The stock 4L70 finally gave out after years of abuse. The transmission will be upgraded to a 4L80 with billet internals. A PI 3800 stall will be added. The flywheel had a small crack, so it will be replaced with a Circle D flexplate.
You should expect to loose power and response going from the 4l60e to the 4l80e transmission. Much stronger transmission but not nearly as efficient. I have been told to expect 2-3 mpg loss due to the transmission. However if you are going to a bigger engine or adding significant power it is hard to beat a 4l80e.
The engine is a 408 but, plans are to add a turbo later on. The 4L80 is suppose to handle 1000 HP but, I would like to be around 800 to the wheels. My gears are 4.56 so that will help with the 1st gear of the 4L80.
Lol I've been running the 408 for about 3 years already I think. But I'll keep posting information as I continue upgrading slowly. The original 4L70 handled a good beating and I was surprised it lastes this long.
It made 449 HP and 436 TQ on the dyno. This is using the stock L92 heads and intake. Stock fuel injectors and fuel pump. So there's plenty of room for improvement.
Now you have to figure out how to control it, I can program the ECM on my Gen 2 to do it. Your Gen 1 will be a little harder. What's the compression ratio on yours hopefully it's under 10 to 1 limit it to 5 PSI if it's not.
Wow. Now I have to imagine it with intake, injectors and boost. Literally a rocket haha. Do you have a video of this beast running the way it currently is set up?