Steeda Boosts The One-Off GT350X With Whipple



If you aren’t familiar with the Shelby GT350X, it is a Steeda creation commissioned by the crew at Dream Giveaway for a raffle that will award this car and a Classic Recreations vintage Shelby GT350X to the winner. (Photo Credit: Steeda Autosports)

As we recently shared with you, Steeda Autosports built a one-of-a-kind Mustang, dubbed the Shelby GT350X, for the 2017 Dream Giveaway. The final modification delivering the performance to back up its Steeda suspension upgrades and visual modifications was a Whipple supercharger designed specifically for the Shelby GT350/GT350R.

“Steeda Autosports believes in giving back and we support many different charity causes as well as our military. When the opportunity came up to participate in the 2017 Mustang Dream Giveaway, it was just a natural for us inasmuch as we design and manufacture more S550 performance upgrades than anyone else in the marketplace,” Bob Adams, Business Development Manager at Steeda Autosports, said. “In particular, the GT350 platform responds exceptionally well to our upgrades — effectively elevating the car to substantially greater heights, while remaining docile enough for comfortable everyday driving.”

A one-off GT350 project needs big power and Steeda selected the Whipple 2.9-liter supercharger for its GT350X project. Matt Bouyea, technician at Steeda, started by removing the front fascia.

Of course the aforementioned supercharger system was the crown jewel of the modifications on this one-of-a-kind Shelby GT350X. This 2.9-liter twin-screw supercharger is supported by a complete kit from Whipple, including an intercooler system, fuel injector upgrades, a supporting PCM calibration, and more.

“We utilize the Whipple 2.9-liter blower on all of our Q750 Steeda StreetFighters that we manufacture, and its overall performance has clearly demonstrated its superiority — especially with its outstanding low-end torque and volumetric efficiency,” Bob enthused. “Hands down, it is far better than roots-type superchargers that are sold today because it provides more power per pound of boost than any other system that is available with outstanding reliability.”

Perfect Opportunity

The 2.9-liter has been a leader on the S550 platform. — Dustin Whipple, Whipple Superchargers

“We were approached about this project and thought it was a fantastic opportunity to reach new customers and thought it would be an incredible promotion to give away a GT350,” Dustin Whipple, president of Whipple Superchargers, said. “The 2.9-liter has been a leader on the S550 platform. The displacement, efficiency and overall package are perfect for the GT350 platform. It requires no cutting, welding, or grinding. You can just bolt on massive, reliable power and go.”

“The system is almost identical [to the Mustang GT system], the biggest difference is the throttle body and calibration,” Dustin added.

To clear the way for the supercharger, Matt removed the factory air box, induction tube, and intake manifold. He disconnected the factory fuel lines and removed the stock intake, fuel rails and injectors as one assembly. Then he reoriented the harness for the knock sensors and taped up the connectors for the Intake Manifold Runner Controls, which aren’t used with the blower. Be sure the Intake Air Temperature sensor is free and clear, however, as it will need to be connected via an extension harness.

Steeda technician Matt Bouyea bolted the Whipple supercharger and its supporting hardware to the Shelby GT350X in the company’s Pompano Beach, Florida, shop. We will hit the highlights here, but Whipple provides a highly detailed instruction manual for those who want to tackle the installation themselves.

“The overall installation is really straightforward for a properly qualified automotive technician with professional tools,” Bob Adams of Steeda Autosports said. “The Steeda/Whipple Supercharger kit has been thoroughly engineered for fitment that mirrors OEM fit, finish and reliability and when completed — it just looks right in the engine compartment.”

With the valley free from obstruction, Matt drops the Whipple lower intake manifold, which includes the intercooler, into place after installing the O-ring seals on each runner. After checking to ensure there are no wires or hoses in the way, he followed the pattern in the instructions and torqued the fasteners, first to 88 in-lb and then to 106 in-lb. Moving to the front of the GT350X, Matt installs the heat exchanger, intercooler fluid reservoir and intercooler pump.

Casting A Spell

Of course, fitting the hardware together is important, but Whipple also provides the electronic support to cast a boosted spell on the Voodoo 5.2-liter engine. That support is in the form of a carefully crafted custom calibration flashed into the factory PCM.

Matt lowered the Whipple 2.9-liter into place, ensuring that the bypass valve seated properly and there were no hoses or wires between the blower case and the lower intake. With the twin-screw blower in place, Matt torqued the blower fasteners to 15 lb-ft in the prescribed pattern. He followed up by torquing the fasteners to 22 lb-ft of torque. You will need to install the shorter heater tubes included with the Whipple kit and reorient the hoses as described in the instructions.

