hey guys, my cousin has a brand new 700r4 that is dad is going to let him use. he is courious as to how much power that tranny will hold. he has the mods listed below in his car, and has a 700r4 now, but wants to how how much a brand new one---or any 700r4 will hold for that matter. i think that hes safe for a while being that the car already runs 13.75@103mph.
what do you guys think---safe for a while yet? is about 400hp a good high range for the tranny?

 

From what I understand, there's several factors - the year is especially important as the later models are much stronger. I'm cursed with having an '82 model (first year) that dies all the time.

Also, I was recently told that the torque converter clutch plays a big part in the failures. Locking one up too soon can cause it to fail.

The biggest problem I'm seeing in mine is the 3-4 clutch failure, and now it's even failed in 2nd gear.

A properly built one should be able to handle 400hp with no problem, but you've got an "unknown" transmission.