What are some good flow numbers for a fully ported PI head?

ADRENLN said:

you wont get anywhere near 370 rwhp na!!!!

the top , top na dogs get about 330rwhp.

you will every mod i have + instead of my cams youll need stage 2 or 3 na cams + youll need an aftermarket intake + under drive pullies + electric water pump. you might see 330rwhp if you do all this. if you do a built short block with high compression you might be able to see 350rwhp........all this should cost about a million dollars for 350 hp. spend your cash on a blower and youll be at 350 easy.

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I have talked with about 6-7 Mustang speciality shops around the country. They ALL say that most of the heads/cams, 1mm oversize valve 4.6 2 valve cars they dyno are around 350-375 RWHP depending on the heads and cams of course. 330 RWHP would be considered a relatively low number for a "properly" done heads/cams car. And yes, these are all stock bottom end cars.

Also if you do the math on a PI head that flows roughly 225-235 CFM peak, the basic mathematical formula (HP = CFM x 0.2575 x # cylinders) used by most engine builders dictates that a peak of 464 HP to the crank is possible with 225 peak CFM. Obviously that is pulling out all the stops.

The thing that lots of people, including yourself, don't realize is that there are lots of little "uncommon" tricks to making HP. Vacuum pumps, intake manifold runner length tuning, aggressive custom maps, custom grind camshafts, etc., etc.....the list goes on and on.

This motor in this car is definitely freakish. The 423 RWHP on a 125 shot, on a Mustang dyno no less, is nothing short of amazing. BTW, in case you were wondering, the jet sizes are 57 N20 jet, 31 fuel jet. That equates to roughly a 125 shot on a Ford 281" 2 valve SOHC. I am not sure how familiar you are with nitrous, but typically on these 4.6's, the "target" jetted HP is usually surpassed as evident in the common dyno numbers. Given this, I should be able to subtract roughly 125-135 RWHP to closely estimate the all motor RWHP. You do the math.

Honestly I didn't believe the previous owner when he told me the dyno results, until I drove over to Coastal Dyno and talked to Sam. He remembered the car, and remembered dyno tuning it.

Gearbanger 101 said:

I'd check out Fox Lake or Patriot Performance for some reasonably priced, high flow ported heads. They flow every bit as well as the others some have suggested and won't take 4-6 months to turn them around.

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Thanks for the advice. I have worked before with Patriot and they have always been well known in the LS1 community (yes I have an f-body ) to produce some very good bang for the buck heads. I will also give them a call and see what they have to say.

What are the average bone stock RWHP numbers on these motors with a 5 speed?

Adrenln, you are acorrect, CFM does not always equate to HP. There is a very fine line between velocity and flow. Too much flow and you can inhibit velocity. Consequently by working a head to only make good velocity can limit it's flow characteristics.