Has anyone used GT40 and nothing else?

joemomma

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Cobras (94 and 95) were rated at 240HP, versus 215HP for the GT. Seems like a lot of parts (heads, cam, intake, roller rockers) for 25HP. Perhaps the Cobra was underrated?

I would think GT40 heads, intake, roller rockers, and your cam of choice would get you the 30-50 HP most people seem to think it will. A good (aluminum) H/C/I setup will get you pretty close to 300 wheel. But that is quite a bit more expensive than slapping some GT40s on there. The heads are the big player here.

EDIT: TF sells a 432HP (crank) advertised top end kit. It's heads, cam, push rods, and roller rockers with gaskets and timing set. But, they are the badass 11R heads. That number is on an engine dyno, so real world would be slightly less, but that's still pretty close to 350 wheel.
 
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bennylava

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I think that's about all you can do before you tear a 302 block in half anyway. What was it... 450 hp and they're done. Unless you get some DSS block or some other expensive stuff.
 

07GtS197

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500 is the number but it’s arbitrary.

There was a discussion recently on the corral about Chinese aluminum heads and someone posted a set that I think summit sells under their name that’s a copy of trickflows or afrs. I don’t know what your budget is but a set of those with an intake would make for a nice gain without being too expensive. But then you’d need a tune too so there’s that.
 

joemomma

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500 is typically the number that's thrown out for block safety, but I think it's more about RPM in that range than anything. As long as you aren't spinning it to the moon, 500-ish should be safe, assuming a good tune.
 

302hobronco

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Thumperoforange Park does/ did great porting of E7 heads. I had him do a set for me many years ago. But I think he just makes them flow a little bit better than gt40 heads.
I have a 94 gt that was completely stock. I added gt40p heads that were milled .040 and had "alexs" springs put on them. A ported lower explorer intake and upper intake and the explorer 65mm tb. I put a mild comp cam in at the same time. Let me tell you it was a completely different animal after all that. Gobs more power.
 

Rod

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I wanted to stop by and ask if anyone here has just swapped GT40 heads onto a 94-95 GT, but did nothing else. So keeping the stock intake, and cam. What happens then? They say the GT40 heads are worth around 40 hp. But to get that, do you have to change the cam and intake too? What would happen if you only swapped the GT40 heads and did nothing else? Thanks!
Check out this guy - https://www.youtube.com/@richardholdener1727 . He does a lot of SBF stuff and has actually done some stuff specifically on the GT40/P/X stuff. He says GT40/P heads + GT40/Explorer intake should get you about 30-40HP over stock with stock cam. If you change your cam, and if you are that deep into the engine you should, for a better one the gains are better.
 

lutter94

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Not sure, google says the GT40 heads are worth 30-50 hp. What was the power difference between the Ford explorer engine, to the Mustang GT engine? It seems unlikely they made different heads and different intake to get 15hp. But maybe they knew it was good for a lot more if they wanted it, so they went ahead and made em? Who knows

Maybe you get 50 hp with Gt40 heads, explorer intake, and the biggest cam that matches those.
The explorers had a different power curve, you can give up peak numbers at the top to gain a lot of area under the curve further down the engine speed curve.....
 

302hobronco

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If your going to change the cam make sure you keep the LSA at or above 114. The 94-95 computers don't like tight LSA. I ran the comp cam nx264hr cam in my 94 with the gt40 top end. It was a great daily driver cam.
 

joemomma

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If your going to change the cam make sure you keep the LSA at or above 114. The 94-95 computers don't like tight LSA. I ran the comp cam nx264hr cam in my 94 with the gt40 top end. It was a great daily driver cam.
You could remedy this (and run your cam of choice) with a proper tune, correct?
 

302hobronco

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You could remedy this (and run your cam of choice) with a proper tune, correct?
Yes if the tuner can program for your cam. I have a bama chip with 4 programs in my car. My cam is 224int 234exh @.050 with a lsa of 112. It runs OK. But I desperately need to upgrade to some other stand alone system.
 

302hobronco

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I feel they are decent for mild bolt on improvements. But for my 331 it needs more tuning attention than what they can provide through the stock ecu.
 

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