Next-Gen Boost: Testing Whipple’s Gen-5 Cobra Jet Supercharger

If you’ve been following along on the Boosted Coyote project, you already know we started the project with Livernois Motorsports and Engineering “rebuilding” Ivan Korda’s 5.0-liter Coyote engine into their Race-Series long-block. As such, the engine is now capable of handling well into the four-digit horsepower range.

Built for strength, the Race-Series Coyote engine has a Darton-sleeved block, Livernois Powerstorm forged I-beam rods, and heavy-duty pistons, which put compression into the 11.5:1 range. The ported heads flow solid numbers with the larger 1.500-inch intake and 1.262-inch exhaust valves, even with the use of the stock camshafts.

With a 2.9-liter Whipple Gen-3 supercharger on the car, the engine outran the fuel system on its first dyno pull, which led to a full fuel system overhaul. The next trip to the dyno saw the combination max out the boost available using the stock-diameter crankshaft pulley and the smaller 2.75-inch-diameter supercharger pulley for the Gen-3 Whipple, without reaching the 1,000-horsepower goal.

That presented a fork in the road for the project: Option one was to drive the Gen-3 blower harder to pick up the 125 wheel-horsepower needed to achieve the project’s goal. There are two ways to increase boost — swap to the smallest 2.25-inch blower pulley and risk belt slip, or install a larger overdrive crank pulley. Ivan’s second option to reach that 1,000-horsepower mark was to work more efficiently instead of working harder.

Working more efficiently meant swapping the Gen-3 2.9-liter supercharger for the newly released Gen-5 3.0-liter Whipple supercharger, which boasts more power at the same boost levels, due to a total redesign. Dustin Whipple, Vice President of Whipple Superchargers, was confident we’d be able to surpass the 1,000-horsepower goal with the new Gen-5 supercharger and the OEM crank pulley.

Looking at the entire Gen-5 unit, it’s apparent at first glance that this is an all-new design, and doesn’t share much — if anything — with the previous generation of Whipple superchargers.

New Generation Efficiency

We’ve all heard the saying, “work smarter, not harder.” That is precisely what Whipple had in mind when designing the Gen-5 supercharger. When engineering the Gen-5 supercharger, several design goals had to be met. “We had to be better than our competition, in a similar package constraint, meet our peak efficiency goals, and do that all at our price target,” says Whipple. “We met and exceeded our goals.”

While that previous statement is succinct, it belies just how much effort went into the Gen-5’s redesign. “For us to leap forward in technology with the next evolution of the twin-screw, we needed to break down the old design and start over,” Whipple explains. “We had maximized the traditional 3/5 rotor supercharger combo. The Gen-4 is a great option for all the 2.9-liter based supercharger systems we offer, but it is still based on an early Lysholm design, although we changed virtually every part of it.”

The most significant change from the Gen-4 (along with previous generations of the 2.9-liter superchargers) to the Gen-5 is the rotor blade count. Going from the three-blade and five-blade rotor combination to a new three-blade and four-blade rotor arrangement changes the whole flow dynamic of the supercharger.

“We also increased the rotor helix for better sealing,” explains Whipple. “We made the rotor larger in diameter and shorter [in length], giving us a better length-vs.-diameter ratio. Then we updated the rotor shaft design, along with new rotor seals and a new locking procedure, so the rotors can’t move after timing. That also required an all-new housing, bearing plate, and oil cover. So, really, nothing was carried over from the previous design.”

Here you can see from the CAD overlay of a Gen-4 (red) and Gen-5 (yellow) how much larger the Gen-5 is in key areas, while still fitting within the same packaging constraints.

The Gen-5 supercharger feeds from the front, which has been a feature of the Whipple superchargers since the early days — as opposed to the rear-feed design found on other superchargers. In addition to redesigning the rotors, Whipple designed a monstrous new 150mm inlet (dubbed the “Crusher”), which increases flow capacity and reduces the likelihood of cavitation of the inlet charge at full boost. “Rotor-profile technology and airflow management have advanced at a very rapid rate,” Whipple says.

While all of those components combine for a more durable, more powerful supercharger, there were physical size considerations to be made in the design process as well. “We had to leave clearance for the larger pulley sizes for stock-engine, lower-power options on vehicles,” Whipple explains. ”Also the ability to clear the OEM hood and [physically clear] the direct-injection system that the 2018 and up Mustang applications have.”

While that sounds very Coyote-specific, the Gen-5 supercharger wasn’t designed as a Coyote Mustang-specific supercharger. “It was just timing,” says Whipple. “The 2018 Mustang required a lower supercharger and a smaller intercooler to clear the DI system. Instead of sacrificing on intercooler capacity, we took the opportunity to make the new supercharger fit the Coyote. There are lots of new Gen-5 products, including different displacements, coming very soon.”

