Sticking it in the back is something most turbo guys don’t believe in. As devices driven off of exhaust energy, only a madman would think that mounting a turbocharger behind the rear axle is a good idea. Conventional wisdom says that rear-mount turbo systems just shouldn’t work, and the message board goons will tell you that they’re for idiots. Nevertheless, Jarred Shepard is the one making all the haters look like fools in his 2002 Camaro SS. With a 91mm huffer mounted where the stock muffler used to be, this fourth-gen rips 9.01-at-153-mph e.t.’s at the track. And that’s in street-legal trim with a full interior, A/C, stereo, and power everything, thank you very much.
In all fairness to the Internet goons, mounting a turbo in the back of a car is far from the ideal layout. As exhaust makes its way from the cylinder heads to the car’s posterior, thermal energy that should spool the turbo literally goes up in the air. On the flip side, it’s much easier to package a massive hairdryer in the back of a car than it is to stuff one under the hood, especially in the cramped confines of a fourth-gen. Granted, a rear-mount turbo arrangement is a compromise between efficiency and packaging, but Jarred’s figured out a way to make it work. “The biggest challenge is retaining heat in the exhaust system, because more heat equals more air supply,” he explains. “In addition to wrapping the snot out of the exhaust pipes, I had Forced Inductions build me a custom turbo that combines an 88mm turbine wheel with a 91mm compressor wheel. With these mods and the right sized A/R ratio, the turbo spools up instantly.”
Before Jarred got hooked on rear-mount turbos, his first foray into the world of fourth-gen F-bodies was a far less radical ’96 Z28. After porting the heads, upgrading the camshaft, and slapping on the usual bolt-on mods, the lure of the LS1 materialized in the form of an ’02 Collector’s Edition Trans Am. Seeking the kick of forced induction without the underhood packaging complexities of a traditional front-mount turbo system, he decided to give a rear-mount STS turbo kit a shot. “That got me addicted to rear-mount turbos, and before long, I installed a bigger 72mm turbo and got my car to run 11.0 at the track. I wanted to be the first fourth-gen with a rear-mount turbo in the 10s but didn’t want to sacrifice any streetability,” he recalls. “Everyone kept telling me that cars with rear-mount turbo systems can’t run as fast as front-mount turbos, but I wanted to prove them wrong. After cracking the stock LS1 block, I built a forged 408ci motor, upgraded to an 88mm turbo, and modified the cold side piping and oil supply. Unfortunately, I ended up wrecking the car before I got a chance to run it at the track.”
As determined as ever, Jarred replaced the Trans Am with an 2002 35th Anniversary Edition Camaro SS, and picked up right where he left off. Realizing that he was pushing the limits of the project much further than anticipated, he enlisted the services of Late Model Racecraft (latemodelracecraft.com) to built his turbo terror. The LMR crew started by swapping out every salvageable aftermarket component from the Trans Am onto the Camaro. Seeking a higher rpm combination that would run better with a big turbo, Jarred opted for a new 390ci motor based on a GM iron block. Likewise, he upgraded to a custom 91mm Forced Inductions huffer. To ensure that the driveline doesn’t scatter in the wake of the Camaro’s blistering 1,425 rear-wheel horsepower, the motor is hooked to a Century Transmission 4L80E and a Moser 9-inch rearend.
It wasn’t too long ago that quadruple-digit power required an exotic, full-race suspension setup, but that’s not the case anymore. Getting the Camaro to hook is a stock-style torque arm suspension featuring a UMI K-member, Panhard bar, and front and rear control arms. To prevent the chassis from twisting up like a pretzel under the massive heaps of turbo torque, a 12-point rollcage encases the passenger compartment. With an AMS 1000 boost controller ramping in just the right amount of psi, the Camaro pulls 1.31-second 60-foot times and 9.01-second e.t.’s at the track. Equally impressive is how the fourth-gen chassis manages to plant all that power on 275mm-wide Mickey Thompson drag radials.
Consider that Jarred’s original goal was to build a legit 10-second street car, but what he actually ended up with is a legit 9-second street car. It’s safe to say that the Camaro has more than exceeded expectations. Even so, he’s quick to point out that there’s more performance left in the combo. “If I took some weight out of the car, it would run solidly in the 8s, but I want to keep it comfortable and street legal. To the best of my knowledge, this is the fastest rear-mount turbo fourth-gen out there,” he explains. So there you go, rear-mount turbo haters, who’s the chump now?
Running 10s wasn’t enough. I wanted to run 10s in a real street car while keeping the rear-mount turbo setup.
Owner: Jarred Shepard, Reston, Virginia
Vehicle: 2002 Chevrolet Camaro SS
Type: GM Gen III small-block
Displacement: 390 ci
Compression Ratio: 9.0:1
Bore: 4.030 Inches
Stroke: 3.825 Inches
Cylinder Heads: AFR 225cc cathedral-port aluminum castings
Rotating Assembly: Callies 3.825-inch forged steel crank and rods, Diamond pistons
Valvetrain: Factory GM lifters, rockers, and timing set
Camshaft: Custom LMR hydraulic roller (specs classified)
Induction: Edelbrock Victor Jr. intake manifold, custom elbow, Fast 92mm throttle body
Power-Adder: Forced Inductions 91mm turbocharger, custom air-to-air intercooler
Fuel System: MagnaFlow fuel pump, Aeromotive pressure regulator, Bosch 120 lb-hr injectors
Ignition: GM coil packs, MSD plug wires, NGK spark plugs
Exhaust: Factory exhaust manifolds, STS turbo piping
Output: 1,425 rear-wheel horsepower
Transmission: Century Transmission 4L80E overdrive, Neil Chance torque converter
Rear Axle: Moser 9-inch rearend, 41-spline axles, and 3.50:1 gears; Detroit Locker differential
Front Suspension: UMI K-member and control arms, QA1 coilovers
Rear Suspension: UMI control arms, Panhard bar, and subframe connectors; BMR torque arm; QA1 coilovers
WHEELS & TIRES
Wheels: Billet Specialties Street Lite 15x6, front; 15x10, rear
Tires: Mickey Thompson Sportsman 26x7.5x15, front; Mickey Thompson ET Street Radial Pro 275/60-15, rear
Carpet: GM Black
Paint: GM Bright Red