Stock Auto Tranny MAx Horsepower

[wide]

I just bought a 2000 GT Convertible last week.

What I would like to do is add a little more power to make up for the fact that I bought an Automatic. I was gonna start with an air intake and exhaust. I figure that should be good for the 25 horses I probably lost relative to the manual. My question is this though...

How much horsepower can I get my engine to produce with absolutely no problems from the stock automatic transmission. I have no desire (at the moment) to add more than 50 HP. Is this OK on the stock tranny?

Thanks

 

[speed545]

I just bought a 2000 GT Convertible last week.

What I would like to do is add a little more power to make up for the fact that I bought an Automatic. I was gonna start with an air intake and exhaust. I figure that should be good for the 25 horses I probably lost relative to the manual. My question is this though...

How much horsepower can I get my engine to produce with absolutely no problems from the stock automatic transmission. I have no desire (at the moment) to add more than 50 HP. Is this OK on the stock tranny?

Thanks

Welcome to the board
First mod to do to compensate your desavantage to the 5sp is 4.10 gears.
Beleive me it s working
As far as HP goes, 4R70W can take WAYYYYYYYY much than 50RWHP. Those tranny can probably handle, when taking care of, 400RWHP.

Dont forget a good tranny cooler also!!!!

Have fun

 

[wide]

Those tranny can probably handle, when taking care of, 400RWHP.

Dont forget a good tranny cooler also!!!!

Have fun

400 RWHP,, holy shi$, I find that a little hard to believe, but I hope it's true.

 

[speed545]

400 RWHP,, holy shi$, I find that a little hard to believe, but I hope it's true.

On MD forum, a guy manage to race a full season on a stock 4R70W with around 550RWHP before getting some problems. Another one is putting around 300 RWHP on also a stock 4R70W without anyproblems.
They are good tranny, just need to take care of it.

 

[CManT1914]

You shouldn't have any problems with the tranny, but first you should get some gears (maybe 4.10's) for sure. That will make a HUGE difference in the performance. You might do those and decide to leave well enough alone.

 

[bdcardinal]

you can leave the transmission stock internally, however adding an auxillary cooler will help a lot. also keep the fluid in there flushed and pink. change it evey year with a good synthetic Mercon V ATF. also make sure when you change the fluid to change the filter and to never do the flush type thing that dealers and quick lube places offer.

 

[Gearbanger 101]

Mehhh, some say that the 4R70W sucks in comparison to a 5-speed (usually 5-speed owners )....and in stock trim, I might tend to agree. But couple it with shift reprogramming, a stall converter and 4:10 gears and you'll be showing 5-speed guys your taillights and running more consistent times as speeds than them all day long.

 

[wide]

Mehhh, some say that the 4R70W sucks in comparison to a 5-speed (usually 5-speed owners )....and in stock trim, I might tend to agree. But couple it with shift reprogramming, a stall converter and 4:10 gears and you'll be showing 5-speed guys your taillights and running more consistent times as speeds than them all day long.

Sounds like a plan to me

 

[wide]

Anybody know what kind of 1/4 mile differences you get from switching gears only. on the auto

 

[CManT1914]

As long as you don't have traction problems already, then maybe .5 seconds.

 

[STNGLVR]

I HAVE A 99 GT AUTO W/80K MILES. I BOUGHT IT W/50K MILES AND I GUESS THE PREVIOUS OWNER BEAT ON THE CAR CAUSE THE WAY THE TRANNY SHIFTS SUCKS BIG TIME! ANY HELP TO IMPROVE?

 

[bdcardinal]

I HAVE A 99 GT AUTO W/80K MILES. I BOUGHT IT W/50K MILES AND I GUESS THE PREVIOUS OWNER BEAT ON THE CAR CAUSE THE WAY THE TRANNY SHIFTS SUCKS BIG TIME! ANY HELP TO IMPROVE?

first off try hitting the caps lock, we dont need to yell around here.

check the condition of the fluid, how does it look? is it brown and stinky, or pink? if its brown try changing it, dont go get a flush, drop the pan, change the filter, drain the torque converter, and refill with fresh Mercon V. this should help out a decent amount. just be aware that if the fluid is like black and it smells like a BBQ then you are looking at getting a trans rebuild. ive seen 4R70Ws go bad within 15k miles of hard driving.