No Performance Tradeoffs

With the totally redesigned supercharger system and extra 100ccs of displacement, the Gen-5 Whipple’s performance isn’t a tradeoff of improved low- or high-end performance, but rather an expansion of capabilities on both ends of the spectrum. “The screw compressor has a very wide efficiency range; we’re talking the 6 psi to 30 psi range,” says Whipple.

“The low-end performance stayed very similar to the 2.9-liter Gen-4 at low boost and RPM levels, but the top-end performance has increased as well. Higher-flowing applications where more supercharger RPM is required, the gain is at both low-RPM and high-RPM. The higher the RPM you spin it, the bigger the gain.”

A lot of time and effort was put into making sure restriction is minimized while flow capabilities are maximized. From the 150mm "Crusher" front inlet to the extensive CFD design of the race inlet tube, everything has been gone over and optimized to perform.

Looking specifically at the 3.0-liter Gen-5 Whipple for the Ford Coyote application, since that is what we are working with, the improved efficiencies over the previous generations of blower should be incredibly noticeable, even without additional boost.

“With Ivan’s mod list, I expect a 100 to 150 rear-wheel-horsepower gain at the same boost over the Gen-3,” says Whipple, confidently. “If it were comparing to Gen-2, it would be closer to a 175- to 225-horsepower gain. If you wanted to spin [the blower] to a higher RPM, it would make an even bigger gain. Due to the cooler air, the combination can safely run more boost due to the increased resistance to knock.”

Whipple mentioned that Ivan’s engine build was about as ideal of a combination as it gets for the new Gen-5 supercharger kit. “A stock engine on 91-octane gas will only see small gains from switching to a new Gen-5 over a previous-generation supercharger. Modified motors running higher blower speeds, with the increased airflow, is really where the Gen-5 shines. The more airflow required, the bigger the gains,” he says.

The Cobra Jet Kit

In addition to the Gen-5 supercharger upgrade, which in and of itself has much larger intercooler cores (there are three intercooler cores used in the new, larger standard intercooler system of the Gen-5) over the previous-generation Whipple systems, Ivan opted for the “Competition Kit” which comes equipped on the 2019 Ford Cobra Jet.

“The Cobra Jet kit is identical to our standard Gen-5 kit, but with one-inch-thicker intercooler cores and bigger inlet and outlet water fittings. It’s the same rotors, bearings, shafts, tensioner, housing, etc,” explains Whipple.

Another feature that sounds minor on paper but is quite significant in reality — both in performance and ease of installation — is the Competiton Kit’s upgraded water-flow

The only difference between a standard Whipple Gen-5 kit and the “Competition Kit” used on the Cobra Jet are the three thicker intercooler cores and the larger water inlet and outlet ports on the supercharger case. Ivan opted for the increased cooling capacity as an extra safeguard in his combination.

“Essentially, there is no such thing as too much flow through the cores, but there can be too much through the heat exchanger,” Whipple explains. “If you have endless amounts of cool water, the faster you pass it through the cores, the better [intake charge] cooling you will get.”

However, due to the laws of thermodynamics, passing heat between two mediums — such as in an air-to-water intercooler system — heat flows better one way than the other. “Running the water through the heat exchanger at the front of the car, you need time for the water to be cooled by the ambient air. Thus you want it moving fast through the intercooler cores, but slower through the heat exchanger. So there’s a balance,” Whipple explains.

Plumbing The System

To meet the increased water demands and strike the desired balance of heat transfer, we sourced a few other parts used as part of the Cobra Jet’s intercooler system, which aren’t included with the Whipple kit. Since the Cobra Jet is a drag-race-specific vehicle, it doesn’t use a water-to-air heat exchanger system to cool the water flowing through the supercharger. Instead, an ice tank from Watson Racing is used in place of a heat exchanger.

A heavy contributor to the Cobra Jet program, Watson builds many parts specific to the Cobra Jet. Having that knowledge, it also adapts those parts, and the theories behind them, to street cars. It has done that with the ice tank system.

Rather than just running ice water, which only has to last for a single eight-second pass in the Cobra Jet, this is a street system, which needs the ability to continuously cool the supercharger system during street driving. But with Ivan’s frequent trips to the dragstrip, the benefits of an ice tank at the track can be a huge benefit.

Watson recognizes this and makes a two-part kit for standard (that is, non-Cobra Jet) S550s, which relocates the battery with a direct-fit relocation kit, and places an ice tank in the stock battery location. When we say stock location, we’re talking down to bolt-hole placement.

