Pushing A Coyote Over 1,000 Dyno Horsepower With Twin-Screw Boost

Power adders come in almost as many options as Baskin-Robbins has flavors. Different types of superchargers, turbos, and nitrous all have their own unique powerbands, though none of them pack the boost response punch of a good ol’ positive-displacement supercharger. Amongst those companies is a name that’s synonymous with the Mustang’s heritage, and that’s Whipple Superchargers.

“The advantage of a positive-displacement supercharger is the large amounts of torque produced at lower RPM,” Dustin Whipple, of Whipple Superchargers, explained. “The positive-displacement supercharger pumps the same volume of air every rotation, therefore airflow is very linear throughout the RPM range. This allows you to get near max airflow at all engine RPM versus turbos and centrifugal superchargers, which have a very progressive airflow curve.”

We tested Whipple’s Gen 2.5 Whipple supercharger on our Coyote test mule. The 2.9-liter blower was equipped with Whipple’s 3-inch, 10-rib pulley.

Whipple is family owned and operated company in Fresno, California, since 1987. It also develops the rotors, supercharger housings, and kits in the USA. The company has over great 55 team members and are continuing to grow with lots of new kits and products.

Whipple is on its third generation of the tried-and-true, twin-screw supercharger. Compact in size, this 2.9-liter rotor group still comfortably fits under the hood of S197 Mustangs. The front-inlet design allows Whipple engineers to easily mate a factory-style cold air inlet and decrease the number of bends required to get air into the supercharger. The rotors must be driven from the rear to allow the air to enter from the front. This means a jackshaft system connects between the supercharger drive pulley to the rear gearbox.

A benefit of positive displacement is having positive manifold pressure with the sneeze of the accelerator. As those rotors spin together, they increase the speed and pressure as the air travels between them.

This cutaway helps show exactly what’s going on inside the Whipple supercharger. Air is delivered to the rotors via the front inlet, compressed down, through the intercooler, then back up, and to the runners.

Volumetric efficiency and a low reciprocating drag is the name of the game when it comes to making the most out of your power adder. Making the compressor work as efficiently as possible increases the power per pound of boost and reduces heat. Also having a giant air-to-water intercooler core that fills the entire valley helps increase air density before the valve. The denser the air, the more of that boost you’re able to pack into each cylinder.

The positive-displacement supercharger pumps the same volume of air every rotation, therefore airflow is linear throughout the RPM range. — Dustin Whipple, Whipple Superchargers

When it came to designing its intercooler packaging, Dustin explained, “Yes, one thing we are known for is using every square-inch possible. We found, after using a competitor’s lower half in our Ford Performance package on the S197, there were limitations to the amount of cooling capacity, yet one still had to grind the block! Since we were starting from scratch, we made a core 33-percent larger than the previous design. We opened the water passages up and changed the fin type for lower pressure drop. We also significantly increased the plenum area above and below for better airflow.”

(Top Left) Whipple's Gen 2.5 supercharger was a tweener between their Gen 2 and 3 systems. Now fully converted to Gen 3, the 2.5 included Whipple's new rotor group with the company’s older housing and provided half of the horsepower advantage. The jackshaft system allows for a front air inlet and thus simplifying the air intake plumbing. (Top Right) Our 2011-2014 Mustang kit comes complete with fully assembled hoses at the correct length. Each hose is bagged and labeled separately to avoid any confusion of their placement. (Bottom Left) Also included with the kit is a heavy-duty heat exchanger, fabricated coolant tank, and high-flow intercooler pump. (Bottom Right) New, billet fuel rails are included with their kits and we completed them with Fuel Injector Clinic's 1,650cc injectors. We ran injectors that large because we're running our engine on E85.

The Nitty Gritty

We caught Whipple in between a transition between its Gen 2 and 3 systems and ended up with their 2.5. “The Gen 2.5 was a stopgap while the new housing was being done,” Dustin said. “This featured the new rotor group with revised profile and coating. The newer profile was a enhancement to the Gen 2. We made some big breakthroughs in rotor sealing and clearance distribution. This greatly increased performance across the entire RPM range. The Gen 3 housing further enhances rotor filling and efficiency. Our next upgrade will be even one step further in performance.”

