My freak of nature car?

[Mustang302]

Tonight i went to the track for the first time of my life, i was scoring high 12s at 121(street tires). My car recently dynoed at 485rwhp, and keep it mind it weighs 3600 lbs with me in it(full wieght 94cobra with full road race supsnesion). Anyways, i have 4.10s in my car because of my OLD setup, and havent had the time to get it switched over to 3.55s yet. Anyways, I didnt want to switch into 5th gear, so i kept the tach going at the end of the 1/4 at the 121mph i was taching 6500rpms. But on my last race of the night, i went 12.3 at 126.3, i tached close to 7 grand. Now, im kind of curious as to WHY my MPH went so damn high with only about 400 more RPM. i have a STOCK blower pulley on my novi 2000. Was it because i was spinning it so DAMN fast that it made THAT much more boost?!?!

P.S- before i get lectures on revving my motor that high, its built for it :bonk:
http://www.fourvalve.com/cobra/cobra.htm

[fanglemeister]

Your numbers look close, remember the 1/4 mile traps don't measure your terminal velocity, they measure your average velocity across the last few feet of track. For terminal speed, using your 275/35-18 tires' specified diameter of 25.7 inches:

with 4.10 gears in 4th gear:
120 mph = 6432 rpm,
130 mph = 6968 rpm,
140 mph = 7504 rpm.

It is very difficult to keep a roller cam combo moving properly above 6500 rpm - best check with Anderson to see what they say about your valvetrain's expected longevity when going north of 6500 with your setup. If the drag racing is just for testing purposes and your main intent is to run open track events, you would be better off with a taller gear....

with 3.73 gears:
120 mph = 5851 rpm,
130 mph = 6339 rpm,
140 mph = 6827 rpm.

with 3.55 gears:
120 mph = 5569 rpm,
130 mph = 6033 rpm,
140 mph = 6497 rpm,
150 mph = 6961 rpm.

Another option is to switch to 275/40-18 tires, which are 26.7 inches tall, would gain you back a few hundred rpm at any given speed.

With 3.55 gears and 275/40s @ 26.7" tall, in 4th:
120 mph = 5360 rpm,
130 mph = 5807 mph,
140 mph = 6254 rpm,
150 mph = 6701 rpm,
160 mph = 7147 rpm.

Warning: do NOT go WOT in 5th gear making this amount of power, unless you really like rebuilding T5s.

BTW according to my calculation
121 mph 1/4 @ 3600# = 497HP,
126 mph 1/4 @ 3600# = 562HP.

You had some good air that night!