No i think you will still be more than fine at 2500, shouldn't make too much heat and if you have a strong rad or after market trans cooler you will be fine. I would strongly suggest getting a 4 speed over a 3 speed, you really want that overdrive.

 

I would really like to order a 4 speed. The transmission builder (recommended by my engine builder) told me that in his opinion a Th400 has far better choice because far more high performance parts to deal with the large power of this 572. I also know that you are happy with your 4 speed. So I am a bit confused here which way to go.


With a 3.73 rear I would be doing approx. 2000 rpm on the 3rd gear at 70Kph. I would have 500 rpm less than the stall speed.


With a 3.55 rear I would be doing approx. 1980 rpm on the 3rd gear at 70Kph. I would have 600 rpm less than the stall speed.


I rather go for the 3.73 and TH400. If my calculations are correct, the engine will be happy with this ratio. At 6000 rpm (if I ever will reach this in Malta) it would be 125 MPH with 3.73.


What is your max speed you did? Have you checked your speed at 6000 rpm in 3rd gear and 4th gear?

 

so they can put an extra gear in one of those ,i think if i could have an extra gear in th350 would be nice ,,though i do got to say haveing it out on the highway a few times 3 gears sounds great , 3rd gear 100mph this was aprox 2000 rpm an 3,23 gears gu4 is how i found that in glove box i think puting the new 406 with the 99.000 mile tranny .slowly it does not like the way a high rmp shift from 2 to 3 ,it may be its age ,at the right it shifts perfect ,to much i feel it ,i am going to need to upgrade my rearend,sounds like your putting together a good match ,i got to say that car is going to scare you the first few times you drive it ,if you hit the gas ,an put a big smile on your face too ,i am very impressed with the power ,though i know this is show car ,if you got any need for speed it will come out ,i found a desent hard break in not to hard for 200 miles was just fine ,sorry if i am getting to far ahead,mine is max 5500 rpms

 

As strong as the TH350 can be built, I wouldn't choose that trans behind a big BBC. I had a well built TH350 behind my 427 that held up many years, and was still great when I sold it. But a 502, or larger BBC is a lot more HP and torque.

 

I think that is why he recommended the TH400 other than other transmissions.

 

As far as torque handling, the 4L80E is the 4 speed version of a TH400.

 

Yes I know. I do not know why he told me that. Is there any specific reason? I do not know..

 

Maybe because it's easier to slap in a 400 as opposed to what it takes to get a 4L80 to work.

 

I don't know how fast I have gone as I still need to buy a speedometer cable extension and I haven't hooked my tach up either. I would guess third gear pinned would be 150ish? Total guess though. What I can tell you is what I have said before. I couldn't imagine having a three speed again, on the highway I wish I had another overdrive gear. My 4L80 literally bolted right up using a different crossmember. My shifter bolted right up and I still haven't hooked up my speedo but the tail shaft on my trans accepts the old school cable. I have no electronics to speak of, and with the manual valve body there is no kickdown cable either. My trans is supposed to be able to handle 1200hp, whether it does or not I have no idea. I know you live on an island so I don't know how much open road you have, here I have thousands of kms of highways, I am almost tempted to install a gear vendors overdrive to get lower highway gearing. I would really, really suggest going 4 speed, I had a three speed on my last setup and highway driving gets treat old real quick. Oh yeah, if I didn't have and overdrive gear I literally bet if get less than 100km to a tank of fuel.

 

so the th 400 can be built with over drive ,like you i would like it on the hightway or raceing .but otherwise i tyed it again with gps 125mph 3rd at 2700 rmps an 90 in 2nd gear was about 2700 rmp ,it just bumps up to the stall speed ,for now i wont go faster then that ,,i dont want to dump that high miles 10 bolt yet ,other wise i love it ,get there pretty fast ,faster then it used to with stock lt1,now that i have 99 3800 i notice how 4th is nice when over 65 ,an the 95 would be great to have 4th at about 80 to 90 in actuality about 100 or more ,i need to be careful seen a state cop right after i slowed down he gave me a wierd look ,now that i know it can go fast ,i am good an knowing i got to 5500 rmps about half throttle ,the car could top at 180mph mabey more ,but i am not into redline since the burnout that blew a gasket ,,i know the guys with 500hp engines can go over 200mph an so with 413 rated hp low ,with high 458tlbs ,my love for speed ,fades a bit an ofcource iwas not dirveing it like iwas at the race track .just geting in the fast lane going wfrom there so the rpms in first ,were not seen