Understanding The Stages

All new Whipple Stage 1-3 superchargers now feature their new Gen 3 housing and rotor group. But there’s no way this is 50-state CARB legal right? Wrong! All complete Coyote based kits are 50-state legal.

• Stage 1: This is Whipple’s base supercharger system . The tune comes with a lower RPM limit, less aggressive calibration and uses the stock 80mm throttle body. ($7,695 retail)

• Stage 2: Still using the stock 80mm throttle body, this stage comes with a pre-programmed fuel pump voltage booster for extra fuel supply, one pound of additional boost, and a more aggressive calibration. ($8,095 retail)

• Stage 3: This system boasts a slightly more aggressive tune up and Whipple’s elliptical 132mm billet throttle body. This is good for an additional 25 horsepower and 15 lb-ft of torque. This means the 91-octane tune up creates 750 crank horsepower on only 10.5 psi of boost! Whipple offers this throttle body in cable or drive-by-wire configuration, utilizing the factory drive motor. ($8,695 retail)

When jumping to the Stage 3 system Whipple includes a new front inlet that is designed for its elliptical 132mm throttle body. “A round throttle body is better but you can’t fit a massive round blade under the hood, nor package around it so one is forced to squeeze it down,” Dustin said. “In the past, we always had a modified oval, which had flats on bottom and top. They had to be massive, 170-plus mm which is incredibly hard to control and idle.”

Whipple offers their billet elliptical 132mm throttle body on their Stage 3 kits to deliver all the air. A drive-by-wire version of the Roval unit accepts a stock throttle body's drive mechanism, but because we were using a Holley HP standalone, we opted for the cable-driven variant.

“In the end, we came up with something in between — an extremely high flowing, very near similar to a round throttle body of equal size, but far greater than a flat-blade-style throttle body,” Dustin added. “Our good friend, Steve Turner dubbed it a Roval (round/oval) which stuck, so now it’s the 132mm Roval, which we now have a 150mm Roval for the next power level. These can drive like a stock 80mm in all conditions, yet make 1,500+horsepower — the best of both worlds.”

Regardless of what stage you start with the system is fully modular. Upgrade to the elliptical throttle or simply change the supercharger pulley, you can lower or increase the power which allows it to fit nearly any application.

Four More Ribs, Please!

“The 10-rib looks great, but works even better,” Dustin shared. “We recommend it after the 3.0-inch six-rib combination. If you need more airflow than that, a 10-rib is the best option. Ideally, most should run the Cobra Jet style version, which pulls the alternator back and runs on the AC belt line. This shortens the length significantly which helps extend belt life.”

(Left) When a 20-percent-overdrive ATI damper is paired up with a 3-inch supercharger pulley, the additional four ribs provided by the optional 10-rib upgrade makes a big difference. (Center) We already had a Meziere electric water pump and we were able to easily swap out to a 10-rib idler pulley. The Meziere pump comes with all the accoutrements of the stock water pump system for an easy installation. This pump will help free up some horsepower but also allow us to cycle water through the engine while it’s off. (Right) The Whipple bracket system comes with numbered spacers to ensure belt alignment is dead-nuts. Also included in the 10-rib kit is Whipple's heavy-duty tensioner for increased belt tension.

Many supercharger kits on the market will use a stock style, cast auto belt tensioner. To take things to the next level, Whipple decided to engineer its own.

“About two years ago we got tired of fighting OEM-style tensioners, which are very affordable, but impossible to control clearances and motion. Since we are tight on space, we have to hold the belt in a very accurate position at all times,” Dustin said. “The cast versions typically don’t have bearings to control rocking, therefore the arm’s motion can sometimes push the belt the wrong direction. This causes many issues including noise and excessive belt wear. We made a very robust, all billet tensioner that looked great and was easy for the customers to install.”

