflected wave duration,” said Hooker’s O’Neil.

When you need low RPM torque, such as street and road race applications, a merge style collector provides a tuned choked point that propagates pulse velocity throughout the remainder of the exhaust system, as long as it is properly designed. Merge collectors can sometimes create that over-scavenging effect discussed earlier.

A perfect header would feature a single bend and out to the back of the car. This of course does not work in just about every street car chassis. “Large radius bends, along with keeping the tubing square to the exhaust port without back-cutting the bend at the flange limit constrictions while allowing the header to fit into to the chassis,” Dan Lemons explained.

The collector is a tricky part of the welding process. Each tube must be fully welded to the collector in order to seal the header.

Building Better Build Quality

While they don’t necessarily provide a finite performance boost, what the headers are made of does matter. “Stainless in the same gauge steel is approximately 1.5% heavier due to the dense nickel-chromium content” George Kook Jr. told us.

Stainless has a lower thermal conductivity coefficient, so it helps retain more heat, which helps propagate the exhaust pulse. Stainless steel often doubles the price of a header, but it will also last longer too.

If mild steel is required to meet the budget, adding a ceramic coating to the inside of the header helps. “Heat retention does make horsepower according to the dyno guys,” Dan Lemons said.

“Adding an additional coating on the inside helps control rust and carbon build up inside the tube which would disturb the gas flow. Coating will also help these expensive headers last a long time.”

Gaskets & Hardware

Little tricks like making the header flange a touch larger than the exhaust port to increase scavenging requires the right gaskets. “The collector gaskets we use are SCE copper. Since the copper can’t crush like a fiber gasket we use a thin layer of copper silicone on each side of the port opening.

As for our flange gaskets at the head, again we use the SCE flat annealed copper. Any gasket that is flat will seal at the header flange. I never use the embossed copper type. They’re made for the flange to match the port opening and won’t work with our headers,” said Dan Lemons.

This system from Lemons features large primary headers and an H-pipe to equalize the exhaust pulses between both sides of the engine.

The gasket must match the header opening more than the exhaust port. Any overhang covering the exhaust will cause turbulence, reducing flow and efficiency. Another importance aspect is locking header bolts. Over time, flanges swell and shrink with the heat, particularly with different metals, such as aluminum heads and steel headers. It is also a good idea to re-tighten the bolts after the engine has been warmed up.

There are a few installations tips that you should keep in mind to get the most out of your install. It is highly recommended that you use a flat flange gasket, either the fiber type or an annealed copper gasket. The embossed copper gaskets will fail.

Snaking big primaries along side the engine is a tedious task. The engineers at Lemons Headers are experts.

Lemons Headers suggests using Permatex Ultra Copper high-temp silicone on both sides of the gasket. Heat and differentiating metals are the enemy of threads and bolts, breaking off a header bolt is a massive pain. Fixing a broken header bolt requires removing the head from the engine or the engine from car in most cases.

You can avoid that by applying a generous amount of anti-seize to each header flange bolt. You can also use it with slip-on collectors. Sometime you run into an interference point with the header tubes.

It is OK to add a slight dimple in the tube, that won’t affect the flow any appreciable amount. However, if you need to really knock a section flat, you either need to move the offending component on the chassis or alter the headers. so that they clear without flattening the tubing.

There are many options when it comes to headers, finding the right one requires a little research on your application. Whether your engine makes 400 horsepower or 4,000, there is a header that will get the most out of it, and many others that won’t.

The engine bay in our 2000 F-body Camaro is a tight fit for the massive World Products 454 Warhawk, which should surprise no one considering the stock engine that we removed was an economy grocery getter GM stock V6. For our purpose built drag car, performance is critical, but trying to get our 454 cubic inch monster, with all the high performance trappings and the required massive header tubes, into the stock engine bay where the 232 cubic inch V6 previously lived, was going to take some ingenuity and skill. Enter Lemons Headers.

Dan Lemons hand builds each set of headers for maximum performance in tight spaces. Our F-body Camaro has limited room in the engine bay but Dan custom-made a set of headers that provided plenty of clearance around the oil pan, starter and steering linkage while keeping the primary tubes equal length for performance.

Our previous updates on this 4th Gen Camaro have detailed the specifics on the World Products 454 Warhawk powerplant in the update entitled “454 Warhawk: The Powerhouse,” and the tight space under the hood after mounting the massive engine and ATF Powerglide in the project car update entitled Mounting the World 454 and ATF ‘Glide.” It doesn’t take too much imagination to understand that space in the engine bay was at a premium.

Unwilling to sacrifice power for space saving off the shelf headers, we contacted Dan Lemons of Lemons Headers to craft a set of custom made headers for the beast. The car was hauled up to the Lemons’ facility where the master craftsman fabricated a hand built set of racing headers. In return, Lemons used the freshly built headers as a template for customers with the same engine/chassis combination desiring racing headers. Lemons doesn’t keep any headers in stock – each set is made to order, many from templates like this one.

