'08 GT500 Dyno Results ~ Before & After Mods

Before (factory stock, 2415 miles, 91 octane, 12/01/07)
Max. Tq: 414@4475, Max. Rwhp: 394@5400
After (Steeda CAI, JBA 3" cat-back exhaust, custom program thru Xcal2 & dyno tuning, 2468 miles, 91 octane, 12/03/07)
Max. Tq: 472@4350, Max. Rwhp: 502@6275
Work was done at JBA Racing in San Diego (same people who did R&D for Super Snake exhaust and tune) on a Dyno Dynamics Dynamometer I did the cat-back exhaust after the base runs, then did the intake and tune today. Total cost: $2121.79 (including base run) ~ that's less than $20 per "horse" gained at the rear wheel.

 

Note that 414 was torque, rear wheel hp was 394. Air/fuel ratio on this car was out of spec (should be near 11.5) starting at about 2500rpm and went as rich as 9 above 5500. After tune air/fuel was 11.5 +/- .2 thru the same range to redline. I read on another forum that Dynojet Dynos read about 10% higher than other dynos -- that's why I noted the dyno used and the shop. Comparisons between different cars on different days in different places should not be made, there are too many variables. For example, dyno results will be higher on a cold, damp day than a hot, dry day. Same for high vs low atmospheric pressure. There's more air in a cubic foot of air on cold, damp, high pressure days, and more air means more hp. What's significant is more than 25% rear wheel hp gain with simple, relatively inexpensive, modifications.

 

Very likely. Elevation has an effect, too. Remember that the amount of air in a cubic foot of air changes based on several factors. I learned that the onboard computer adjusts air/fuel ratios based on a long list of factors including cat temp (which was the reason my base line air/fuel ratio was rich). The real value for Dyno results is in work on one car, before and after mods are made. They can also be useful to compare between cars when the runs are made on the same dyno (and operator) on the same day or under very similar conditions.