Hello, guys. I just bought a 96 SSEi. And after changing the water pump, installing a new radiator and replacing the sir intake hose that was split, I strapped her down to my Dynojet chassis dyno.
With the air filter removed and the air box open, it made 206whp @ 6000 and 259wtq @ 2500. This car has 146,000 miles!!!!!!! The interesting thing is it made no less than 200whp from 5200-6000!!!!!!!!!!!!! Most GTPs I've dynod only made 194-197whp. I can see the Bonne exhaust is far superior to the GTP.
A few notes on dyno tuning. All Bonnevilles have a top speed limiter. On the '96, it'* 129mph. If a car is being tested in third gear,the engine will not redline. That'* why tampas car only showed 180whp. Another thing to know is when a transmission shifts on the dyno, the software sees the split second slowing and acceleration of the shift and shows it as a loss and gain in power. Erroneously high numbers will post b/t 1-2 and 2-3. Also, when the engine hits the rev limiter, it will bounce and sometimes show a slightly higher number.
My car was dynod in second gear by putting it in manual 2. With the 4T60, the trans will not downshift to 1st if the shifter is in second. (It will also start in second gear). You can't dyno in third until you remove the speed limiter thru the software calibration.
1988 Grand Am SE 2.0 Turbo
1996 Bonneville SSEi Twin-Charged