MaxStreet’s Supercharged Musi/Edelbrock 800 HP+ 555ci Rebuild
Here at powerTV, we take great pride in our project vehicles. We aim to cater to varying styles of vehicles, combinations, and applications with the utmost of craftsmanship, all while providing real-world knowledge and how-to tips. Following the success of Project Grandma 1978 Malibu, it was time to turn our attention to the next vehicle in our lineup of project cars out in the shop – our Project MaxStreet 1966 Chevy II.
The goal for this project is to achieve upwards of 800 horsepower at the wheels in a package that mixes plenty of grunt with reliability and longevity. Plus it must be able to be driven on a regular basis to the grocery store, up and down the freeway, and everywhere in between.
Our feisty old Grandma laid down some strong mid 10-second quarter mile times during a test session at the Fontana Dragway last season with the Musi/Edelbrock 555-inch powerplant under the hood. Prior to testing, a trip across our DynoJet racked up a count of 521 horses at the rear wheels. Needless to say, this is a very stout and capable combination. But when we made plans to pull the 555 and transplant it into Project MaxStreet, we knew that we’d need to make some modifications under the hood to meet our goal.
In this tech article, we’ll take a look at some of the new components that we’ve outfitted the Musi/Edelbrock bullet with, along with a detailed look at the engine buildup at Pacific Performance for our switch from nitrous oxide to a growling F-2 ProCharger centrifugal supercharger unit.
Back To The Drawing Board
Starting at our installation shop Pacific Performance, also known as Ford Performance Solutions, has all the equipment needed to assemble high quality race and street engines. Duties like a touch up hone, double keying the crank, and even porting the Edelbrock intake manifold were all done under one roof. We have worked with Pacific Performance on projects in the past, and feel very comfortable with them rebuilding our 555.
The Musi/Edelbrock 555 is exactly as the name implies: a partnership between two of the biggest names in the high performance automotive and racing world. Those being veteran racing engine builder and multi-time world champion drag racer Pat Musi, and Edelbrock, whose contributions to the automotive landscape need absolutely no introduction.
The 555 cubic inch crate engine is based upon a Dart Big M Series block and features a SCAT steel crankshaft and H-beam rods with a 10:1 compression ratio, along with an Edelbrock Victor Jr. intake manifold. Out of the box, this baby produces a tire-roasting 675 horsepower and 650 ft-lbs of torque. But once it rolls out of the powerTV garage between the fenders of our Chevy II, it should be pulling quadruple digits at the crankshaft.
Of course, swapping over to a forced induction engine combination requires making several changes throughout the engine – especially in our rotating assembly – to both handle the increased horsepower and stress, but really make our new combination sing to it’s fullest potential.
ProCharger’s F-2 Supercharger
Providing the boost to make upwards of 1,000 horsepower will be ProCharger’s popular F-2 self-contained supercharger unit that’s well-traveled in drag racing and street applications and is more than capable of helping us attain our horsepower goals. The F-2 delivers a tremendous amount of air flow, with great versatility for nearly anything you might wish to do with it.
“The F-2 is the biggest bang for your buck, horsepower-wise. Bolt it up on a well-built small block and it’ll make 1,400 to 1,500 horsepower; and we’ve seen more than that on extremely well-built big blocks. We’ve got guys that run them on the street all day and make 800 to 1,200 to the tire on pump gas,” said ProCharger’s Dave Werremeyer.
Werremeyer went on to say, “I would say out of our F-series, it ranks up there efficiency-wise with probably one of the highest we’ve ever built. It’s the mainstay, as far as upgrade paths. Whether you’re a street guy or you’re an all-out racer, it’s got something for everybody.”
ProCharger F-2 Self-Contained Supercharger
- 10.5-inch volute diameter
- Self-contained oiling
- Ultra-high speed bearing assembly
- Precision ground steel gears
- Supports up to 1,600 horsepower
JE’s Low Compression Forged Pistons
While we could’ve gotten away with the standard 10:1 compression pistons in our 555, it surely wouldn’t have been optimal. JE Pistons designed us a set of low compression pistons that would create a better compression ratio while incorporating the features we needed. The pistons that we’ll be outfitting our 555 with are made from 2618 alloy – the strongest material that JE utilizes for such an application – and are of an inverted-dome design to lower the compression ratio to around 9:1. This ratio is a solid fit for both street and racing use, and is low enough to be run on low boost with pump gas and later switched to race gas with higher boost levels.
This forging design is one that’s specifically designed for the big block Chevrolet, with some added elements to increase its overall strength. The deck thickness is adjusted specifically for forced induction, thus having more material across the crown than would be found in a naturally aspirated engine. Also, the ring locations are altered to make them less sensitive to tuning issues. The top ring is moved down by increasing the top land thickness by .340-inch.
These pistons also include a skirt coating, which is a benefit for street cars in that it takes out some of the clearance needed for the 2618 alloy pistons, also making it quieter at start up. In addition, they use thicker wrist pins to support the cylinder pressure commonly seen in engines with this type of power level. “Basically the top ring has been moved down, the deck has been thickened up, it’s a dedicated big block Chevrolet forging, and it gives you right compression ratio that will allow you to run on both the street and on the racetrack,” said JE Piston’s Sean Crawford.
