This is topic GT40 vs GT40P Heads in forum Tech Talk at Northern California Ford Owners  .


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Posted by 94RedGT (Member # 171) on :
 
What is the difference between them exactly?

What kind of difference in power can I expect between the GT40/GT40P heads vs my stock heads?

How well would they work with the Edelbrock RPM Intake?
 
Posted by shade-tree (Member # 298) on :
 
little to no appreciable difference, probably advantage to the 'P' to the tune of 5 ish HP.

redesigned spark plug locations necessetating a different style of shorty header (or the same long tube as before)

better swirl #'s
 
Posted by nitrous_bob (Member # 77) on :
 
everyone says the "p" heads are better...but i have to disagree.
My buddy used a set of 40's off a cobra, just cleaned the exhaust up a bit and decked them to raise compression.
w/ those and a box stock GT-40 intake he dropped from 13.40's to 12.80's.
I've never seen a similar combo like his w/ p's even get into 12's. And you need the special headers.
But thats just one car......and 1 guys opinion.
 
Posted by 93PONY (Member # 60) on :
 
P's have smaller exhaust valves, yet flow is not compromised..... Smaller valves w/the same flow = faster velocity = more torque.
Problem is, both heads have sevearly choked up exhaust.
 
Posted by Glenn (Member # 520) on :
 
I hear the P's have a little more HP, this is from a guy who builds motor's using both heads. The same guy said, cost effective, you are better off saving a little extra to get alluminum heads, fact is heads are about $600 assembled, plus you have to buy the headers, which is another $250, that is $850, $150 more you got a set of Trick Flow Twisted wedge heads... my $.02
 
Posted by st5150 (Member # 51) on :
 
The P's have a smaller chamber so you get a bit higher of a compression ratio and like previosly said, the exhaust port flows the same as the regular GT40's, but with a smaller valve. The spark plug is also angled to face the chamber better for a more complete burn. I'd guess a 1MPH difference between the two heads. As for the intake, unless you have some heavy porting done, stick with the regular Edelbrock Performer intake. No need for the RPM version.
 




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