481 Hp 5.7 Hemi

[phunter1]

In the last few issues of Hot Rod, they have been working with the 5.7 hemi crate motor, which is identical to our engines except for the fuel system, which is either a carb or throttle body EFI. Thsi is becasue of the need to put the thing in older cars. Anyway, in the October issue, they changed the cam to a Competition Cams XFI273. While much stronger than the stock cam, it is far from a race cam. Anyway, Hot Rod could not find a way to over come the 5700 rpm limit of the Mopar PCM, so the used a Ford PCM on the hemi. The net result was 481 hp @ 6500 rpm and 415 ft/lb @ 5000 rpm. This was on a dyno running open headers.
Interestingly, the were able to get 401 hp out of a bone stock 5.7 hemi, by changing to the Ford PCM and reving the engine to 6000 rpm., again on a dyno with headers.
They tried the 6.1 SRT8 manifold on the engine, but actually produced less power due to the port size mismatch. Future tests will use this manifold with some port matching work to see if it will produce more power. Overall, it looks like there is a lot more power to be had from the 5.7 Hemi, once the after market figures out how to deal with the PCM


Phil

[vvv90]

Something seems fishy here.....

I'm not saying BS but something seems left out.

JUST a cam swap with stock heads, intake, and open headers makes 481HP?

Well then the cats and mufflers run on the JohnHennesey SRT-8 with their top end package must be robbing LOTS of power because they're output in HP is about the same.....That's WITH cam, head work, SRT-8 Manifold, etc...

[Meister]

Originally Posted by vvv90

...JUST a cam swap with stock heads, intake, and open headers makes 481HP?...

Don't forget the Ford PCM, vvv90--that appears to have removed a primary obstacke to higher power output.

But still....

[JP300c]

maybe this is an ignorant question (i havent seen the answer yet) if that 481hp is unlocked...how much will the C's tranny and rear end hold?

[5point7]

The only thing fishy vvv is that your most likely comparing FLYWHEEL HP ratings from the magazine article (motor is on a stand with open headers, to Rear Wheel HP numbers that Hennesey puts out.

Doesn't sound fishy to me at all. I've read in quite a few publications that the new 5.7 is the "small block chevy" motor of the new century.
I think you will see some insane power numbers from it once the code is unlocked.

[phunter1]

Hi,

This is an engine running on a dyno, through open headers. There is no exhaust system, drive train, etc. Clearly, we are talking flywheel horespower.

[Model 57]

Sounds like some fun times ahead for us to me. Unlocking some serious horsepower sounds like what we have been looking for.

[Northern Rider]

Great times ahead, indeed. The 5.7 is quite "detuned" in its present form.

Lots of potential left in this strong, rugged design, IMO.

[phunter1]

As I said earlier, the stock motor made 401 HP, with no other changes than the Ford PCM, which allowed the motor to rev to 6000 rpm. For baseline purposes, the stock out of the box motor produced 376 HP at 5700 rpm. Again, this is on a Dyno, through open headers, so 340 HP installed in the car with an exhaust system is probably pretty accurate.
At any rate, it looks like there is a lot of potential in the 5.7, once the tuners figure out how to get past the 5700 rpm limit.

Phil

[mvpatriot]

::drooling::