The Steeda/Whipple supercharger performance package when combined with our various Steeda G-Trac suspension upgrades completely transforms the GT350. — Bob Adams, Steeda

“The Whipple calibration is done by Ford engineers using factory tools, allowing an unprecedented ability to make the car drive like stock, while extracting maximum power,” Dustin explained. “The system uses its own supercharger modeling, something the standard aftermarket tunes can’t do. Therefore the calibration and software works with the supercharger versus against it like normal stock calibrations. All factory safety functions and diagnostic features are maintained.”

In practice, the supercharger turns the high-winding Voodoo engine into a completely different animal. The Whipple blower adds a low-end punch that the stock 5.2-liter lacks, but it still keeps pulling all the way to the top of its stupendous redline.

“In a single word, ‘breathtaking,’ and I have been around performance vehicles for over 25 years,” Bob added. “The Steeda/Whipple supercharger performance package when combined with our various Steeda G-Trac suspension upgrades completely transforms the GT350 to an unprecedented level of performance. A normal GT350 just can’t compare to the level of performance we have been able to attain with this package. Power, handling, and drivability are unsurpassed.”

In order to add the supercharger to the front engine accessory drive, Whipple supplies a bracket with idler pulleys and a spring-loaded tensioner. After pressing on the support stands, Matt bolted the bracket to the timing cover and torqued the the 10mm bolts to 25 lb-ft and the 8mm bolts to 18 lb-ft. With the blower drive pulley bolted on, Matt used a large wrench to move the spring-loaded tensioner and installed the drive belt.

Steeda Shelby GT350X Mods

• Brushed-aluminum GT350X grille emblem

• Color-coded Lightning Blue “supercharged” side rocker stripes

• Color-coded “supercharged” hood callouts

• Steeda G-TRAC Suspension fender badges

• Color-matched GT350X emblem on the rear fascia

• Body-colored rear fascia

• Body-colored rear spoiler with Lightning Blue over-the-top striping

• GT350X sill plates and dash plaque

• GT350X wheel center caps

• Raised white-letter Nitto NT-555 G2 tires

• GT350X callouts embroidered on the front seats

• Steeda two-point G-Trac brace

• Steeda billet oil separator

• Steeda rear independent rear suspension subframe brace

• Steeda independent rear suspension alignment kit

• Steeda caster/camber plates

• Steeda clutch helper spring

• Steeda adjustable rear toe link

• Steeda billet aluminum integral/vertical links

• Steeda rear sway bar

• Steeda rear camber arm brackets

• Whipple 2016-2017 Shelby GT350/GT350R supercharger system

As you’ll see on the dyno sheet, the gains are significant, but in the case of a full vehicle build like the Shelby GT350X, this car needed the mods to apply that newfound power.

“Power means nothing without traction and handling — and the Nitto high-performance tires are an absolute requirement so that the car can hook up perfectly and lay the power to the pavement,” Bob said.

“We have been partners with Nitto for over 20 years, and do extensive tire testing on the track, street, and drag strip with them in the quest of always evolving the best high-performance tire for the Mustang platform,” he added.“The Nitto NT-555 G2 selected for this car is a maximum-performance tire engineered to complement the high horsepower of the vehicle and we believe it is the perfect tire for all-around performance.”

For more on what these companies have to offer, you can visit the official Steeda Autosports site here and Whipple Supercharger here.

Getting closer, Matt installs the Whipple heat shield and filter, transfers the factory electronics and stepper motor to the 132mm elliptical throttle body, and bolts up the throttle body and inlet tube. While you could run the factory 80mm throttle body on the blower, postitive displacement superchargers flourish with as little inlet restriction as possible, which is why Steeda upgraded to the bigger Whipple throttle body.

Wrapping un the install by tapping into the stock fuse box to power in the intercooler pump and fans, the GT350X is just about ready to rock the rollers with its newfound twin-screw boost. Before you run the car, but sure you filled the blower’s gear case using the supplied lubricant. The Whipple blowers are shipped dry and running them without lube will cause damage.

With the Whipple install completed and the included calibration applied to the PCM, Matt strapped the Shelby GT350X to Steeda’s in-house Dynojet chassis dyno to confirm its performance improvement.

Adding the 2.9-liter Whipple supercharger definitely delivered the X rating to this one-off Steeda Shelby GT350X project. The Voodoo 5.2 picked up 253.12 horsepower and 130.56 lb-ft of torque at the rear wheels with nothing more than the blower and the companion calibration — and that was in the sticky South Florida summer air.

Article Sources

About the author

Steve Turner

Steve Turner brings decades of passion and knowledge in the world of Ford performance, having covered it for over 20 years. From the swan song of the Fox Mustang to the birth of the Coyote, Steve had a front-row seat.
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