About Lemons Headers

Dan Lemons started out by building headers for a major header manufacturer in the late 60’s and early 70’s before seeking his fame and fortune as a cabinet maker in Paso Robles, Califonia.  It wasn’t long before the local guys that knew of Lemons previous header work drew the cabinet maker back into making headers.  Once the passion for making custom headers was rekindled, Lemons began making headers for anyone wanting a custom set.

One of his early customers, a Georgian that was very pleased and excited about Dan’s work,  convinced Lemons that he could do this full time. With no business plan, boardroom or list of company officers, Lemons set off to make custom headers under the name Lemons Headers in 1997. “We started by building drag race headers where there were two big demands, spark plug room and ground clearance,” said Lemons. Most of our new drag racing designs have the primary tubes higher than the bottom of the oil pan, so if your wheelstand bottomed out your suspension, it got to your oil pan before the headers.”

Our custom made Lemons Headers offer plenty of access to the spark plugs and clearance for the starter.

Exhaust Theory

Years of experience has proven that exhaust headers improved engine performance significantly by allowing the exhaust to be efficiently moved out of the combustion chamber. That is, when space permits, a long tube with minimal bends for each cylinder to reduce back pressure.  More often that not, the engine bay does not allow for this ideal exhaust configuration. Fenders, firewalls and necessary components like the steering linkage cut down on the space available for header tubes.

When this unavoidable situation happens as a result of replacing a small engine with a much larger high performance motor or when the engine combination you are using doesn’t have an off the shelf set of headers available, the optimal solution is a set of custom built headers.  “Building a set of performance headers requires putting a big tube into a small chassis and trying to get them as close to the same length as possible. This is not an easy task,” says Lemons.

For our project car, Lemons opted to use 18 gauge mild steel stepped from 2″ diameter out of the block to 2 1/8″ at the slip on collector. According to Lemons, “For the weight of the car, stall speed of the convertor, horsepower and cubic inch size of the motor, this design will put the torque and power bands where you want them. Our collectors are fitted with Lemon’s transition cone that helps with the scavenging of exhaust gases from the cylinders.” Lemons says, “this is our typical race collector.”

There was a concern that because of the space limitations, the headers would not be able to removed or installed without raising the engine off of the mounts. “What we did was split the header flange into pairs, meaning two primary tubes on each flange, so that the headers could be removed or installed without lifting the engine.” Even with the tight space, only the steering shaft has to be disconnected to remove the driver’s side headers. “Being able to remove the headers without lifting the engine will make a huge difference at the track if you have to take the headers off for any reason,” added Lemons.

Designing Headers

Dan has a couple of principles that he tries to keep in his header design; large radius bends and keeping the primary tubes as close to the same length as possible. Lemons says these principles help keep the headers flowing freely. Another goal that Lemons always stays true to is building each header by hand so that he is free to bend the tubes in order to fit into the chassis and over the frame.

Even hand building each header does not mean that it is an easy project.  According to Lemons, “The most problematic ones would be the late model Camaro. Everything is very restrictive, especially on the passenger side.” The limited space on the late model F-body chassis is more of challenge and with our specific engine combination, Lemons required us to bring the car in for a custom fitting. For the most part, Lemons says he can make a header system for just about any car; “Ninty-nine percent of the time everything is trouble free and works like it is supposed to.”

From start to finish, it takes Dan and his crew about two days to complete a set of custom headers. Understanding racers, Lemons is even willing to work on weekends if you need your headers quicker than normal.  There is an extra charge for a rush job, but Lemons tries to make sure that his customers are taken care of.

In a perfect world headers would only have one bend, out from the engine and back. With modern chassis and component designs, multiple bends are required. Lemons works to get the largest radius bends that provide ground clearance and performance.

Choosing the Right Headers

With so many different factors to consider when choosing headers, the selection process can be terrifying. To take away some of the fear, Lemons offered this advice, “If you have a stock or mild engine and chassis build, an off-the-shelf header is probably the right way to go.” If you have a wild combination and are looking for every advantage, custom headers are the optimal choice.

Custom Header Options:

• Flange design – one-piece or split
• Primary tube diameter – stepped or single-diameter
• Primary tube length
• Collector diameter
• Collector length
• Stainless or mild steel
• Coated or uncoated

Choice in custom headers for cars bound for the drag strip comes down to a couple important factors; lengths, diameters and bends. Lemons explained, “In a perfect free flowing exhaust world, there would only be one bend in the exhaust system.  Flow would go straight out from the engine and then directed 90 degrees to the back of the car.” Engine bay and chassis design makes that an impossibility in just about every case. Lemons compromises by “trying to keep our designs as free-flowing as possible by using as large a radius in the bends as possible while keeping the primary tube square to the exhaust port without back-cutting the bend at the flange.”

One advantage of custom headers is having the most clearance possible for engine and drivetrain components.

Improving a Tried-and-True Product

Even with a tried and true product, Lemons is always looking to improve. “We put a lot of effort into improving and redesigning our headers. If we feel we can pick up a little more ground clearance, increase space around the starter and oil pan, or improve access to the spark plugs, then we’ll redesign a header.”

