I am thinking about 3.42ish-3-73 this is an M6 car...i my sping the eng to 6500rpm...

What are you running for gears

 

I am planning on putting a ATI D1-SC in my Z this summer and that may make me change down to some 3.42's, but as of now I have got 3.73's and they work great for the suspension and power I have (420 RWHP, drag suspension). When I put some slicks on at the track, it took 5300 rpm before it would stop bogging the motor! However again, after adding a good 200 rwhp I might need to drop back down to some 3.42's myself.

 

depends on the goals... for a driver, what kind of cam? if you're running a big cam and want to take advantage of 6th gear cruising at 70mph, you'll likely want to keep the 3.73s.

If it's a track car, your goals are different and you'll probably want more speed out before you top out 4th gear...

 

well this is going to be a car that i would like to drive every day...the cam is a custom..but the spec's are close to the cc306 cam with .600 lift...made for a blower set up...what would be the big diff with 3:42/3:73.....sorry still lost on witch way to go???

 

with that size of cam and you want to keep it a daily driver, you'd probably want to keep the 3.73s to get some use out of 6th gear. You actually want to run a slightly higher RPM to keep from surging/bucking at low rpm in 6th on the highway.

 

I say 3.73's ...but it really depends on variables, check this out ....a lot of it's about what speed you want to achieve in which gear concerning the finish line. For example, for a given combo you may choose to stay away from lower gears so you don't have to shift to 4th (or 5th) right before the end of the track ....anyhoo ...check this calculator out:

https://www.camaroz28.com/calcs/index.shtml (4th one down)

 

The general rule of thumb on most forums is:
M6 - 4.10
A4 - 3.73

 

Not on blown cars.

Jerry

 

Jeremy, figure out what size tire you plan to run and what mph you plan on doing. If you run a 28" tall tire and plan on running 135mph traps at 6000rpm in 4th gear then you'll need x.xx gear. I was planning on 3.73's with that cam JFYI...

 

I am thinking of 3:73 as well....and a 28" tire, .....thanks

 

Im running 4.11s in a 9 inch with an m6 on et drag radials. I still have a few hundred rpms before topping out 4th gear. Cruising rpms arent that bad and makes for some fun driving on the street

 

Definitely look at the calculators on this board. I run a mild cam and love the 3.42's. I went from 4.10's to 3.42's and the car is so much better on the street. My cam is the CC218-230-114.

I agree with some of the others that you may want the 3.73's with a large cam. I don't feel the 3.42's would work all that great with a big cam and 6th gear at 70.