4T40/45 tranny limits

[AJ03GA]

does anyone know just how much increase in horsepower the 4T40/45 transmission in my grand am will take. i've only heard about 120 hp. if that number is the safe limit that would keep me from my 300 hp goal. and i'm really hoping not to have to do a swap. anything is more than i know

[TurboGTU]

Well they've been behind the 3100 and 3400 and they are not 120hp. I'd say 260-300 at most.

From what I've heard the GM trans family works something like this...DONT quote me on it though...im still skeptical.....


Last two digits are the MAX torque rating times 10 for ONE second before trans failier..IE...4t40 40= 400lbs 4t45 45=450lbs 4t60 60=600lbs ect..

[geldartb]

http://en.wikipedia.org/wiki/GM_4T45-E_transmission

Engine range: 3.0L - 3.4L
Maximum engine torque: 205 lb-ft (278 Nm)
Maximum gearbox torque: 325 lb-ft (440 Nm)

http://www.media.gm.com/us/powertrain/en/product_services/Spec%20Sheets/Transmissions/2006%20Automatics/2006%20Hydra-Matic%204T45%20(MN5).pdf

[sharkey]

Well they've been behind the 3100 and 3400 and they are not 120hp. I'd say 260-300 at most.

From what I've heard the GM trans family works something like this...DONT quote me on it though...im still skeptical.....


Last two digits are the MAX torque rating times 10 for ONE second before trans failier..IE...4t40 40= 400lbs 4t45 45=450lbs 4t60 60=600lbs ect..

ive never heard that before. by that theory a 4l80e would only hold 800lb/ft for 1 second, when there are tons of people running more torque than that and having it survive.

[TurboGTU]

Yea. Thats why im skeptical. I've read it from a Grass roots website that a so called GM trans tech said. I do still look at the GM specs like the ones posted above. But its funny though since it also depends on how heavy a vehicle is. Theres some powerglides that handle 700hp, 600lbs all day on a 2500lb car but last one run on a 3500lb car. It all depends.