Having experienced the rush of several race cars, we decided to set a goal for our new daily driver: 500 hp and low-11s in a perfect-driving F-body. Too easy-just to slap on a N.O.S. kit and let it be-but we didn't want to worry about flipping switches and filling blue bottles to make this car fast. We were very interested in the STS rear-mounted turbocharger system, though, and Rick Squires explained the ins and outs of the setup and investigated the project's future. That's why we began with a slightly larger turbo than is normally provided in the system kit; the T76 snail is a proven power maker that would allow a bunch more engine upgrades without running out of air.
While it is possible to do the install in 6-8 hours without complication, we are very particular about fit and appearance, so we spent three afternoons on the turbo install alone. The car has a lowered suspension, and it didn't take long to see this was going to be an issue. No matter how we oriented the pipe over the rear axle, it either hit the gas tank or looked like it would drag on the ground. We shortened the over-the-axle pipe almost 2 inches, which required cutting and welding. With the Hooker after-cat system we put a three-bolt flange on our hot pipe that would allow us to hitch the turbo to the existing after-cat pipe. Even after several fitting checks, we got the turbo assembly too far to the driver side, creating more issues.
At this point, it was much easier to modify the tailpipe and air-cleaner hanger than to change the turbo hot pipe. Once the installation was complete we loaded a tune- up that would allow the introduction of extra fuel required while in boost. Rick recommended Nelson Performance, which helped by sending the initial baseline tune to be programmed into the HP Tuners, but instead caused the motor to surge with poor idle quality. We changed the sensors, injectors, and intake manifold, but solved nothing.
Putting several hundred miles on the car in this state brought up other concerns. In a hard rain, spray from 18-wheelers was almost too much. Within minutes the car quickly fell on its face and came to a crawl in the emergency lane. Although the engine idled decently, a touch of the throttle pegged the air/fuel gauge at 10:1 and it would seize. After an hour we could go, but the car quickly came to another halt. Waterproof sock notwithstanding, rain was the issue.
When we disabled the MAF sensor, the engine ran perfectly, but we had to drive without putting the turbo into boost mode. We'd read about the new software and were determined to tune the car ourselves. The latest HP Tuners 2 Bar programs would allow this without the MAF sensor, and provide a much steadier idle and cruise speed. For the fine attitude, I called Keith and Ken at HP, who helped with the new tune. The engine ran flawlessly from idle to wide-open throttle and felt stronger than it ever had. Now the car drives like the stocker. Until you mash the go pedal. Then you better grab the steering wheel with both hands.