The primary tube length can have a big effect on power curve, but when limited space does not permit longer primaries, Lemons uses different diameters of tubing to compensate for length. “The ability to use different tube sizes allows much greater flexibility in designing a header. Smaller diameter tubes act like longer tubes and bigger diameter tubes act like shorter tubes,” said Lemons. As far as stepped headers, Lemons says that a stepped header scavenges better than a straight-tube header and broadens the torque curve. Getting more exhaust gasses out of the combustion chamber means you can put more ignitable fuel in. And we all know what that means: More power!

Lemons takes several other factors into consideration when building a custom set of headers, “Cubic inches of your engine, your compression ratio, how much horsepower you intend to make, the size and weight of the car and tire size, should also be considered,” adds Lemons.

Other information about the vehicle can play into designing a great set of custom headers. If you plan on running mufflers, X-pipes or H-pipes, exhaust flow is affected. According to Lemons, “If a car utilizes a full exhaust system, we may lean toward a larger tube or collector size because of the added back pressure.”  Even the type of torque converter can have a dramatic effect on the header design. A higher stall converter requires more power to spin up while “converters with lower stall speeds will require more torque and smaller tubes. Nitrous and blower motors tend to like bigger tube sizes,” advised Lemons.

Gaskets

Header leaks can be irritating and could risk burning a valve so it’s an issue that Lemons takes seriously. ”We have had great success with copper gaskets, since they’re extremely flat, which promotes an excellent seal, and do not expand or contract as much as fiber gaskets.” The properties that make copper gaskets successful also provide its only drawback. According to Lemons, “Copper can’t crush like a fiber gasket, so we recommend using a thin layer of copper silicone on each side of the port opening.”

Because copper doesn’t expand and contract like fiber gaskets, there is an added benefit of your header bolts not backing out.  ”The combination of heavy-duty header flanges and flat copper gaskets that don’t expand and contract like thin flanges and fiber gaskets, virtually eliminates the potential for bolts to loosen over time,” states Lemons.

Header Material

“We build headers in mild steel and stainless steel with the most significant difference between the two is that stainless costs about twice as much,” Lemons says. “Stainless is a stronger material and won’t rust, but it discolors and weighs more. Mild-steel headers that are well-coated inside and out make a lot of sense, because they’re cheaper, lighter, and very durable.” Regardless of the type of material selected, Lemons says they use 3/8″ thick header and collector flanges with 18 gauge tubing and 16 gauge collectors that are all TIG welded.

Ease of Installation

While designing a set of headers that is simple to install is important, “we won’t sacrifice performance or fitment to make a header easier to install,” Lemons assured us. As the master header builder explained earlier, getting a good fit with good spark plug access and plenty of ground clearance with room around the oil pan and starter is most important. With the options of individual tubes and slip on collectors, even the most complicated set of headers can be installed relatively easily.  ”Many of these headers can be installed in 15 minutes with the engine and starter in place,” says Lemons.

Header Installation Tips From Dan Lemons:

• Header flange gaskets: With all Lemons headers, Lemons recommends using a flat gasket, either a fiber type or an annealed copper gasket. Do not use an embossed copper gasket that has a raised rib around the port. If an SCE flat annealed copper gasket was sent with your order, Lemons recommends applying a thin layer of Permatex Ultra Copper high temp silicone on both sides of the gasket port opening.

• High temp anti-seize: Lemons recommends Permatex Copper Anti-seize to be used on header bolts and slip on collector mounting bolts. For header with Lemons slip on collectors, use a generous amount inside the slip on tubes. This will stop corrosion and help the collector to slip on much easier.

• Individual header tubes: If your header was built as a race style with individual tubes and slip on collectors, the headers will be installed one tube at a time. As you install each tube just snug the header bolts evenly, do not tighten. With all tubes installed, slip the collector on and tighten the mounting bolts. Then go back and tighten the header bolts. Always check around header tubes for brake line, wiring and fuel line clearance.

• Slip on collectors: If your race header has been ceramic coated, there may be overspray inside the slip on tubes at the front of the collector. This should be smoothed off either by hand sanding with 80 grit sand paper or by using a 40 grit flapper wheel on a die grinder or high speed drill motor. Sand just enough to take the roughness off. When installing slip on collectors, coated or not, always apply a generous amount of high temp anti-seize to the inside of the slip on tubes. Cover the entire area inside of the slip on tubes. This will keep the connection from corroding and help the collector to slip on much easier. Lemons slip-on collectors are held on by tabs and bolts. One tab on each collector will be stamped left or right that tab needs to match up with the stamped tab on the header tube.

• Ceramic coated headers: When installing polished silver ceramic coated headers, they should first be wiped down with rubbing alcohol. Use a clean white cloth to apply the alcohol, then a clean dry white cloth to remove the residue. After the headers have been installed, repeat the alcohol cleaning process to any areas that are accessible. This will remove the fingerprints, grease, excess anti-seize, smudges, etc. Start the engine and let it idle for about 5 minutes, then shut the engine off and let it completely cool down. Next run the engine again for about 10 minutes and then let it cool down. This process will help to bake the new finish on, making it tougher and will greatly reduce the chance of any dulling of the finish in the future.