The Watson Racing parts fit like factory, which makes sense considering they make these parts for Ford's Cobra Jet program. The only modifications we made were drilling out the 1/2-inch NPT fittings, and having Dynospeed weld on -16 A/N bungs to have a complete one-inch intercooler cooling system.

In addition to the massive seven-inch-diameter fill hole, the lightweight aluminum reservoir adds more than three gallons of fluid to the supercharger intercooler system. With the larger ports and increased liquid capacity of the system, it only makes to upgrade the pump as well. Again we turned to a supplier for the Cobra Jet program.

The Stewart Components E2512A electric water pump was initially developed for the supercharged 5.4-liter Ford GT engine program and later sourced for the Cobra Jet. It has a computer-controlled brushless motor, full one-inch-diameter inlets and outlets, and flows 25 gallons per minute with only a 12-amp draw. Watson Racing sells the same pump bracket used to install them in the Cobra Jets, which happen to fit perfectly in all S550s.

Once again, a factory fit thanks to Watson Racing’s bracket specifically for the Stewart Components EMP intercooler pump. This is the same setup used in Cobra Jets. The Stewart water pump was initially designed for the Ford GT 5.4-liter supercharged Four-Valve program.

That one-inch-diameter inlet and outlet is an important spec, as they are the same size on the supercharger as well. To physically plumb the system, one-inch (or A/N-16) fittings and lines are required to not prevent restrictions in the system.

If you’ve looked at A/N fittings lately, you’ve probably noticed that -16 fittings aren’t exactly common. To make life easy, thanks to its insanely large selection of fittings — both -16 and otherwise — we turned to Fragola Performance Systems. In addition to all of the 90- and 45-degree fittings, Fragola also had the -16 T-adapter and -16 weld bungs we needed, as well as -16 Push-Lite fittings to ensure everything in the system was one-inch.

Plumbing of the Gen-5 competition system's coolant lines is an undertaking. Working with -16 line is markedly more difficult due to its size. Also, fitting selection can be a problem in such large dimensions. Thankfully, Fragola has an extensive lineup of -16 fittings and the tools to assemble everything, making life much easier.

To compliment all the fittings, we went with Fragola’s recommendation for its Premium Nylon Race Hose. It features a 500-psi working pressure, with a working temperature of -40 to 300-degrees Fahrenheit. The hose is lightweight and matches up perfectly with the 2000-series hose ends we’re using. There were also several sections where Fragola’s -16 synthetic rubber Push-Lok hose  8000-series Push-Lite fittings were used as well.

To make sure everything went together smoothly, Fragola also sent over its -16 double open-ended AN wrench. Made from heat-treated aluminum for the most compatibility with aluminum fittings, each end of the wrench has a different opening angle for access in hard-to-reach spots. They also included a set of magnetic aluminum A/N fitting vise jaws to hold the fittings securely without any chance of damaging the fittings.

One final issue Ivan had to address was fitment under the stock S550 hood. Whipple spent significant effort in the design phase to ensure the standard intercooler has no clearance problems, but the added thickness of the upgraded intercooler core meant he would need a solution. To rectify the situation, Ivan ordered a pair of BMR adjustable-height motor mount brackets. However, the half-inch of additional clearance just wasn’t enough, which meant he would hit the dyno sans-hood

As you can see, the multiple inlets and outlets make for quite an array of fittings needed. One of the reasons for all of the complexity is that Ivan added the Cobra Jet ice tank, which is usually run without a heat-exchanger. Combined with the standard Whipple heat exchanger, this makes for a supercharger cooling system with the best features of both designs.

Spinning The Rollers

As we have done in the past, we headed to Dynospeed Racing in Memphis, Tennessee, to see John Bonner and have him strap the car onto his Dynojet chassis dyno. We gave Lund Racing‘s Jon Lund, Jr. a ring ahead of time to talk about tuning changes for the new blower, What he said threw us for a loop.

He’d look over the datalogs for us, of course, but didn’t feel there would be any additional tuning necessary from the previous session with the Gen-3 supercharger at 20 psi. “The PCM only knows incoming airflow via what the MAF sensor is reading and inputting,” Lund explains.

“The way the PCM converts the MAF signal to an airflow value, to then determine the desired injector pulse-width to meet the target air-fuel ratio, is via the MAF Transfer function. That is just an X-vs.-Y curve of MAF frequency vs. Inferred Airflow in lb/min. If the injector data is correct, then a decently accurate curve can be generated based on dialing it in using the closed-loop fuel trim system, which all 2011-and-up Fords use.”

