head delema

[Kelly]

im not sure which way i wanna go here,im trying to decide whether i should go with the gt40 or the gt40p heads,i can get both but im hearing mixed results about both and have no idea which one is better or why.any help would be great.

[Mark302]

I can port some stock ones for you. GT40P's if you want to go fast and reg. GT40's if you want to get beat by the guys with the GT40P's.

[Kelly]

I can port some stock ones for you. GT40P's if you want to go fast and reg. GT40's if you want to get beat by the guys with the GT40P's.


very funny mark

[BP Convt]

I am doing up a set of GT-40's (non-P). There should be a nice gain just from bowl blending by looking at the intake and exhaust ports. I don't think your going to find any significant differences between the two. Make sure your current headers will work if you get the P's.

[Mark302]

Either set are better than stock by quite a bit. GT40P's have smaller exhaust valves but the rotated spark plugs more than makes up for it.

[Kelly]

i have heard the p's flow better and are a higher comp...is this true?

[BBATCO1]

Mark has the fastest car in this thread take his advice... :shifter:

[Mark302]

Mark has the fastest car in this thread take his advice... :shifter:

Not any more... :D


GT40p's flow 196@.500 Intake 139@.500 exhaust

GT40's Flow 192@.520 Intake 128@.500 exhaust

GT40P are 59cc combustion chambers making comp. ratio 9.5 to 1

GT40's are 65cc combustion chambers making comp. ratio 8.8 to 1

[Kelly]

wow that is a differance

[1slo5.0]

E7's flow 154@.500 Intake 107@.500 exhaust


Big difference!

[BP Convt]

Whichever set you go with, I'd recommend doing some work to each. GT-40's need to milled to raise the compression in a n/a engine. Also, lightly porting yields better flow and should not loose torque since they have small cc runners.

P's should also be ported and could probably benefit from a larger exhaust valve.

I do hate pedestal mount rockers when it comes to running higher spring pressures and shifting over 6,000 RPM's. I'm seriously thinking about having my GT-40's converted to stud mount rockers.

Also, the valve guide boss needs to be machined if you want a good dual spring setup.

Either version of the GT-40 head need work in my opinion. On the plus side, they can be usually found cheap. And when finished, these heads should be cheaper overall than a comparable set of aluminum heads.

Or, you could just leave them stock and they'll still outperform E7's. If you leave them stock, then I myself would lean towards the P's since the exhaust port is a better flowing design and yields a higher compression.

[4 nomor]

I was looking for a set of used gt-40's when I threw my motor together. I found a deal on a set of P's and have been more then happy with the results.. Whichever you choose, you will be light years better than the stock E7's..

[Mark302]

Is the 12.66 with the P's?

[Kelly]

thats really impressive numbers

[4 nomor]

Yeah, the 12.66 is with stock port P's. The only thing I upgraded where the springs... Next year I am shooting for a low 12 with the stock ports...It sure will be fun trying to get there!!...Oh BTW this is my street car in the summer, its not a drag only car...

[Kelly]

well i got my heads and a bunch of other things so tuesday i will be picking them up.

[Kool Rock Steady]

I heard about the heads Kelly. Good choice. Are you buying the intake also?

[4 nomor]

Cool, good to hear, what did you wind up getting??

[Kelly]

ya im getting the intake and fuel system also.should be a good setup.ill let ya know the specs after i get everything.

[scooter]

cool is the car going to be making some good power this year?
oh by the way i called you at work today but some one had the day off
scott

[fivonut]

Do P's require different headers or do stockers work?? Mark one of these days I'm gonna pick your brain on just how much I can mod a SD car.

[Kelly]

the motor is togeather...i just need to get my tranny rebuild and it will be back and ready to roar.

[Nick 1]

Congrats Kelly. Going with a 5 speed trans ??????

[Kelly]

damn skippy i am.

[clayton bigsby]

you'll never look back. congrats

[Nick 1]

Do P's require different headers or do stockers work?? Mark one of these days I'm gonna pick your brain on just how much I can mod a SD car.

How fast do you want to go ??????