• Spark plug wiring: For Big Block and LS headers Lemons recommends a 45 degree wiring boot and for the Small Block headers Lemons recommends a 90 degree wiring boot.

In a perfect world, most people would prefer a nice pair of ceramic-coated long tubes over shorty headers. They make more power but can pose problems on a street car. They can be hard to install, and in some cases require significant changes to the exhaust system. While coatings add expense, they also promise longer header life and lower temperatures under the hood. Since we had a chance to swap out a set of shorty Hooker headers on our Project “No Bucks” Camaro in favor of Hooker’s new Darkside ceramic coated long tube headers, we thought it would be a good opportunity to see if our preconceived ideas about long tubes and coatings were correct or not. Read along as we will show you the difference in installation as well as on the dyno.

Project “No Bucks” Camaro

Dirty. Red. Neglected. Those three words best describe what we saw when we found this 1991 RS Camaro. The paint showed the car had spent the last 17 years in a driveway instead of a garage, but the body was in great shape with hardly a scratch or dent, and as you might guess from the nickname, the price was right, So far, we have installed a complete MSD ignition, Hooker shorties, a Hooker cat-back, and a NOS nitrous kit. Thirsting for more power on a budget, we decided to make the switch to long tubes.

Shorties Versus Long Tubes

We had previously installed a set of Hooker 1-5/8″ shorty headers on our Camaro. While a header isn’t always the most enjoyable part to put on, shorties allow for a relatively painless install, at least in terms of modifications you have to make to the vehicle. Shorties are generally designed to mate up with the remaining stock exhaust system to give them an OEM-type fitment. And while speaking of OEM, long tubes eliminate the factory catalytic converters, voiding warranties (not an issue on our Camaro, of course) and not allowing you to pass smog (which is a big issue here in California). Because a lot of shorties are designed with stock emissions plumbing and don’t eliminate or relocate the factory cats, it’s still possible to get them certified as 50-state legal. Not so with long tube headers.

The downfall of the shorty headers is inherent in its design. The short runner configuration can cause turbulence in the collector thanks to the proximity of the exhaust ports, while long tubes channel the exhaust gases independently and progressively to a collector under the bottom of the car for a smoother transition. Long tube headers also make it possible to optimize primary tube length for proper exhaust scavenging in a realistic RPM range, which is something that no shorty can accomplish. In our particular case, the fact that we were going to upgrade to 1-3/4” primaries will help with flow as well.

Hooker’s Darkside Long Tube Headers

265-400 Chevy 82-92 Camaro – Part #: 2460-3HKR

• 1 3/4” Primaries
• 3” Collector
• Removable passenger primary for dip stick tube installation
• Works with angle plug heads (short plugs required)
• Coating resists up to 1700 degrees Fahrenheit

The concept behind a header coating is pretty simple – it reduces the amount of heat in your engine bay and also prevents the header from rusting. Typical uncoated mild steel headers will generally have a shorter lifespan due to exposure to the elements, and even condensation on the inside of the tubes. Previously, Hooker had only offered the familiar silver ceramic coating style, but now they have designed a coating that gives people the option of a more ‘stealth’ look. More importantly, it resists heat to a higher temperature.

Swapping the uncoated shorties for Hooker Darkside Long Tubes

Since we were already working with shorties and not the stock exhaust manifolds, our day was a little easier. We were also doing a K-member swap to a tubular version from Spohn at the same time, and killed two birds with one stone. Though removing the K-member does make a header swap easier, it’s not necessary, though you will need to remove the engine mount bolts and jack the engine up some from the bottom to gain clearance

After pulling the negative cable from the battery, the first task was to label all the spark plug wires with their respective cylinders, remove them, and then all the spark plugs as well. Next, we got underneath the Camaro and removed the three collector bolts off each engine bank. Lastly we removed the clamp that holds the Y-pipe to the exhaust.

Removing the bolts on the shorties or the stock manifolds is pretty simple, until you start heading towards that back of the motor where things get a bit tight. We alternated between a 1/4” socket and a standard wrench to get all the bolts off. The driver’s side header will come out from the top

The passenger side needs to be taken out from the bottom after you remove the dip stick tube. This was made easier since we had the crossmember out. Make sure you follow the standard advice to disconnect the battery before you get started because the last thing you want to do is rub the header against the battery terminal on the starter while it is being removed.

Before installing the passenger side header, remove the stock knock sensor that is right in front of the starter. It will be crushed by the header if you don’t remove it (don’t ask how we know). There is a spot on the block on the driver’s side that you can thread it into instead, though you will need to extend the wire to the other side. The passenger side header will go in from the bottom and features a removable fourth runner to ease the installation around the dip stick tube. We utilized the new header gaskets and bolts that Hooker included with the kit.

The driver’s side header slips right into place as well from the bottom, using the new header gaskets and bolts to secure it in place. Before you start wrenching down the bolts, make sure you get all of them in finger tight first, to assure proper alignment of the header onto the mounting surface. Due to the design of the primaries’ short turn, you will need to use the short “peanut”-style spark plugs if you have angle plug heads – standard length plugs won’t even thread in place.