JE Alloy Big Block Pistons
- 2618 alloy – the strongest that JE utilizes for this application
- Inverted-dome design
- 9:1 compression ratio
- Skirt coatings
Comp’s Custom Grind Camshaft and Ultra Pro Magnum Rockers
We also commissioned the folks at COMP Cams to grind us a custom roller camshaft designed specifically for our supercharged, 555-inch Big Block. Most naturally aspirated camshafts typically have about six to eight degrees of split between the intake and exhaust, however, the camshaft we’ll be employing has a 14-degree split.
“What that does is help you dispose of the excessive heat and cylinder pressure that are caused by the boosted application,” says Chris Douglas of COMP Cams. “We also spread out the lobe separation; the tighter the lobe separation is, the quicker the torque will come on. The supercharger is providing an incredible amount of torque, so we spread out the lobe separation and that broadens your torque band and makes the thing a little more controllable on the bottom end, while helping with the cylinder pressure.”
While a camshaft designed for use in naturally aspirated and supercharged combinations are vastly different animals, supercharged engines and those using 250+ horsepower nitrous systems use a very similar, if not identical, camshaft.
Also from COMP Cams is a set of their redesigned Ultra Pro Magnum steel roller rockers. The web-like design delivers increased strength and rigidity while reducing the moment of inertia and optimizing the dynamic balance. What that means is the rotating end of the rocker is actually lightened to reduce the amount of weight the camshaft needs to move onto the valve tip. We’ll also be using a brand new set of COMP Cams of tie-bar hydraulic roller lifters that have redesigned roller wheels to survive up to 6,500 RPM without any problems.
COMP Cams Custom Grind Hydraulic Roller Camshaft
• Duration at .050 – 248 Intake 262 Exhaust
• Valve Lift – .647 Intake .647 Exhaust
• Lobe Separation – 114 Degrees
Flowing With Edelbrock’s RPM XT Cylinder Heads
As we highlighted in another recent in-depth article, our stout 555 will be outfitted with a set of Edelbrock’s new RPM XT cylinder heads. The Performer RPM XT – or Xtreme – is an all new cylinder head design from Edelbrock that’s CNC ported to attain optimal air-flow for maximum horsepower and torque, and intended for use in high performance street cars and light duty racing applications.
According to Rick Roberts, Edelbrock’s Director of Engineering, the RPM XT falls right in line between a racing and street cylinder head. The casting and port design are new and engineered to be as close to perfect as possible, with a fully CNC ported combustion chamber and CNC porting in the bowl area for a smooth transition into the valve seats. The intake runner entries and exhaust runner exits have also been partially CNC-machined for increased air flow.
Edelbrock’s RPM XT Oval Port Big Block Chevy Heads
- Combustion chamber volume 112cc
- Intake runner volume 308cc (lh) / 325cc (rh)
- Exhaust runner volume 133cc
- Intake valve diameter 2.25″
- Exhaust valve diameter 1.88″
- Valve stem diameter 11/32″
- Valve guides Manganese Bronze
- Deck thickness 9/16″
- Valve spring diameter 1.55″
- Valve spring maximum lift .700″
- Rocker stud 7/16″
- Guideplate 3/8″
- Pushrod diameter 3/8″
- Valve angle 25°
- Exhaust port location +.125″
- Spark plug fitment 14mm x 3/4 reach, gasket seat
- Made In USA
Damped If You Do, Damped If You Don’t
One of the final components in the rebuilding of our Musi/Edelbrock 555 is the addition of a new Big Block Chevrolet Super Damper balancer from the folks at ATI Performance Products. These balancers are designed to prevent torsional crankshaft vibrations and are tunable, rebuildable, and very efficient at all RPM levels. They’re finished in a black zinc chromate finish, with laser engraved 360-degree timing marks that are easy to read even in dark engine compartments.
This new steel-shelled unit that we’ve bolted up to the 555 is designed for superior performance for street and strip applications utilizing a supercharger combo, such as what we’re tackling with Project MaxStreet, and measures the same dimensions as an OEM big block balancer with a 7.074-inch outer diameter. In the weight department, you’re looking at just 8.75-pounds with just 4.5-pounds of intertia weight. With the torque of the boosted setup in mind, the crankshaft has been double-keyed to fit the likewise double-keyed Super Damper that will provide plenty of longevity under the stresses expected on the front end of the crankshaft.
ATI’s Big Block Chevrolet Super Damper
- Tunable and rebuildable
- Double keyed for supercharger applications
- Weighs just 8.75lbs with 4.5lbs of intertia
- Steel shell with black zinc chromate finish
- Laser engraved, 360-degree timing marks for easy reading
So, as you can see, we’re moving right along with the buildup of what we hope will be a 1,000-plus horsepower street and strip terror, and armed with a plethora of high quality and well-performing components we should have no problem achieving that goal. Soon, we will be fitting the 555 into MaxStreet and getting it plumbed. And suffice it to say, we can’t wait to put the hammer down on this supercharged, big block beast. Stay tuned!