Hello you guys, I have couple question I want to get off my back, before doing an LS1-4L60e swap into my 87 rx7. First things first is I have a sbc 350 with a turbo 350 and at 60 miles per hour im cruising at around 6000 rpm, and it majorly sucks, because i have 4.10 gears. I was wondering if the 4L60e would solve this problem, making it cruise around 2500 rpm since the od gear is alot lower than 1:1. Second, how the hell does the tranny knows when am I OD, do i switch it, or the computer does that? And what is my best option, to lower my rpms.
P.S. Rx7 diffs has barely any options to lower gear ratio.

Thank you guys for looking at my post!

 

4th gear in a 4L60E is 0.70. So your RPM will drop to 70% of your current.
Frankly I doubt you are at 6000 rpm at 60 mph unless you have 12" wheels.
Here are two calculator for determining RPM based on tire size, rear ratio and trans ratios:
http://www.wallaceracing.com/gear-speed.php

http://www.f-body.org/gears/
(Use the top left drop-down menu to select "1998 F-body A4" to have it fill in the 4L60E gear ratios.

The computer selects 4th gear like any other gear.

 

Yes 4.10 more like 3500 or so RPM I would guess but yes you would drop 30 percent lower and if you have a computer PCM installed it will tell the trans when to do everything.