1badeagle

iTrader: (9)

I have a 87 notch with a iron 370 swapped into it. I'm awaiting a front mount 76mm kit. I'm curious what gear I should be running in it? I am running a 275/40/17 tire on the rear an a t56 transmission. It currently has 3.31 gears in it. The gears are way to tall for the current cam only ls1, but I'm not sure how it will be with the boosted setup. I'm shooting for a 650whp daily driver that will rarely see track time because no cage.

Thanks

zapp109

iTrader: (13)

I think that will be fine check this out

http://www.f-body.org/gears/

just select 1998 M6 and fill in tire size and gear

Ryans99ls1

iTrader: (16)

I think your gears are perfect. youll be able to take 4th gear to approx 140mph @6k rpm on a 26" tire. They will the load the turbo well and its gonna come into boost and hold it. if you switched to a 3.50ish gear, at 6k youll be more around 130mph with a 26" tire.

i use 6krpm as a reference because thats where i shift with a stock bottom end. with your motor being forged, youll obviously spin higher which means youll get more mph out of each gear. With 650whp in a foxbody, youll be over 140mph in the 1/4 mi and you dont want to be shifting into 5th gear. 3.31s are perfect.

1badeagle

iTrader: (9)

Cool. Thanks guys. The car is around 2700lbs with me in it. I am also shifting at 7200.

Ryans99ls1

iTrader: (16)

wait you bought chris's car correct? If so, im glad it got a turbo 370!

1badeagle

iTrader: (9)

Yes I did. Bought it and dropped alot of cash and weight lkl.

1badeagle

iTrader: (9)

I guess I'm just used to my current dd that runs like 2600rpm in 6th at 65mph. This car does like 1300 at that speed and gets the cam surge pretty good sometimes.

Ryans99ls1

iTrader: (16)

That thing has a GTO trans as well doesnt it? Pretty sure the gearing was tighter(or at least different) in those t56's

1badeagle

iTrader: (9)

Yes it's a mn12

stevieturbo

With that sort of target power and setup, somewhere around 3.5 would work very well. If you're still pulling 7k with boost, that's 140+ in 4th without too much difficulty

Although the current 3.31 would still work well, especially as the vehicle is quite light