My car is spot on for trap speed considering the rwhp & weight of my car. If you were to search the forums about a year ago when I was predicting what my car was going to run with the new blower, you'll find that based on weight and rwhp I was predicting the car would run 12.30's @ 111 mph, and that is right where I ended up once I finally got to our local dragstrips to verify.
My car (with me in it) weighs 3,650 lbs. Here is how much rwhp is required for a 3,650 lb car to hit various trap speeds, based on solid math.....
- 105 mph requires 290 rwhp
- 106 mph requires 300 rwhp
- 107 mph requires 308 rwhp
- 108 mph requires 317 rwhp
- 109 mph requires 325 rwhp
- 110 mph requires 334 rwhp
- 111 mph requires 344 rwhp
- 112 mph requires 353 rwhp
- 113 mph requires 362 rwhp
- 114 mph requires 372 rwhp
- 115 mph requires 382 rwhp
My car trapped just shy of 112 mph (111.93)
and put down 351 rwhp on a Mustang Dyno, so I not only have the dyno sheet, but timeslips to back it up.
91frppgt, if your car makes truly makes just 252 rwhp and traps at 108 mph, then it would have to weigh just under 3,000 lbs. Or, the dyno you used grossly underestimated your car's rwhp (which is my gut feeling here). Or, as you mentioned, track altitude may have something to do with it. Our local track is 250' above sea level, but its Density Altitude is often 1000-2000' above sea level. Maybe your 108 mph trap speeds were done at sea level (or Density Altitudes well below sea level on a cold day with a high barometer reading).