4T45E : Whats The Max HP it can handle.

[Garnetdawn]

Ive been wondering about this for awhile. But how much Horsepower can the 4t45E Trans handle before it fails?

It depends on how you drive it and if the programming logic has been adjusted.

[G.I.Ceo]

Originally Posted by Garnetdawn

Ive been wondering about this for awhile. But how much Horsepower can the 4t45E Trans handle before it fails?

Nobody has pushed one hard enough to see where they will break at. Speculation is 350hp is about tops but no one really knows. I'm turboed with 16 pounds of boost, ported head and intakes, and mines holding strong. The tune is a huge part of the reliability of it. Since the current tune we have slapped in mine it actually works better then it did new.

[Redog]

I'm on my 3rd transmission right now.

First one broke because I was launching the car way too hard at the track. I was stall launching at 2250 RPMs, about 1000 RPM higher than the stall on the convertor. I broke a piece of the case off and had a 2" by 6" hole/section in one of the axle shafts. Drove the car for a week after that until all the gear oil leaked out then burnt up the trans driving it to the shop. 65,000 miles on it

The second one was actually was the first one rebuilt/recased Could have been all the orginal clutchs reinstalled in a new case. In December 2012 the trans would slip going into 2nd and overdrive. Got upto 135,000 miles

This current transmission was a used auto parts buy. It was out of a 2003 Pontaic GAGT with only 21,000 miles on it. If you can't afford to go the GT40 transmission route, this is the next best thing with the 3.29 FDR vs the 3.05 in the Alero and GASE. Car now sits with 147,000 miles on it, but is no longer a daily driver.

It's not the HP that breaks things, it's the torque.

Also, pending on the year Alero you have, in 2004 they changed the transmission pump a bit. Rumored to need a different program in the PCM. I couldn't find any soild facts on this, so I just played it safe and went with the newest I could get with little known issues, the 2003. The Axle seals did change in 2001 to a smaller size, but even with that, it's all a straight bolt in and a slight change in the PCM which is no problem if you have HPTuners

[[ion] C2]

Long story short, gathered from around the internet by user experience on forums and specifications, the max output is only rated to somewhere around 210-220 ft-lb torque. Exceed that and it won't like it.

My 4T40E did not allow all my power to the wheels and had issues shifting and taking off in the end.

[kwhauck]

Originally Posted by G.I.Ceo

Nobody has pushed one hard enough to see where they will break at. Speculation is 350hp is about tops but no one really knows. I'm turboed with 16 pounds of boost, ported head and intakes, and mines holding strong. The tune is a huge part of the reliability of it. Since the current tune we have slapped in mine it actually works better then it did new.

Umm, yes they have, mine went through two trannies.

[G.I.Ceo]

Originally Posted by kwhauck

Umm, yes they have, mine went through two trannies.

How much torque and HP were you putting down? Ive been thinking of switching over to a 4T65E-HD. I figure while the tranny is holding there is no sense in swapping it quite yet.

[[ion] C2]

300+

[Garnetdawn]

Well it cant be 210-230 becuase stock rating is 210 Ft-lbs of torque usaully along with the engine they over engineer to handle about double before you need to replace shit

[Garnetdawn]

Any suggestions for a performance Sprag and roller clutch?

[MMGT1]

Put close to 400 through my 4T45E, took it like a champ.... 240,000kms as well. I would not suggest more than 250 without proper tuning, but set properly, they are a hell of a lot stronger than they are given credit for and Ive been saying that for years now....

[AleroB888]

Originally Posted by Garnetdawn

Well it cant be 210-230 becuase stock rating is 210 Ft-lbs of torque usaully along with the engine they over engineer to handle about double before you need to replace shit

My first (1999) 4T45E handled well over 210 -230 for many years, before it finally went. I did have it flushed out a couple times, though. That one must have been better than average, it shifted firmer than my most recent ones. I can't imagine any of these trans getting more abuse long term than that one did, except maybe Paul's.

The last run on this vid shows how firm the shifts were, with a switch to raise the line pressure :

http://www.youtube.com/watch?v=C0SbmN4-6Mw

[Garnetdawn]

Im just wondering next on my list is suspension im tired of 13 year old springs and struts

[jawa]

build it and test it
then you will have your answer

[Garnetdawn]

I have to agree with that