I put this in transmission section but my question about auto trans is directly related to my forced induction build. I have been running a T56 trans with my nitrous build and having fun but due to my new direction of build and an auto accident injury I am swapping to an auto.

I have researched more then I care to admit and still conflicted on what transmission would be all around best for my build. I am faced with these choices:

Powerglide
TH400
4L80

My formula is 70 percent street and 30 percent strip. I do not mind giving up some street comfort and insist on getting the car deep into the 8's (8.5-8.7). It's a forged 347, trick flow 215 heads, custom spec solid roller cam with supporting mods, LS6 intake, E85 with Lonnies double pumper kit, 10.5:1 compression, truck manifold front mount BW 480 Billet t4 turbo, treadstone intercooler, Eboost2 controller, LNC2000 launch control, moser 12 bolt, 27 or 28 inch tall hoosier QTP tires, complete tubular suspension, short arm, some weight reduction currently at 3320 before cage and turbo. I have yet to determine type of trans, converter and rear gear. I wan't to order my cam but can't until I determine the aforementioned. I still want to be able to drive the car with automatic functions and forward valve body on the freeway since I live 30 miles away from civilization. lol

It seems I discover pros and cons to every build option. I am undetermined if I need a trans brake yet. Will the experienced please help? ;-)

I am leaning toward 4L80 with a Yank 3800 but still unsure. Seems I can pick up quite a bit of et with a th400 or glide, I am on heavy side for a glide and am fearful of killing street driving ability

 

I think you are going to be shocked by how much you can actually "street" your car when you run an e85 turbo car with any size converter over 3000. Ask me how I know. lol

 

ok, how do you know? ;-)

 

I would suggest either a TH400 (less expensive but you give up OD and lockup) or a 4L80E.

Transbrake will be helpful with the turbo but optional.

 

Will I be able to utilize the overdrive with a 3600-3800 converter? Can I get a transbrake forward auto valve body? I do not want a manual valve body. How much et difference between the 4l80 and 400 at the track?

 

Yes, you can use OD with the converter stall being in that range.
We make a auto shift forward pattern transbrake for the 4L80E.
In our experience no difference in ET. We had one car pick up slightly with the 4L80E, probably due to a slightly better converter.