98cobrakiller

bought a 01 z28 for my new project. going with a ford 9 in rear end. but having trouble picking a tranny. the turbo 400 was my original choice because of cost being cheaper. however the 4l80e being a 4 speed would be nice if i wanna cruise in it. also not sure what rear gear id have to run in the 1/4 mile. car is going to be around 600whp on 28in slicks or radials and 4000 stall converter. shooting for mid 10s

mrvedit

Sorry no one answered your question, but it a very general topic that has been covered here many times.

Here is a very recent and an older thread on the subject:
https://ls1tech.com/forums/automatic...400-4l80e.html

https://ls1tech.com/forums/automatic...owerglide.html

At 600whp in the 1/4 mile, you should check a calculator, but I'll guess that 3.73 would be right. I think you would exceed 7000 rpm with 4.11.

GMRACER13

iTrader: (1)

For what it's worth, I have a TH400 transmission, 9" with 3.25 gears, ~4400 stall converter and 28" drag radials. I make less than 600 rwhp and run 10.3x's in the 1/4 mile with a 1.4x 60'. My car cruises at approx. 3000 RPM at 70 mph. It's worth mentioning that I have an aftermarket gear set in the transmission which makes my 1st gear ratio 2.97:1 instead of the stock 2.48:1. The car leaves like a car with 3.73 rear gears and a stock transmission but I cross the traps at about 5800 RPM in 3rd, lol.