With the new headers in place, we feather-footed the Camaro over to the local exhaust shop with open pipes, where we tasked them with making a Y-pipe better than the dreadful stock design and plumbing our long tubes to the existing cat-back system. If you’ve ever taken a look under one of these cars, you’ll agree that just ditching the crazy stock Y-pipe layout has to be good for a few horsepower all by itself.

Proving the Point

With the new headers and exhaust in place, we noticed that the Camaro sounded a bit more aggressive, and the seat-of-the-pants acceleration was a night-and-day difference. To see how much power we actually picked up, we strapped the Camaro down to our Dynojet and had a run at it. This little 305 picked up an amazing 26 horsepower and 48 ft/lb of torque to the rear wheels! Our “before” horsepower reading of 172 HP and 238 ft/lb of torque gave way to 198 HP and 286 ft/lb of torque – all through a simple header change.

Lowering underhood heat and making more power should be on anyone’s agenda. With the new Darkside coating, these headers can withstand temperatures of up to 1700 degrees, and the insulating effect helps keep heat down and exhaust velocity up. While shorties are great for those that are emissions-minded, the long tubes have once again proven their worth in waking up our Camaro’s V8.

If you’re like most automotive enthusiasts, the modification of your high performance street or strip vehicle begins with the removal of the stock exhaust to make way for a deeper-sounding, more powerful aftermarket exhaust system. And Flowmaster Mufflers, a name is which is synonymous with high performance exhaust and whose products emit a truly unmistakable tone, is quite commonly the go-to source to satisfy your high-horsepower needs.

http://www.youtube.com/watch?v=ckgCrdd1twA

With humble beginnings in 1983, founder Ray Flugger created Flowmaster’s first patented design of a silencer for race cars in an 800 square foot barn in Kenwood, California. What began as a mission to quiet race cars without a loss of horsepower evolved into designs and products able to not only quiet the vehicles, but increase horsepower and fuel economy and provide a great new sound as well. “Between all of those benefits, there are few products that you can put on your car that do all of those things in one easy bolt-on install,” says Flowmaster VP of Marketing Cam Benty.

One of the easiest horsepower upgrades you can do to your car is to take off the stock exhaust and open it up with aftermarket headers and a full exhaust system. On our pet Fox Body Mustang, more commonly known as “Project 666”, we did just that. Because of the fact that Foxes are possibly the most popular performance cars ever built, there’s an almost limitless variety of exhaust parts and complete systems available straight off the shelf for any combination of chassis, transmission, and engine. Even if you’ve gone insane and built a small-block Chevy powered convertible Fox with a Powerglide, chances are that somebody out there makes headers and pipes that will work. By comparison, our Windsor-powered notch is positively mainstream, so our priorities were quality, performance, and ease of installation.

To find those attributes, we looked no further than Kooks Custom Headers and Flowmaster exhaust. Kooks is best known for their amazing stainless headers, with some of the best quality and fit in the industry. Flowmaster needs no introduction, being synonymous with performance mufflers – they hooked us up with their Delta Force System that sounds as good as it flows. Both of these kits came with everything we needed to easily mount them to our Fox Body Mustang.

“Project 666” has a 550hp 408ci engine that runs on pump gas and is fully street legal. The carbureted 351W-based powerplant sports Edelbrock’s Victor Jr. heads, an assembled short block from Ford Performance Solutions, and Harland Sharp rockers.

The specific Kooks headers we selected were their 2” Custom Headers. These headers came with an adapter plate to fit onto our Edelbrock Victor Jr. heads. Because these long-tube headers put their collector flanges farther back under the car than the stock manifolds, we knew that we’d have to do some minor modifications to mate them up to the Flowmaster X-pipe in the kit we’d selected, but a few minutes with a tape measure showed that by leaving the downtubes off the front of the X-pipe and splicing in a pair of 3-bolt flanges, we’d be all set.

Though we have the luxury of a 4-post lift in our shop, thousands of gearheads have done swaps just like this in their driveways using nothing more than a good set of jackstands.

Kooks Stainless Steel Headers for Victor Jr. Heads #5012

When designing the headers, there are a lot of factors to consider. Besides the obvious stuff like primary tube length and layout or allowing for spark plug access and steering shaft clearance, the head and block combination has to be accounted for as well. “When the deck-to-block height fluctuates, so does the position of the headers,” George Rumore from Kooks Custom Headers explains. Also, the cylinder head plays a major role because the exhaust ports on the cylinder head need to match those of the headers, and tubing size needs to be appropriate for the flow capabilities of the heads. “We offer tube sizes from 1 3/4″ to 2″ primaries for the Victor Jr. heads,” added Rumore. Kooks Custom Headers design their headers around these factors, and they manufacture them from 304 stainless steel, chosen for its durability and strength.

