mdstitt

I am looking for some help deciding what transmission to use. I have a 1956 Chevy truck that will have a LY6 with some modifications (cam, intake, hedders). I'm not sure whether to go with a 4L80E or a 4L65E. Vehicle weight is estimated between 3000-3400. The LY6 will be starter engine with possible upgrade to a LS3-416ci at a later date, or possibly adding a turbo to the LY6.

GMPP recommends the 4L65 for engines up to 370ft-lbs torque, then they sell it as a connect and cruise package behind the LS3-480hp which makes 475ft-lbs. even the stock LS3 makes 424ft-lbs.

It seems the 4L80 could be installed without modification and take some abuse. The 4L65 may need some help. What do you guys suggest?

Thanks in advance for your help.

NOS LS1

iTrader: (3)

I am running a Built Stage 2 4L60E in my Camaro LS2 404 ci with no problems.

Im sure there would be some modification if you were going to install a 4L80E.

4L80E would be a stronger trans but you would probably also need a , Harness adapter, flexplate & maybe even a custom length Heavy duty driveshaft & a strong rear end for all that xtra power that you want.

You should do your home work first & do plenty of research before you start your trans project. A built 4L65E would probably be the most cost effective trans....but the 4L80E will take more abuse.


Johnny at "Extreme Performance Transmissions" can build you a killer stage 3 or stage 4 4L65E transmission. He can ship anywhere. This guy does great work !

Heres a link to Extreme perf. transmissions...
http://www.xtremetransmissions.com/

Heres another link with some good 4L80E swap info....
The 4L80E looks like alot more work...

https://ls1tech.com/forums/automatic...l80e-swap.html

mdstitt

Actually, I think that would be the other way around. The LY6 would have a 4L80E behind it in trucks and vans, so going with a 4L65E would require harness changes, flexplate and other modifications.

This truck is a ground up custom, so I am setting up the chassis based on one transmission or the other. Rear end is a Currie 9+ with 31 spline axles and a Detroit Locker. Rear suspension is an Alston's Chassisworks 4-link so those are not an issue.

My thought was that the 80E could probably be used in it's stock form with a warmed LY6 but can the 65E be used stock behind that power level?

The only reason I am considering a 4L65E is the size of the transmission. I would rather not alter the floor if I can avoid it.

Thanks for your advice.