GT-40 heads HP increase...

MikeR351w · Nov 27, 2008

Hello,

I have a 93 LX 5.0 with a Edlebrock Perf. RPM II intake, a mild cam, gutted exhaust (H-pipe) and underdrive pulleys. Does anyone have a clue as to how much HP switching over to GT-40 heads would give me? I currently have the stock heads. Just curious as I have founds some for sale for cheap... THANKS!!!

5.0Droptop · Nov 27, 2008

deff worth the swap imo.

85_SS_302_Coupe · Nov 27, 2008

Well, weren't the '95 Cobras rated at something like 245-265hp or something like that? You should pick up at least 30hp i would guess.

GTOreturns · Nov 27, 2008

85_SS_302_Coupe said:
Well, weren't the '95 Cobras rated at something like 245-265hp or something like that? You should pick up at least 30hp i would guess.

Mmmm, I would say higher. Thumper heads (worked e-7's) are good for 40.

85_SS_302_Coupe · Nov 27, 2008

GTOreturns said:
Mmmm, I would say higher. Thumper heads (worked e-7's) are good for 40.

You mean the Cobras are higher rated or the gains are higher? How do Thumper's heads compare to GT40s? I'd assume they flow better but i don't know much about his heads. I know the '93 Cobra was rated at 245hp and most will say they were very under rated, and that the ECU/cam they used were junk and just switching back to the GT style computer will net you some gains. So, that's 20hp just over the highest rated GT, so if they're under rated i wouldn't be surprised if it's 30-40.

Well according to The Mustang Source.com (first site i hit after searching), the '95 was rated at 240hp. That definitely seems highly under rated to me...i know the GT40s pick up more than 15hp over the E7s.

TheMustangSource.com | Timeline: 1995 Mustang

cenok is family · Nov 27, 2008

thumpers flow better than any untouched gt40 heads, including the x heads. I went from 228 to 256 swapping from stock heads and cam to thumpers and an afm cam, but my a/f is out of whack. I think 40rwhp is about right on for power increase from thumpers.

which set of gt40's are you looking at?

old_blue · Nov 27, 2008

have thumper port ur gt40s

cenok is family · Nov 27, 2008

old_blue said:
have thumper port ur gt40s

+1

JohnnyGMachine · Nov 27, 2008

I bought a crate 302 from Downs Ford a few years ago that was producing 320 hp. at the crank. Stock 93-95 Cobra shortblock (stock cobra cam), GT40X heads, 1.7 rockers, Edelbrock Performer RPM intake, Holley 650, and longtube headers. Not bad for off the shelf parts and a stock shortblock. Currently I just ditched the GT40Xs for a set of AFRs, Lunati cam, and a Weiand Stealth Intake manifold. With some other mods such as a Canton deep sump pan w/scraper, electric water pump, and manual steering rack - should pick up some more power! I still have the GT40X heads and plan on reworkin' those and puttin' them on my daily driven 88 GT.

MikeR351w · Nov 28, 2008

Thanks for all the responses! I can buy them for $125. The only problem is they have bent intake valves, so I would have to buy new valves and get them installed. Anyone know how much this costs???

Would this make me have to buy new pushrods, lifters, etc??? Thanks...

:SNSign:

85_SS_302_Coupe · Nov 28, 2008

MikeR351w said:
Thanks for all the responses! I can buy them for $125. The only problem is they have bent intake valves, so I would have to buy new valves and get them installed. Anyone know how much this costs???

Would this make me have to buy new pushrods, lifters, etc??? Thanks...

:SNSign:

PASS on the bent valves.

I put all new stainless valves in my C9's, but i wouldn't have bothered if they weren't ported to the extent that they are. I've got $450 into the valves and valve job alone and i got a killer deal on the valves...they're not worth that kind of cash.

hollywoodstang · Nov 28, 2008

cenok is family said:
+1

thumpers will want around 700-800 for this job. I was thinking about doing this. But he is too expensive. I had set of gt-40 heads too and i was going to send it to him. If he supply the heads and ported and finished it, "YES" i will gladly pay 700 for the set of heads but this was not the case.

you are better off buying thumper ported E-7's directly from him. that would be the true budget heads.

I ended up selling the gt-40's and got edelbrock aluminum for $700/pr. I got lucky but deals are out there.

good luck

GT-40 heads HP increase...

MikeR351w

5.0Droptop

...all those nights we shared, and you're a dude??

85_SS_302_Coupe

it sucks (I know) to be on the receiving end

GTOreturns

Well-Known Member

85_SS_302_Coupe

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cenok is family

old_blue

cenok is family

JohnnyGMachine

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MikeR351w

85_SS_302_Coupe

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