So alot of you know I have been planning on installing a 6spd allison for the past year or so. I like the idea of having as many gears as possible to get great acceleratioin and mileage at cruising speeds.
The allison has good gear ratios and is designed for a diesel application not to mention will handle my twin turbo'd engine with very minor mods. the only problem is I have been waiting on the electronics to control it for over 6 months now and I am getting tired of waiting, not to mention I dont think this bone stock 700r4 is gonna last long with my motor. Oh yeah, I will probably have to severly mod my trans tunnel to fit the allison.
The 4l80/85 is a good trans in my opinion with the proper internals and converter not to mention it already has several options for electronic controls. I can install a pcs controller and have 2 different shift programs and I think it will handle my little motor after a proper build. The downside is that it will be expensive to build the 4l80/85 for ultimate reliability with my motor and get a properly selected converter, I would imagine I could rack up a $5000 bill quickly for a complete setup. I could always do it in stages as money allows though, converter and electronics first then build the internals later on.
As for getting more gears out of the 4l80/85 I have thought of installing a gear vendors behind it. I could have a .59 overdrive for excellent cruising rpms at 70mph for optimal mileage but still have great acceleration, I could even bump up to a 3.55 gear instead of the 3.08 or 3.27 I have now. I have pcs looking into a way to program their computer to make the gear vendor shift automaticly for me instead of having to push the button everytime I want to use it. I have also considered looking for a 4l80/85 from a newer model chevy van with a duramax since they come with that style trans instead of the allison.
Can anyone tell me the difference between the 4l80e and 4l85e?
The gear ratios are
1.93 (GV o/d)
1.15 (GV o/d)
0.78 (GV o/d)
0.59 (GV o/d)
I would probably never use the gear vendors to spilt gears only to have the extra overdrive gear, I just wanted to show you all the gears possible.
So what do you guys think? Which one?
Either way I wont be doing this for a little bit longer but I hope to have the truck running soon and I know the 700r4 wont last long so I need to get something in the works that will last and I refuse to have my truck down for several months again waiting on trans electronics for the allison. On the flip side if the 4l80 sounds like a bad idea I will wait for the allison.