3:91 Gears.

[acammer]

Originally Posted by sean_reaves33

I have a 2011 camaro ss modded : i have 3:91 gears on a upgraded transmission that handles 1000 hp. Got the 2.9 whipple wit the nick Williams 102 boosted TB, makes a difference. headers, cat delete and auxiliary pump which handles 1000hp.
Now CHVYMAC mustang dyno 840 rwhp. It's pretty fast but when i get past 160mph it blows out a lil water while running 170+ and it still be pulling. Tring to figure if the gears are to low to be doing pulls at 150mph? Now if i just press the gas and get to 170mph no problem, but if i do a pull from 150mph then a lil smoke come from underneath the car. Once i slow down smoke stops. Then everything seals back up. No leaks nothing. Therefore i can do pulls up to 160mph no problem. Or do you think its a tunning error? Or engine compression issue. Maybe a bigger cam? Appreciated your feed back..

Stick or automatic car? I'm gonna guess automatic just based on your not talking about selecting a certain gear, and with a stick car you'd be making a 4-5 shift somewhere in the speed range you're experiencing the problem with.

Assuming then that this is a 6L80 car, with 3.91 gears, 28.5" tires (stock height), a triple disk lock-up converter (as would be expected with a power adder car) and a 7000rpm redline (as would be expected with a cammed car) then you ought to be able to see about 175mph in 5th gear. If you don't have a lockup, then you've probably got that 5-6 shift occurring closer to 160mph.

I'm not sure what fluid you're pushing from where, but if it's only occurring at very high speeds and at the 160mph point it makes me wonder if it may be driveline related. If it were something related the engine it should not be so speed dependent. I would want to figure out what the fluid is, and then trace it from there. Have a good look at the transmission vent tube, and other plugs on the transmission case for any damp places. I would not keep making high load pulls with a known leak, it's not likely going to be a self-healing problem, and will almost certainly get worse or have a cascading effect of problems. Transmission fluid is very flammable, and very slippery, and a fire or a loss of traction at high speed due to fluid can be a really bad situation.

Regarding your question about gearing I think that it really depends on your setup. If I've guessed right on this being a 6L80 car, then I would consider a different rear gear ratio if you really like to chase big MPH. A stick cars 3.45 gear with a lock up converter, 28.5" tire, and 7000rpm redline will run 200mph with a 6L80 - that would be my recommendation for anybody going roll racing for big big MPH.