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.”
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.
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.”
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)
“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.”
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.
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.
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.