gt40 vs gt40p

1

1qwik90coupe

Forum Member
pros and cons whats better. gt40 or the gt40p. f303 cam explorer intake or get better.roller rockers.any input guys car also has 4.10 gears
 
i would run reg gt40, then you wont have to swap the headers, i think you will make the same amount of power, the gt40p is a fast burn head( spark plug angle is diff)
 
Power wise pretty close to the same. You'll need less total timing w/ the P's because of the better chamber (mine made peak hp at 29 total). The P50 FRPP shorties fit, MAC and BBK longtubes too. Either will work well w/ the F303.

Explorer intake is about on par w/ the Cobra intake from FRPP.
 
GT40's have huge chambers...like 65.5 cc where the P heads are 59. You will make more compression with the P's unless you cut the GT40s. I used to run NMRA factory stock and made more power with the P's than the GT40's with them both at 58cc chambers.
 
motorcitymustang said:
Didn't they have some factory versions w/ smaller chambers ala the '93 Cobra?
Click to expand...

The Cobra had a GT40 motor in it, same bottom end as a regular Mustang. All though, it had GT40 heads, and the cast GT40 intake manifold. There are some other differences but, those are the biggest ones.
 
I ran the P heads, and loved them. bbk shorties will work, thats what I ran and those practically grow on trees. a friend of mine went 12.33 @ 117 with p heads and an x cam 4.10 gear and a good tire in a 5 speed car. hes a hell of a driver though.
 
the p head actually comes with smaller valves as well, over all your dealing with a head that was engineered in the late 90s as opposed to the late 80s so it has to be better right lol
 
^ I remember talking to you back when I was building my 84, didnt you have a website and everything on these heads ?
 
Yep. Working on trying to get it posted again as a question still occasionally rolls in and it's been 7-8 years since I did anything w/ the P heads (switched to Pro Topline 180s before I sold the car).

Would have loved to try the P head combo I had w/ a sticky tire behind it.
 
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