Lethal Performance boosts its GT350’s Voodoo 5.2-liter with a Whipple
By Steve Turner
Photos by Steve Turner and courtesy of Lethal Performance
After we got over the initial excitement of learning about the Voodoo 5.2-liter engine, there was one evil thought that came to mind. What would it be like with boost? Fortunately we know people who think the same way. When the crew at Lethal Performance acquires a new Mustang project, it’s a fait accompli that the car will eventually receive a Whipple supercharger and for the Lethal Shelby GT350 that time has arrived.
With just Lethal cat-delete pipes, a JLT cold-air intake and a Lund Racing tune, this combo put down 501 horsepower and 416.62 lb-ft of torque to the rear wheels on the Dynojet at Power by the Hour in Boynton Beach, Florida. With nitrous and a corresponding calibration it spun the rollers to the tune of 621.26 horsepower and 592.21 lb-ft of torque at the wheels.
Regular readers of the SVTP Front Page have followed the progression of Lethal’s Shelby from its dealership burnout to its 500-horsepower bolt-ons to its record-setting first 10-second pass on nitrous. With those milestones in place it was only natural to take the next step and supercharge the Voodoo 5.2.
“We’ve always upgraded our cars with Whipple’s newest offerings so it really wasn’t much different with this one,†Jared said. “Just look at how well our 2015 GT did with boost. Now imagine that with a higher revving, higher compression motor like the 5.2-liter Voodoo engine.â€
Lethal opted to install the same 2.9-liter Whipple supercharger that it has successfully run on its 9-second 2015 Mustang GT. The 3×5 rotor combination inside this blower is said to offer more airflow and under-the-curve performance than its 2.9-liter predecessors with a rear inlet. This unit features a high-flow front feed, a jackshaft drive and it bolts to a dedicated lower intake with an integrated, high-efficiency intercooler. The blower looks great in Avalanche Gray. While black is the standard finish, but you can for custom colors on the blower and manifold for $600. If you would rather have both polished, that’s $800.
Of course doing so meant adapting Whipple’s existing Coyote kit for the GT350 platform. While the engine shares the same basic architecture as the Voodoo engine, some of the support systems in the new Shelby created challenges. Chief among them was calibrating this combo to work with the GT350 software, which was handled by the pros at Lund Racing. However, there were also several hardware hurdles that the crew at Power by the Hour also had to leap over to install the kit.
“There were a few things we needed to do to make the standard Whipple 2015+ GT kit fit the GT350. For one the GT350 uses a fuel rail pressure sensor where the GT doesn’t. Although Whipple has since made an adapter for that we ended up welding a bung into the fuel rails supplied with the kit to allow the use of the rail sensor,†Jared explained. “We also had to relocate the remote oil cooler as that’s in the same location where the Whipple intercooler tank reservoir and pump get mounted. Lastly, the blower wouldn’t fit under the stock hood without the help of some UPR adjustable motor mounts. Once we put those in, we had plenty of good clearance and could still run the stock hood liner.â€
Power by the Hour main man Jake Long removes the factory induction and intake manifold. Then he reorients the harness for the knock sensors and tapes up the connectors for the Intake Manifold Runner Controls, which will no longer be used with the supercharger system. He also plugs the Whipple extension harness into the Intake Air Temperature sensor, then swapped the factory restrictor into the heater hose supplied in the supercharger kit.
Now for some purists this might seem like sacrilege, but admit it. Even the leave-it-stock crowd has to be a little curious about how the high-revving 5.2-liter engine would respond to boost. It turns on that with the proper supporting equipment and careful calibration, this engine responds quite well to forced induction.
You can watch the Whipple-boosted GT350 run on the dyno right here…
Because the GT350 utilizes a fuel-rail pressure sensor and the Mustang GT does not, Power by the Hour had to mod the Whipple fuel rail by welding on a bung for the sensor. While the rails were off they received a set of Injector Dynamics ID1000 squirters that are fed plenty of E85 by fuel pumps boosted by a JMS FuelMax.