Surprisingly, all the testing was done with the same tune loaded in the Lund Racing nGauge as we had when we made the 875 horsepower pulls with the Gen-3 blower. That’s a testament to the quality of Lund’s tune.

“Because we’ve tuned a few of these combos to higher boost levels, we have repeatable MAF curve data to use that has resolution from bottom to top. So, when Ivan’s MAF sensor is seeing more MAF Frequency due to more boost or airflow, it will automatically see the proper amount of inferred airflow via the calibration. The background logic will convert that to proper injector pulse-width to hit the target AFR. It’s fool-proof when done properly,” Lund says

Once again, we filled the car with Renegade Race Fuel’s Pro E85 Ethanol fuel. After its performance in the first round of dyno and dragstrip testing, we wanted to make sure we had precisely the same fuel as before. Pro E85 is 85-percent ethanol with 15 percent premium cut alkylates for an R+M/2 octane rating of 100.1.

Even though we were using a new barrel of Pro E85, it was chemically identical to the last barrel. That’s one of the benefits of using Pro E85 as opposed to pump-E85. No batch-to-batch variance means there is no need to worry about the fuel side of the tune changing at all.

Besides the 100.1 octane rating of Renegade Fuel’s Pro E85, the batch-to-batch consistency is a huge benefit to anyone running big-power E85 combinations. This is our second barrel from them, and there was absolutely no difference between them.

With that out of the way, it was time to put the 3.25-inch pulley on the Gen-5 and see what happened. Watching the boost pressure during the run, the car surprisingly made slightly less peak pressure (15.87 psi vs. 16.13 psi) with the same 3.25-inch pulley but made 66 more peak horsepower (888 vs. 822). Also interesting to note, the Gen-5 made more power at 15.87 psi with the 3.25-inch pulley, than the Gen-3 did at 19.49 psi with the 2.75-inch pulley.

While that’s cool and all, we were most interested in what the 2.75-inch pulley was going to do. After letting the engine cool for a bit, the pullies were swapped, and the car was fired up again. This time as the car spun the rollers, the boost level crept slightly past the previous peak (19.49 psi) for about 0.7 psi more than before (20.20 psi).

Less boost but more power? The 3.25-inch pulley test was pretty telling of the increased efficiencies incorporated into the Gen-5 system. But, the real numbers we were after were with the smaller pulley on it.

As the rollers spun down and the computer calculated all the numbers, the graph popped up and there it was — 1,002.22 horsepower. That number is using the more restrictive SAE correction factor as well, ensuring it is a legitimate 1,000 horsepower number (if we were to apply the looser STD correction factor, power would jump to 1,026 horsepower).

Breaking the four-digit barrier was a great accomplishment, but we also need to look at the before-and-after numbers between the Whipple 2.9-liter Gen-3 and 3.0-liter Gen-5. With a previous best of 875 horsepower with the Gen-3 and 1,002 horsepower with the Gen-5, that’s a 127 horsepower increase.

The smaller 2.75-inch pulley made slightly more boost (20.2 psi vs. 19.5 psi) but picked up 127 horsepower on the same pulley sizes and tune as the Gen-3 blower. Whipple called the gains ahead of time, and while some were skeptical, there it is in black and white (and red and blue). With the SAE correction factor applied, no less!

Let’s lay all the data out there. Yes, the Gen-5 is 0.1-liter larger and yes, the Gen-5 made 0.71 psi more boost. But 127 additional peak horsepower with only a 35 lb-ft boost in peak torque tells you that the majority of the gains were made in the high-end efficiencies. Looking at the dyno graph, Whipple’s earlier quote, “the more airflow required, the bigger the gains,” is borne out.

We calculated the blower speeds at a touch over 20,000 rpm at 8,200 rpm engine speed. Whipple says there is absolutely no concern about a Gen-5 at those speeds. In fact, if Ivan wanted to get wild, an overdrive crank pulley would net him even more substantial gains. However, we have to remember this is a street car — a 1,000-horsepower, nine-second street car — thanks to the Whipple Gen-5 supercharger.

Dyno Comparison By The Numbers

3.25-inch pulley 2.75-inch pulley
2.9L Gen-3 3.0L Gen-5  2.9L Gen-3 3.0L Gen-5 
Peak Boost 16.13 psi 15.87 psi 19.49 psi 20.20 psi
Peak HP 822.54 888.00 875.73 1002.22
Peak TQ 630 (est) 665.60 702.79 737.64

Test performed with stock-diameter ATI Super Damper; SAE Correction Factor applied

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About the author

Greg Acosta

Greg has spent fifteen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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