Moddedshelby

Does anyone know how much horsepower a 2007 mustang gt automatic can handle before needing to do major engine work?

antdog

I have heard and read that the magic number is 500 hp.

ETNOATS

Consenus on here is around 450 to the wheels. But depends on how hard you drive it.

Gtpony325

The most i have heard is 550 before critical failure. I would think safely for maybe everyday driving would be 400 maybe a bit more to the tires. I wouldnt push it too much harder than that.

5pointoh

450 RWHP seems like the popular number....can others verify as well?

450 RWHP = approximately 500 HP at the crank??

sound wave

i can't find any literature to back me up, but i heard 450/450 to the wheels. i was never sure if that is for manuals or autos. in either case, 450 to the wheels is more than 500 to the crank.

Jmeo

I have heard 450 is the number as well. I can tell you to figure out crank horse power you divide your RWHP by .85

For me I have 455 RWHP so the equation is 455/.85=535 at the crank.

slidejob

The auto won't take 500+ for long.

Shoot for 400 & you'll be safe.

Imatk

There is not literature to back any aftermarket claims.

Vendors will tell you that xxx rwhp is "perfectly safe" and then when you blow your motor will be just as happy to help you buy a new one from them.

No one knows how much a particular engine will take for sure... it's a guess... sometimes an educated one and sometimes people are blowing sunshine up your but.

450 rwhp is the consensus as a "safe" level, but there have been motors let go that were under that level.

Not all motors are the same.... not all drivers are the same, etc.

The stock engine was designed for 300 flywheel hp and anything out of that realm is a guess as to how "safe" it is.

Long explanation short... 450rwhp should be ok but you never know.

black sunshine

I think a good indication of what these motors can handle (at a minimum) is by looking at the 05-10 Roushcharged 4.6L. Stage 3 and 427R. These cars come with a supercharger on an all stock 4.6L and produce 435 fwhp and 400 fwtq. These cars come with a regular factory warrenty and are somewhat mass produced. I believe that there is no way Roush would have done this if it was unsafe for the engine or it couldn't handle it. That being said, at a minimum with the right tuning, I belive these cars can handle at least 435fwhp safely.

fdjizm

500 at the crank (450whp) is about where you want to draw the line.
I'm going to stick to around 430-440 when I put my procharger in, of course the majority of the expected life is in how good the tune is, I know of a few people putting 500 to the ground doing just fine. I wouldn't push that but it's not impossible.

Doogie

Don't forget the tune... a properly tuned car will drastically reduce the chances of failure with any power adder. But as with others, the common consensus is in the low to mid 400 range at the wheels to be safe. Mine ran 2 seasons with 420 at the wheels and now I am 450 as of last fall. I don't beat on mine, but am very comfortable at the current level.

Imatk

Yeah I'd agree with that, I'm sure Roush / Ford wouldn't warranty the motor if they thought it would pop in 3 yrs ... but remember you're talking about 350-360 RWHP which is far from the 450RWHP that's generally tossed around.

black sunshine

Yeah, I'm sure Roush isn't on the brink with 435 fwhp and 400 rwtq. They're probably well within the "safe" buffer. What that is......Only Ford and maybe Roush know for sure.

sound wave

i don't think the 400 ft/lbs torque is to the wheels.

black sunshine

That was a typo on my part......I was just waiting for somone to catch it and comment.......your the winner.

Ghost

If you're looking for manufacturer's claim this is straight from the Ford Racing Direct website:

Ford Racing's internal testing recommends that their upgraded aluminator forged internal short block assembly (M-6009-A463SC) be used when making over 600 HP. Otherwise, this top end power package will be fine for the stock short block in normally aspirated trim."

But hey, it's your money........

forensicsteve

You can do what I did

Ran 8-9 lbs of boost with stock motor...no worries. Then got a built 302 stroker, ran 22 lbs of boost for a while and blew that one up...lol. Since rebuilt the built motor stronger and looking for 25+ lbs of boost. Expect that to blow after a while. Tune is critical but how much stress is placed on car and how often, is also critical and not always disclosed.

The stresses placed on a motor during the dynotuning are not the same as those at the dragstrip. Lots of folk claim 500+ rwhp and not a problem, but do you know how that car is driven?

You go to LSU as in BR?

fdjizm

Very true LOL, I'm sure there are people with 500whp that one time on the dyno but never drag race their cars or get into boost once every 6 months lol

You can drive a supercharged engine and not go above 4 psi it's whole life if you wanted to. But that stuff is reserved for dyno queens

Imatk

This is a PERFECT post so much so that it should be a sticky!

There are so many guys that think if they get a motor built that their worries are over and they can drive the car forever with as much power as they want because it's the magic of a "built" motor.

SO then everyone want to get a "built" motor because those are great and the stock motors are crap compared to them.

Vendors LOVE this notion and will do nothing to dispel it.

A built motor, a stock motor, a motor with some jou jou witchcraft prayed over it... they ALL can fail.

It's all about how you drive it, how much power you're running through it, and if it's tuned properly or not.

And yeah a lot of guys claim 500rwhp and it's fine and then when you ask them for a dyno sheet they suddenly go silent.