What's a safe rpm to have a 2005 fx4 shift at in the tune? Stock I'd 5k right...can the trans and motor take more....5500...5750?

 

Your camshaft and heads are the primary dictators of the power band. No tune is going to move your peak horsepower rpm much over stock. At 5,500 and 5,750 you're just stressing the engine and transmission. 5,250 rpm is probably as high as you would want to see on a stock engine. I presume you're discussing the 5.4.

 

Yes the 5.4...and I should have said that I plan to drop in the frpp hot rod cam mainly for sound...but if it's still making power at 5k...I wanted to know what could I safely go to if the power was still climbing.

And for conversation sake...if the motor was built and had pnp heads too...what can a stock fx4 trans take rpm wise?

 

Both the HP and torque are dropping above 5,000 RPM. The torque converter starts to balloon above 5400 RPM (according to Troyer).

- Jack

 

The engine is good for 6k, but the stock tranny should not be run over 5400. You may balloon the torque converter.

 

Cool thats what I was looking for...so unless its something drastic over 5k at like 5250 I will just keep it to 5k. Tranny has 140k on it already....

 

with cams you might run lean in the upper RPMS if you're still using the stock 19#ers

 

The plan was stock injectors...upper rpm's being above 5k or under the stock shift point? I will have it dyno tuned once cams are in so I will keep an eye on the a/f

 

The dyno should also also pinpoint your peak rpm. If your power band moves up a few hundred rpm you might want to replace the torque converter anyway with a good aftermarket unit with a higher stall.

 

I'm sure the tranny will need some help sooner rather than later with 140k on it...I'm trying to let it ride like it is for now.

If the stock injectors run out up top do y'all know if 2006 mustang gt stock injectors would fit/work? I have some from when I put my whipple on it.