JasonC

Im seriously considering swapping my 94 Z28 6 speed to a TH350 trans. The car has 4.10's in the rear, and I love being able to cruise at highway speeds at somewhat low rpms. I know that changing to a 3 speed auto is of course going to increase the rpm while in top gear, but by how much? At say 70 mph? I dont mind changing the rear end ratio if need be, but would prefer to spend that money elsewhere. I just dont want this thing screaming down the road while just cruising. My mods are listed in my sig, heads and larger cam going in next week......


BTW, the car sees 99% city driving with the occasional short highway trip.

Z28/2002

iTrader: (27)

My TA is around 2800 at 55 mph with a TH350, 4.11s and a 27" tall tire

Z28/2002

iTrader: (27)

You'll be at about 3700 RPM with a 26" tire


Play with the link below

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

pddye

iTrader: (14)

i'm on a 28" tire with a 3000 stall, 3.73's and its not bad at all at 55. Now get up around the 70 mph mark then its a little much. It will definately kill your gas milage too. Which didn't mind me much since I've put a total of 2000 miles or fewer on the car this year so far.

JasonC

I really dont put too many miles on the car a year either, maybe 5-6K. If I have to change the gears back to a 3.42 or a 3.73 to make the car more driveable than I will. The car currently has 26-inch tires and I dont plan on going bigger any time soon, even with dr's or slicks.

For a stall In thinking maybe 3500rpm? I have always run manual trans cars, so this will be my first experience with an auto. My main reason for doing this is that I had knee surgery a few years ago and the clutch pedal is killing me having to shift all the time in town, so an auto is pretty much a must-do swap.

I know the cam pretty much dictates where the stall needs to be, so heres the specs on the cam I am installing. Give a shot at recommending a stall rpm..... 242/248, .576/.600, 115 lsa

Z28/2002

iTrader: (27)

A converter between 3500-3800 would be perfect for the car.

Do you plan on spraying it?

JasonC

Im debating between nitrous or a blower. More than likely Ill end up just spraying it though.

LS1Formulation

iTrader: (13)

If you want to know what kind of RPM it will turn, go out and drive it in 4th gear and add about 600 RPM to that figure to account for slippage. 3rd gear is 1:1 in a TH-350 and 4th gear in a T-56 is 1:1 as well.

blkbird_WS-6

iTrader: (14)

Bingo!!!

Z28/2002

iTrader: (27)

Since you plan on spraying the car make sure the converter is built to handle nitrous. It won't be as fast on motor but will pick up when you shoot it

JasonC

Yeah I know about getting a converter for nitrous. Ive already shopped around and picked one, just have to order it and the flexplate. Im picking up a trans from a reputable local builder later this week. Then I just need to pick a shifter and order a crossmember from BMR and it can all go in. Should have it swapped in next month.

Z28/2002

iTrader: (27)

Good Luck