4l80e vs Allison 1000

[dgrown]

So here is my question is there any advantage to using an Allison over the 4l80e? the wiring in my car is setup currently for a 4l80e the engine is going to be a twin turbo 5.3L which will be going in here this spring. So was thinking while everything is apart would be a good time to mod the tunnel for the Allison or would there be nothing to gain and should I keep with the 4l80e idea?

[Steve Chryssos]

The Allison is one big mother. Tallest transmission there is. Whatcha building?

[astroracer]

Like Steve said, Allisons are big. What year? Prior to '06 they were 5 speeds. I really don't know what you would gain by using one. Getting the trans to talk to your computer will probably be expensive also.

[dgrown]

my car is a 69 impala the hole reason i was considering it is my 03 Duramax is just about dead 362,000 plus miles and the trans is in good shape just kinda figured I've pushed that truck up to 600hp and the trans has always taken it and shifted nice that is why i was considering it and figured my car is big and heavy enough it might be worth it.

[astroracer]

If you have the trans and the electronics go for it. Sounds like another option. The gear ratios aren't that far off from the 4L80E so there shouldn't be any issues there.

[Steve Chryssos]

It's a cool trans for sure. Plan on raising the engine to compensate for the trans pan and, after that, study the impact on pinion angle before pulling the trigger. Could be you'll need a two piece driveshaft with a carrier bearing to maintain pinion angle. Allison converters are monsters as their designed for towing. Explore having a smaller dia. custom converter built. I might be able to help in that department.
Last but not least, if the standalone trans controller maintains all of the Allison's benefits including full engine braking, go for it.

Otherwise, keep in mind that the 4L80E will jump out of the box and install itself, comparatively speaking.