Kooks headers feature:

• Stainless 304 Construction
• Wide range of applications for different engine combinations
• Designed specifically for the 9.5 deck with Victor Jr. heads
• Available in 1.75″ and 2” primaries for this application
• 3” stainless merge collector

Flowmaster Delta Flow Header-Back Exhaust #17389

The exhaust we used on our Fox Body Mustang upgrade was the Flowmaster Delta Force System. This kit is intended as an ‘off-road only’ race system designed to mate directly to stock manifolds or “shorty” headers with ball flanges in the same position as the stock exhaust outlets. As we mentioned before, we had to modify the system a bit to mate with our Kooks long tube headers, but because the Flowmaster exhaust is designed to use the stock hanger mounting points, everything else fit perfectly, just as intended. The kit comes with all necessary hardware, eliminating extra trips to the auto parts store. The Flowmaster system includes over-axle plumbing and polished dual rear-exit tips, but since we knew our Moser 9-inch rearend housing would make clearances tight, we decided to forgo running the exhaust all the way to the rear of the car and went with turndowns right after the mufflers. In addition to solving the clearance problem, the dumped exhaust is also a few precious pounds lighter than full tailpipes.

There's plenty of clearance under our Fox for the big 3-inch diameter Flowmaster mufflers, which will quiet down our 408's bark without choking flow.

Instead of a standard H-pipe or X-pipe, this kit comes with the Scavenger X-pipe. This patented design uses a parallel tubing section with a “D” port between sides, giving improved flow and a deeper sound than the standard H-pipe. “When paired up with different parts, like the ones offered in the Delta Force Kit, you definitely will make more power over the H-pipe,” Dale Dotson from Flowmaster explains.

Our Flowmaster exhaust system uses dual Super 40 Series 2-chamber mufflers, with 3" inlets and outlets.

The mufflers that are used in this application are the Super 40 series race mufflers. These mufflers are the best of both worlds. They provide the deep, powerful sound of the standard original 40 series but with the performance and low interior resonance offered by Flowmaster’s Delta Flow Technology. “The upside to the Super 40 over the Standard 40 series is the bigger muffler that handles more power and produces a deeper sound,” Dotson explains. The Super 40 mufflers were developed from the company’s race muffler lineup and feature a black oversized case that keeps the resonance down on the inside of the cab without restricting flow.

Flowmaster Delta Force Kit Benefits

• Deep aggressive tone
• Bolt-n-go system for stock manifolds or shorty headers
• Super 40 Series mufflers
• Scavenger X-pipe

Installation of the Kooks Long Tubes

Installing these headers on “Project 666” was a breeze. Other than clocking the starter to make clearance for the headers, they went on very easily. The supplied adapter plates bolt to the head first, using countersunk hex-head bolts, then the headers bolt to the plates. One tip when installing any kind of stainless or ceramic-coated headers – after they’re bolted up, wipe them down well with a grease-cutting solvent and let them dry before firing the car up for the first time, or your dirty fingerprints will permanently discolor the finish.

The Kooks headers come with adapter plates to convert from the stock in-line bolt pattern to a diagonal 2 3/4" pattern.

To install the adapter plate, first insert the first and last hex head bolts before inserting and tightening down the middle bolts.

After the adapter plate is on, carefully start mounting the headers by bolting them to the adapter plate.

Installing the Flowmaster Header-Back

To mate the Flowmaster Scavenger X-pipe to our long-tube headers, all we had to do was mount three-bolt flanges to the front instead of the supplied downpipes to match up with the collector flanges.

After the Kooks Custom Headers were mounted, we attached the collector on the end with the supplied bolts. After that was done it was time to attach our Flowmaster exhaust.

To span the gap between the collectors and the Scavenger X-pipe, we spliced in a pair of 3-bolt flanges.

Once the flanges were bolted together, we positioned the X-pipe using the supplied hangers and the factory mounting points. Flowmaster provides clamps to secure the pieces of their exhaust system together, but recommends welding the joints if possible, once everything is installed and adjusted properly.

Next, it was time to hang the Super 40 mufflers. We installed the ring clamps to the end of the Scavenger X-pipe and then slipped on the mufflers. Because we wanted to be able to adjust the mufflers to fine tune their position, we chose not to tighten the clamps all the way down yet.

After we installed the hangers on the rear of the mufflers, we were able to get the exhaust positioned, then tightened all the hangers, clamps, and bolts. All there was left to do was install the turndown tips.

In Order to Form a More Perfect Union…

We couldn’t have chosen a better pairing for Project 666 – The Kooks long-tube headers and Flowmaster exhaust are perfectly suited to the deep-breathing needs of our 408, and fit like a custom-built system though they’re both off-the-shelf part numbers. Installation really couldn’t have been much easier, and the sound is awesome, without being so loud that we’ll run afoul of our local drag strip’s noise police.

Mocking up the Drive Train

The first step in this mock up process was to take the Monster crate engine and bolt a brand spankin’ new TCI Pro-X Powerglide Transmission to it. A long time ago, the Powerglide transmission had a reputation as being a little weak in the knees for real power applications, but that was – a long time ago. TCI has perfected taking a stock power glide and making it durable enough to handle just about anything that you can throw at it, but this isn’t a stock glide. This is a TCI Pro-X, and it uses an upgraded case to handle up to 2,000 HP.

