im sure this has been asked many times, so sorry if a repeat
right now i am running an old school turbo 400, with a switch pitch converter
(dual stall, 1300/3000)
the problem i have is the car wants lower rear gears to really perform,(6.0 w/procharger) and along with that will come high rpm's at highway speeds, and the flowmaster drone, lol
so were kind of back to looking at OD trans-i have a 2005 4l80e, which has the bolt hole at 12 o clock, which is good-im pretty sure the 1st gearing is still 2:48, as compared to a lower gear in the 4l65e-i like the lower gearing in the 65e, but seems lot of reliability problems with the weaker units
of course, i guess they sell the 2:75 gear sets for the 80e, but not a big jump
i feel i would need at least 3:73's in the rear with the 2:48 1st, but 4:11's would be better, but not sure what the final od+ lock up rpm would be(28" tire)
a 3:73 with the 65e would prob be great-any thoughts on this(would need to switch to mech speedometer also)
(when i built the car, chevelle, i mocked up a 80e in case of a switch)

 

If you have over 600HP, the 4L80E would be a better choice. I use a 4.10 gear with the 65, and a 28" tall tire and put on alot of miles each year. The RPM's are around 2100 in lock-up @ 70 MPH. I think you'll be fine with the taller tire. As far as the launch ratio, the 65 is quicker with the 3.07 over the 2.48, but the strength is unmatched with the 80. If I didn't own a trans shop, I would choose the 80. My car is a constant test bed to get consistant longevity with the 65, and until a better input drum is made, this choice is a hard one for the guys in the 500-850HP range for heavy performance. No need to switch to a mechanical speedo. I'm working on a friend's 69 Chevelle with a 582" and putting a 4L80E behind it. The motor dynoed 809HP-745LBS. He is using BS3 and has 2000CFM TB. He will shift at 6500RPM, and is running a Dana 60 with 4.10 gears with 29.6" drag radials. With the OD, we can be more aggressive. Good luck!

 

Mightymouse runs out of gear with his 80e and actually lets it shift into OD at the track...thats one bad Transformance 80e!!!

 

thanks-what are you running the speedometer with if not mech-some kind of conversion box? mine is a 69 chevelle also, 6.0 with a procharger/intercooler

 

we run ours from the stock pcm but they do make conversion pieces to do it...i have seen it with th400 and 4l80e on the supras

 

So a 4l80e is better than the 60e whats the diffrence?

 

I keep blowing my 4l60e mines keep hit 7000rpm don't know why.

 

They're two totally different transmissions. Sounds obvious I know but if you want a specific answer theres going to be a lot of typing involved.