got a stock 4l80e that im going to put in my truck tomorrow, but im still building the 6.0l so whats the 4l80e going to do on my 4.8l? better gas mileage maybe? less performance?

 

It will rob power and slow you down but you can beat on it till the 4.8 dies.

 

what does the 4l80e need done to it to cut down on the power loss?

 

Use a smaller transmission?

It's a physically larger transmission therefor more parasitic drivetrain loss.

 

couldnt have said it better myself

 

ok thanks, but with the 4l80e shouldnt i get better gas mileage with its overdrive vs. the 4l60e?

 

The overdrive is a tiny bit higher than the 4l60e if I my memory serves me correctly so if anything you will get worse.

You're fixing to drop a few $1000 on a new transmission and you're worried about gas mileage? Come on man.

 

the 80 has a taller 1st gear and a shorter OD. You will be slugish off the line and turn a few extra rpm's on the Hwy...... but you can beat the snot out of it, lol. Get a stall to make up for the tall 1st and you will love the closer ratio shifts. Just don't worry too much about mileage.

 

You will wonder when the damn thing is going to start to move. Honestly I went from a very tired and slipping stock 4L60E to a 4L80E with a Transgo HD2 shift kit and stock diesel converter stalling at a whopping 1500 rpms and it didn't feel a bit different power wise. The lower stall does make it wind out a little bit slower but as far as mileage goes its actually up a little due to the tighter converter. In my case my engine makes extremely strong lowend torque. I'm not in love with the lower OD ratio of the 4L80E but knowing its not going to slip is worth putting up with that.

 

With an 80e wouldnt you need to cut down the drive shaft?? Im very curious about this since Im fixing to put an 80e behind my soon build 6.0. Sorry to thread jack