Once the big block and the glide were together, we lifted the assembly into Grandma’s engine bay with the Cornwell engine hoist and load leveler. We have to give the Cornwell Tools big props on the load leveler. Attempting to put the engine/transmission combo into the engine bay while the car is on a two post lift is no easy challange, even with the fenders and grill removed. The load leveler simplified what would have been a difficult, and somewhat dangerous task. Finally, we added the Lemons 2-1/4 inch header tubes so that Mike could fab up the steering system ensuring that there was plenty of clearance.

Lemon’s Headers – A Work of Art

The Lemons headers we ordered are a pretty special set up for g-body chassis like Grandma. Lemon’s is one of the only exhaust header companies that specializes in race-type (read: seriously BIG tube) headers for Muscle Car big block applications in early cars.

With our Lemon’s headers, each bank has four 2-1/8-inch headers that step into 2-1/4 inch stainless tubes, which merge into a 4 inch collector. On each side, two of the header tubes route outside the frame and the other two run along the inside of the frame. These headers are designed for the engine mounted in the stock location, but will not fit with with clutch linkage or column shifter linkage.

We are using the TRZ/Flaming river steering rack, so we had already planned on moving the steering column for clearance. We also planned on rerouting the master brake cylinder lines for clearance too. While we were mocking the drivetrain out, we made note that the transmission cross member would have to be fabricated to allow for the massive 4 inch collector.

Transmission Cross Member – Making a 25.5 Legal X-Member

For the 25.5 SFI spec, we needed to build our Transmission cross member within certain parameters. Mike’s next step was fabricating the transmission cross member. Starting by bolting on the Energy Suspension Transmission mount to the tail shaft extension of the transmission, we were able to locate the mounting position of the cross member.

Mike set about fabricating the cross member and transmission mount by measuring and custom fitting pieces of plate steel together, joined by tack welding the metal. This would form the trans mount that would attach to the mild steel cross-member.

Once the cross member pieces were custom fit, tack welded and double checked for fitment, Mike TIG-welded the entire assembly. While we were already under the car, we needed to add a couple more tubes for support and safety. The tranny mount and bar ran perpendicular to the “stringer” tubes, or the floor bars, which go from the rear end mount cradle forward to the frame near the front wheel well area.

These bars are required for 25.5, and provide extra crash protection and frame support. It is cheap insurance and makes the chassis strong as a tank without weighing like one.

With the engine mounted and the transmission mounted in place, test fitting the steering assembly could begin. Steering is extremely important, even in a straight line car, so making sure that the rack placement and steering shafts had good clearance and proper geometry was essential at this stage. The steering shafts would have to be rerouted because of the larger engine and the manual rack and pinion upgrade. Yet again, Mike would have to custom fabricate the entire steering column and rack mounting. We are going to do a more detailed article on this in the future with some more photos, but for now – you can follow along.

TRZ/Flaming River – Manual Steering Rack Conversion

Mounting the steering rack started with removing a mounting pad from the engine cross member. This little mounting boss serves no purpose in this particular chassis, so cutting it off was of no consequence. With the mounting boss removed, the manual steering rack was bolted to the spindle steering arms so that proper rack placement could be determined. The TRZ steering assembly came with two mounting brackets that need to be welded in to place in order to mount the steering rack.

It took a little patience to grind and massage the steering brackets so that they would form a close “air tight” fit to the crossmember. Getting this tight fit is key to a good TIG weld. Keeping in mind that it is easier to take off metal than to add it, Mike made several trips to the grinder, taking off a little bit at a time then test fitting the mount to the frame until it was perfect.

Massaging the mounting brackets until they made an “air tight” fit

There are two brackets that need to be welded to the frame that support the steering rack, and each bracket needs to be custom fit for the best results. Mike made several trips to the grinder and back to the chassis to test fit his work. The quality of the welds and the mounting of the steering rack depended on this level of attention to detail. We recommend strongly that you do not take a short cut here.

Taking no short cuts, these mounting brackets were fitted perfectly to the crossmember.

Now that the rack was firmly mounted to the crossmember, we could focus on routing the steering shafts. With the big engine in place with the Lemons headers attached, there was little room for the steering shaft to run. A new route from the steering rack to the steering column had to be made. Armed with a bi-metal hole saw, we created a new path for the steering shaft by cutting through the cross member.

Making a hole in the crossmember to run the steering shaft

Working from the steering rack back to the steering wheel, we managed to find a decent path through the engine cross member, outside the first two header pipes near the upper A-Arm and through the firewall. Our goal was to route the steering column through the original location in the firewall. This required manufacturing a new mounting plate for the steering column to run through. Again, patience was key to fabricating a plate that covered the existing firewall hole and allowed the steering shaft to run through it.

Our new firewall steering column plate

All the pieces were in place for us to run the steering shaft from the wheel to the rack, so we started putting the puzzle pieces together. The angle of the shaft coming through the firewall to the rack was steep enough that we needed to use three universal joints. Using this setup requires keeping the angles of the universal joints within a few degrees of each other. Too much of an angle on one of the joints will cause binding or give the driver a stiff feel in the steering.

