Mike’s Trans Am has several performance mods installed… a JET Performance 160 degree thermostat, a TCI 2800 rpm stall torque converter, a ram-air hood, a Borla cat-back exhaust system, and 3.73:1 rear gears. However, nobody told the engine management computer that these mods were made.

Dan Bills at Finish Line Performance baselined Mike’s TA at 264 rear wheel hp and 286 ft. lbs. of torque. The car was also running lean, as the air/fuel ration was up near 15:1. When it comes to tuning, it’s all about the air/fuel ratio. The use of a wideband oxygen sensor tells the computer on the dyno what the ratio of unburned fuel is in the exhaust. Too much fuel is termed rich, and too little is lean. With the ideal ratio, the car will automatically make as much power as it can.

Dan Bills uses a software program called LT1 Edit to make changes to the onboard engine management computer. These changes will calibrate the computer to run properly with the modifications on the car. He decreased the temperature that triggers the fans to keep the intake air cooler, then he switched off the traction-control feature that retards timing when wheel slip is detected. Then, Dan added fuel to the delivery curve as needed to straighten out the air/fuel ratio. Dan pointed out that any time you change an intake or exhaust on a computer controlled car, the air/fuel ratio can change!

Repeated software changes and dyno runs allowed Dan to hone in on that ideal 13:1 air fuel ratio, and the horsepower and torque curves responded accordingly. Mike’s Trans Am netted 267 hp and 288 ft. lbs of torque, but the real story is in the curves. Check out the difference in the area between the lowest and best run… all that increased white space translates to more power across the RPM band, especially around 4200 RPM, the car’s shift recovery point.

Dyno tuning is one thing, but the real proof is at the track. After the Finish Line tune up, Mike went out and laid down a 13.77 at 99.83 MPH, a timeslip that was equal to his previous best before the tune up.

After a big burnout and using the performance mode on the transmission, Mike’s TA clicked off a 13.70 at 99.87. That’s the quickest the car’s ever run, but Mike’s gunning for the 13.60’s. The very next run, Mike achieved his goal. He wanted to run in the 13.60’s, and his last pass of 13.66 at 99.83 miles per hour solidly put him there. So far, we’ve been able to knock a full second off this car’s ¼ mile time! It pays to tune the parts you have.

SOURCE

Finish Line Performance

DISCLAIMER: Demonstrations and procedures contained in the V8TV show or website may not provide all necessary or relevant information. Applicable local laws and regulations may vary and should be checked before any project is commenced. Be sure to follow all applicable safety procedures. The Men's Channel and V8TV Productions, Inc. make no warranties, expressed or implied, as to the completeness, accuracy, or practicality of any such demonstration or procedure or any information with respect thereto contained in the preceding program.

© 2005 V8TV Productions, Inc.

Share this link on your favorite social network!