Our Test Specimen

To test the upper limits of the Gen 2.5 Whipple supercharger on a Coyote, we needed to start with a strong foundation. We fortified our Coyote block with Darton dry sleeves by Race Engine Development and then had it fully assembled by MPR Engines. The short-block consists of a new 4340 forged BOSS 302 crankshaft, BoostLine’s all-new 2,000-plus-horsepower-capable forged connecting rods, and 10:1 compression ratio JE Pistons feature an Electroless Nickel treatment along with DLC-coated pins. Since our engine is based on a used F-150 core, our compression ratio came in at 10.6:1 after the heads and block were decked.

The top end of the engine consists of COMP Cams Stage III blower camshafts, valve springs, and retainers, Ferrea supplied the oversize valves that meld perfectly with MPR’s CNC port and valve jobs. The camshafts are locked out with MPR’s lightweight lockout plates and are supported by Livernois billet chain guides, MPR billet oil pump gears, and MPR front chain drive. The 20-percent-overdrive ATI Performance Products damper that’s setup for a 10-rib configuration properly matches up with Whipple’s 10-rib upgrade for maximum belt traction.

Our fully built Coyote was assembled by MPR Engines. Darton sleeves, JE Pistons, BoostLine connecting rods, and all ARP hardware filled the bottom of the block. MPR's CNC ported cylinder heads, Ferrea valves, full COMP Cams valvetrain, and all the billet front drive goodies rounded out our long block.

(Left) Our engine has locked out camshafts and is running off Holley's HP standalone EFI system on the dyno at Westech Performance. (Right) Fill and forget it. Whipple utilizes a self-contained oiling system and only requires the oil to be replaced every 75,000-100,000 miles. A sight glass on the side helps make fluid level checking a breeze.

Hitting the Dyno

We took our Coyote to Westech Performance for our engine-dyno testing. Due to the power levels we plan to make with our engine, our camshafts were locked out and degreed. The lobe separation angle on our Coyote was set a little wider so we didn’t have to turn the motor so high.

We decided to run the system on Holley’s HP series standalone EFI system. They offer a plug-and-play kit specifically for the Coyote. Rocket Brand provided the E85 fuel that’s pumped by Fuel Injector Clinic’s 1,650cc injectors. Whipple’s smallest recommended supercharger pulley is 2.75-inches for the Coyote application, so we decided to test our engine just above that threshold with the 3-inch pulley.

Stratospherically different between our before and after dyno runs. Once Westech had got our air/fuel ratios where we wanted them, we started to add timing and our engine was the happiest with 21 degrees of timing. While we did make 1042 hp on one pull, our average pull ended up at 1028.4 horsepower and 833.3 lb-ft of torque with 20 psi of boost. That’s an overall gain of 492.3 horsepower and 453.6 lb-ft of torque. This means our motor was making 24.6 horsepower per pound of boost. We only needed to spin our motor to 7,200 RPM due to our wider LSA and anything beyond that the boost slowly tapered off. Special shout out to Ken Bjonnes of Palm Beach Dyno for helping out with some tech support during our dyno session!

We were able to showcase the potency of Whipple’s Gen 2.5 supercharger with its 3-inch supercharger pulley on our 2013 Coyote dyno mule. For this looking for the next level of performance from Whipple, don’t fret, Whipple has more in store.

“Yes, 100 percent, we’ve got quite a few upgrades coming that will further benefit the entire Coyote market. Stay tuned,” Dustin added.


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About the author

Mark Gearhart

In 1995 Mark started photographing drag races at his once local track, Bradenton Motorsports Park. He became hooked and shot virtually every series at the track until 2007 until he moved to California and began working as a writer for Power Automedia. He was the founding editor for its first online magazines, and transitioned into the role of editorial director role in 2014. Retiring from the company in 2016, Mark continues to expand his career as a car builder, automotive enthusiast, and freelance journalist to provide featured content and technical expertise.
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