svt99redcobra

ok i just got my 750hp capable tranny into the car two weeks ago, i have been babying the hell out of it durring the break in period. I noticed in my old tranny that 5th gear wasnt really a racing gear but just OD, now 5 gear is right in sync with 4th in my power band and when im cruising im at 2,000 rpms at 55mph. Holy **** thats alot of gas mileage being wasted. I have 410s and in my old tranny doing 80 i was at 2k. What do you guys think. They just put differrent ratios in the tranny since its built for some serious power.

5speedstang

ummmm sounds right with 4.10s. at 55 im around 13-1500i belive and thats with 3.27s at 70 im at just under 2k.

cliffyk

[/align][/align]There's no way you were going 80 @ 2k rpm with 4.10s--with 3.27s andthe stockTremec 3650 2k in 5th is 74 mph, w/ 3.73's 2k = 64 mph, and with 4.10s 2k in 5th would get you rolling only a bit over 58 mph (58.2 in theory).[/align][/align]The stock 3650 5th gear is a 0.62:1 overdrive, I think the T-45 5th is 0.67:1 -- plugging that in to the 58 mph with 4.10s number above we get 58.2 * 0.62 / 0.67 = 53.9 mph; pretty close to the 55 you're seeing.[/align][/align]So, it sounds like your new tranny has a 0.67:1 5th gear same as stock.[/align][/align]

2000GT4.6

What tranmission do you have that is supposed to be rated at 750 horsepower?

cliffyk

I wasn't going to ask, since trannies are rated by torque capacity it had to be some line of poop--a stock 3650 could handle 750 HP, you'd just have to spin the engine at 11k rpm...

racer02GTstang

im gussing you have the tko600... so that sounds right... overdrive in those trannies is like i think .8X or like .68 compared to .64 in the others...

racer02GTstang

mmr builds trannies to hold 750hp by cryotreating them... im guessing this guy got one from them... and from the sounds of it, he went with the tko600 instead of the 500

piledriver

You probably know this, but the 36 in 3650 stands for 360 lbft torque.

cliffyk

Yup, 360 lb.ft. * 11,000rpm / 5252 = 753.99 HP[/align][/align]Actually I don't know if the 3650 is rated for that kind of input speed, with the 0.62:1 5th gear the output shaft would be spinning nearly 18k rpm!!![/align]