“I’m still kind of shocked about how much power this car made with the blower. It’s actually funny listening to all of the people on the Internet and forums saying the high-compression, flat-plane-crank engine wouldn’t handle the boost. Then you have your real sources who actually calibrate these cars for Ford and have extensive hands on experience with the 5.2-liter saying the exact opposite,†Jared said. “Of course we’re not going to throw 20 pounds of boost to this thing, but with some good fuel like E85 and the best in the business—Lund Racing—tuning it we achieved some amazing numbers. Comparing our 2015 GT with the Whipple that made 700 rear-wheel horsepower at 11.50 psi you have to be impressed with the GT350 making almost 120 more rear-wheel horsepower at the same boost level. An 819 rear-wheel-horsepower GT350 is pretty bad ass in my opinion and that’s on a completely stock motor.â€
Jake swaps the O-rings from the stock manifold to the Whipple intercooled lower. Then he torques the fasteners in the pattern prescribed in the instructions, first to 88 in-lb and then to 106 in-lb on the second pass. After swapping over the sensors from the stock intake, Jake installs the new injectors and Whipple fuel rails.
As you might expect, the next step for this fledgling combination is a trip to the drag strip. After driving this car with nitrous, driver Jeremy Martorella was quite confident that the supercharged version would run well on the 1,320, and Jared has some lofty goals for the car.
“We’re really not sure what to expect at the drag strip. I know that we went high 10s at 600 rear-wheel horsepower with a slipping clutch. So, I guess anything with a 9 in the beginning sounds reasonable,†Jared surmised. “The only issues we’re going to battle are that we’re running that factory clutch until McLeod finishes up with the unit it is building for us. In addition to that the gearing in the car isn’t ideal for the strip, as the car wasn’t designed for that. We shall see I guess.â€
Naturally, we’ll keep you updated as the Lethal GT350 makes its next moves, so stay tuned.
Make certain that the bypass valve is seated and no hoses or wires snuck in between the blower and the lower manifold before you start bolting things down. Follow the pattern in the manual and torque the blower down first to 15 lb-ft and then, on the second pass, to 22 lb-ft of torque.Whipple’s robust bracket allows the addition of the supercharger drive pulley to the factory six-rib Front Engine Accessory Drive. Jake pressed the support stands into the bracket with a vice, then he bolted on this idler pulleys and the spring-loaded tensioner. The bracket bolts to the timing cover without any modifications. Just torque the 10mm bolt to 25 lb-ft and the 8mm bolts to 18 lb-ft.The Whipple kit includes this cleverly designed intercooler reservoir, which is installed low on the core support behind the bumper cover and mounts the intercooler pump nearby so there’s little chance of the pump cavitating. This setup uses a remote fill that’s attached to the filter heat shield in the engine compartment. The only trick on the Lethal Shelby GT350 is that this car features an oil cooler that normally occupies this spot. As such the Power by the Hour team had to relocate the oil cooler.Naturally Lethal chose the optional twin-fan unit for this install, but the heat exchanger itself is 60-percent larger than the one employed in Whipple S197 Coyote kit. It works to tame boost temps by cooling the 1.3 gallons of coolant circulating through the system.To maximize the system’s power potential, Lethal opted for Whipple’s high-flow, elliptical throttle body. They also augmented the ignition system with a set of colder Brisk RR12 spark plugs to better handle the increased cylinder pressure.Here’s a combo that’s sure to attract attention any time the hood is opened. The Whipple is fed by its own high-flow inlet, heat shield and conical filter. Just a reminder that the superchargers are shipped dry, so be sure to fill the blower gear case to the full line. If you forget and run the blower dry, it will cause damage.
To ensure the fuel pumps deliver a strong, reliable fuel supply Lethal chose one of JMS Chip & Performance’s JMS PowerMAX FuelMAX V2 fuel pump boosters which can deliver up to an 85-percent increase in fuel delivery.The Power by the Hour team wired the JMS FuelMax in between the factory Fuel Pump Driver Modules and the fuel pump wiring. Another harness is routed to the front of the passenger compartment to plug into the throttle pedal. These boosters can be activated via throttle angle or boost pressure and the rate of voltage increase can be ramped in and ramped out.After Power by the Hour tweaked and installed the kit and all of its supporting hardware, the tuning gurus and Lund Racing took over, strapping the car to the PBH Dynojet and dialing in a custom calibration to allow the stock PCM to accept its new boosted configuration.Pullied for 11.62 pounds of boost the Whipple 2.9-liter supercharger increased the peak power of the Voodoo 5.2-liter by 344.36 horsepower over the stock engine and an impressive 318.67 over the same engine with bolt-ons and E85. Likewise, the peak torque jumped by 208.66 lb-ft over the stock engine and 188.78 over the bolt-on combo.We took a look at a sampling of the data from the stock and bolt-on 5.2-liter combo and the new boosted combo. No matter how you slice it, the Whipple 2.9 and the GT350 really get along. The blower adds triple-digit gains throughout the powerband. It should be fun to see what this combo does at the drag strip.
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