Steering shaft running through the firewall and utilizing 3 U-joints to route to the rack

Our fabricator, Mike “scrooge” Ryan, takes a moment to chase the photographer away

By this point, our fabricator was tired of grinding and decided that we had made enough progress for the day. Our plan is to pickup the next day with the final steering column assembly and start working on the interior components like the parachute release handle and the transmission shifter. Looks like our Grandma project is starting to enter the home stretch run.

For the mufflers, we tapped Flowmaster for a set of their Flowmaster Outlaw Race Mufflers, and some 4-inch exhaust pipe. Flowmaster Outlaw Race Mufflers are a reasonably-priced mufflers that flows monster air, and is in a very small form-factor that makes packaging the exhaust in your race car very easy.

Check out some of the feature below:

• Incorporates sound attenuation rings along the inside of the case
• Does not have a need for packing materials
• Designed for race applications

Flowmaster calls them “Outlaw Race Mufflers”. We call them mufflers? I’m sure they do muffle sound, but the way they are designed, they are going to be loud and they are not going to restrict much, if any, horsepower.

These mufflers feature a straight through design that satisfies the guys at the tech pad, but don’t go trying to passing a police officer with them. They are designed to provide minimal sound reduction, and are more intended primarily for racing situations where a muffler rule is in effect with no specific decibel requirements. Flowmaster sent our mufflers with two straight pipes with a flange on one end for use of our Malibu along with some straight 4 inch pipe.

They won’t do much to limit the noise coming from our 555 Edelbrock/Musi engine, but that is exactly what we like about them! We picked ours up in a 4 inch in and out, but Flowmaster offers them in a 5 inch and 3 inch version to fit most race car exhaust tubing sizes.

First, we bolted the straight pipes up to the flanges off the back of our Lemons Headers’ Collector. It was then that we knew things were going to be tight. Because we had added a few extra bars under the car for more support and safety, getting even the small Outlaw Mufflers to fit was going to be a small challenge.

Mike Ryan wanted to run the car with no mufflers and just some turn out. Thankfully we talked him out of it. This ain’t NASCAR.

We added about 3 inches of pipping to each side of the exhaust after the collector, but before the muffler so that the Flowmaster Outlaws would clear the transmission cross bar.

Mike removed a little of the metal from the cross bar mount as well to give room for the massive 4 inch tubing.

We took a few measurements and shorted each muffler about an inch to fit in front of the large X-bar we had welded in.

Even then we still had an issue on the driver side of the car. So we decided to notch the top on the outlet side of the muffler so that it would clear with no problem.

Fast forward a little bit. We started Grandma up and you wouldn’t believe it. Car sounded fantastic. However, we also realized that we should probably do something to protect our headers and exhaust system for the long haul. Our Lemon’s headers and Flowmaster exhaust were mild steel.

To protect our exhaust system we made a call to Techline Coatings just down the street from us for a coating that would not only protect the metal, but help reduce the amount of heat put off of these components.

They recommended a Thermal Barrier Coating called CermaKrome for our G-Body’s exhaust. Thermal barrier coatings are designed, as the name suggests, to reduce the movement of heat by not allowing it to be absorbed in the metal. The coating can be applied to a variety of surfaces and metals, such as exhaust system components, valve covers, headers, or any other metal that can withstand the 500 degree Fahrenheit cure temperatures. It provides a smooth clean appearance that will not rust, and is effective as a hard protective coating for aluminum parts.

This unique coating is based on a water/solvent system, which requires careful attention to application procedures. To handle the coating, we sent the exhaust over to Olympic Coatings in Escondido, CA to make sure it was done right. We had used Olympic before, and we knew the quality of their work.

Once the exhaust was there, the team of Olympic sandblasted all of the components in order to prep them for the coating process. After a few quick shots with the spray gun, our system was set up to cure.

After the curing process was over, the headers and exhaust were polished to a chrome like finish. Makes sense – now we know where this coating gets it name from.

Now our exhaust is ready to handle temperatures up to 1600 degrees with no problem at all. Not that our system will ever reach that temperature given the coatings qualities. And because the coating was applied to both the inside and outside of the tubing, there are even more benefits. With the surface smoother inside, exhaust gas velocity is increased. Which means that scavenging effect that happens inside the exhaust is increased – moving more hot air out quicker.

That’s all for Project Grandma today, look for more next week!

You sit in the stands, anxiously awaiting the arrival of the next pair of performance monsters to line up at the tree. Burnt rubber and high octane racing fuel permeate the air at the drag strip, as the two cars produce billowing clouds of white smoke that only seconds before were expensive slicks. They line up and rev the engines, and even from 100 yards away you can feel the bone rattling, ground shaking, and eardrum bursting roar of the 1,000 horsepower engines.

This symphony of mechanical synchronization is the result of headers built to perform in the upper echelons of the racing world. But the use of large racing headers can produce problems all their own, especially on stock chassis and engine vehicles. Potential problems range from fitment to ground clearance issues, and they may even make the simplest tasks such as changing spark plugs a major problem.

This is the issue facing Project Grandma. The need for good fitting race headers.