GT/CS Guy

Hey guys. I have a 2009 GT/CS. I currently have 3.73 gears, shorty headers, straight pipe cat-back exhaust and a 2.3 (11 psi) Whipple Supercharger. I'd like to add some FRPP CNC ported heads and change my shorties out to longtubes. With the added HP that those items are "supposed" to provide, it puts be right at the limit of powers/safety with the stock block/pistons/low end.

I'd like to get some inputs on whether you think this would be a good idea or what other mods you'd recommend if any. Should I change out the rods/pistons since the motor will basically be mostly apart? Any and all opinions are welcome. Thanks!

-Mike.

05YellowGT

If you already got 510 RWHP , then you're past what most consider safe. I've had between 430 RWHP and 460 RWHP on my car since it had 25k miles, it now has 100k and it is still going strong. I have a safe tune and the A/F is always around 11.2 - 11.4 at WOT. A lot depends on your tune, and how lucky you are

GT/CS Guy

Well, I talked to the Ford Racing developers personally and they said that when they were testing the 4.6, it was able to handle 660 at the flywheel before throwing rods/pistons. They said that roughly being around the 550 range is the safety limit, depending on how the car is tuned. These are why they sell two Whipple kits. One is for the automatic rated at 475rwhp. The manual version is rated at 550rwhp.

Fords4Ever

I thought the FRPP Whipple kit was 550 flywheel hp not rwhp. Otherwise wouldn't that be adding 300hp from just the canned supercharger kit?

2k7gtcs

I agree. They are flywheel hp rated NOT rwhp.

lexi2013

550 crank hp so minus 15-20 give or take and that should put you around 440ish rwhp if my math was correct.

muscledom

Don't waste money on heads. Get the stock ones worked.

retfr8flyr

You can't really safely make any more HP then you are now. Just start saving up for a forged shortblock, if you want more power. Don't be like so many and blow your stock setup and have to start from scratch, with a new block. The aluminum blocks are getting very scarce, as Ford doesn't make them anymore.


Earl

GT/CS Guy

Thanks guys. It appears I'll just have to live with what I have. And that's totally fine, I was just looking to get a little more. Yes, the numbers are rated for flywheel, not RWHP, but I was able to increase the stock blower PSI from 8 to 11 and with my other mods and a GREAT local dyno tech, I was able to get to 515rwhp. Now that's on a completely cold soaked engine and I only got those numbers once. All my other dyno runs averaged around 495, but that was when the motor for more hot soaked. I'll see if I can't make an appointment to run it again so I can post the sheet. Thanks again.