axehead

when racing in the 1/8th i have to shift my M6 into 4th a few feet before the finish line. i'm running 4.11's in the rear & don't want to go lower as it is a street car, the first gear ratio in my tranny is 2.97 which when multiplied with my 4.11's give me a 12.21 ratio to lauch with. i've played around with a power speed calculator & it tells me that if i run a 3.55 ring & pinion that i will cross the finish line at the top of 3rd gear.

would going with the 3.55's be the better choice? i still would have a 10.53 ratio to lauch with, or would it kill my 60'?

i have a 150 shot of spray that could get me out of the hole.

kazman

A taller rear tire will accomplish the same thing as a gear change. What are you currently running on the back? Are you bracket racing?

axehead

no bracket racing, just test-n-tune. mickey thompson et street radials are what i run & i want to keep them. they are stock size & mounted on stock wheels, the sleeper look. with the 4.11's its giving me a good 60' time but causing an extra shift (from 3rd to 4th), with the 3.55's i wouldn't have to shift that last time but am concerned about losing to much of my 60' time.

which one will make me faster?

PHINES LT1

what about a 3.73? also what mods do you have and what are your shift points/limiter set at? might be able to get away with a carrying a few extra revs across the stripe.

axehead

i shift at 6200, & if i try to use "extra revs" its way to much. 3.55's would be what i would need to cross the line at 6200 in 3rd gear. i'm just not sure if i would lose to much 60' time.

Stephen 87 IROC

You can cross the finish line at or a few hundred rpms over your shift point. If you use 3.73, you can hold 3rd gear for that last short distance before you cross the finish.

If you dropped the gearing down to 3.42/3.45, you would cross the finish just before you hit the shift point.

Your "stock size" tires are probably 26" tall. Keep the 4.11's and go to a 27 or 28" tall tire.

My starting line ratio is 8.55 and this spring I'm changing it to 8.04 but I also have a lot more torque than you do. I'm trying to tame the wheel spin.

axehead

i'll check but i don't think they make a drag radial that size that fits my stock rim, i like the sleeper look. maybe i should just be content with what i have, its pretty quick for a stock looking car.

Kevin Blown 95 TA

I wonder how much time you lose shifting vs. how much you might lose with one less gear. If you have a peaky power band, then you need to shift it more.

axehead

thx man, that's the way i've been trying to word it. you did it a lot better than me.

AL SS590 M6

You might be suprised the tire companies offer a wide variety of sizes. I know that Hoosier makes a DOT slick that fits stock rims and is 27'' tall. Put some on a spare set of rims for race day.