Has anyone used GT40 and nothing else?

bennylava · Mar 15, 2023

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!

white95 · Mar 15, 2023

You'd see *some* gain but still would be limited by the stock cam and intake. You’d benefit from a Cobra (or Explorer) intake with the GT40 heads. I don’t have direct experience with this combo but I made 243 with E7 heads, E303 cam and an Explorer intake.

RAU03MACH · Mar 15, 2023

94-95 already have gt 40 - p cast iron heads from ford

RAU03MACH · Mar 15, 2023

your looking for the 3 or a 4 bar head i wanna say
all cast iron heads 94 95 are baised on gt40

joemomma · Mar 16, 2023

GT40 = 3 bar
GT40p = 4 bar

To the OP - if you're going to go down to the heads, you might as well do the intake while you're there, and if you're going that far, you might has well do a cam and new timing components. I've got an Explorer intake that's been sitting on my garage shelf for almost 2 years waiting for me to get some heads and a cam together. I'm only going to do it once.

EDIT to add: "stock" GT40s (or Ps for that matter) won't let you run much of a cam without new valve springs.

bennylava · Mar 16, 2023

RAU03MACH said:
your looking for the 3 or a 4 bar head i wanna say
all cast iron heads 94 95 are baised on gt40

The GT cars had a different head, the E7. Cobras got the GT40

RAU03MACH · Mar 16, 2023

well i have a slew of them how many do you want .cant get rid of them fast enough
nobody uses them there just a plain gt 40head cast iron head

RAU03MACH · Mar 16, 2023

i have done many head swaps from cast to aluminum or 4bar 3bar
so i get stuck with them

joemomma · Mar 16, 2023

I might be interested in a set of 3 bar if you've got some laying around lol. Let me ask around and see what it would cost to get them refreshed.

ttocs · Mar 16, 2023

I have a lower intake in southern indiana if someone has the upper

bennylava · Mar 16, 2023

ttocs said:
I have a lower intake in southern indiana if someone has the upper

I'd buy that, but then I'll end up with two of them when I have to buy the upper and lower just to get the upper to go with it.

RAU03MACH said:
well i have a slew of them how many do you want .cant get rid of them fast enough
nobody uses them there just a plain gt 40head cast iron head

I'd buy a set of 3 bar GT40 heads from you, if I were in NM. But I'm sure shipping to TX would be more than the price of just going to a local junkyard and getting some.

joemomma · Mar 16, 2023

bennylava said:
I'd buy that, but then I'll end up with two of them when I have to buy the upper and lower just to get the upper to go with it.

I'd buy a set of 3 bar GT40 heads from you, if I were in NM. But I'm sure shipping to TX would be more than the price of just going to a local junkyard and getting some.

You can typically find just the upper or lower on eBay. I bought mine separate.

RAU03MACH · Mar 16, 2023

Let me refraze i get stuck with the ones nobody wants
I do not have 3or4 bar just the gt40p

Musturd · Mar 16, 2023

RAU03MACH said:
Let me refraze i get stuck with the ones nobody wants
I do not have 3or4 bar just the gt40p

Gt40p heads are 4 bar heads so you only have E7 heads

RAU03MACH · Mar 17, 2023

the ones i have that came off 93 94 95 gt 50.are not 3 or 4 bar and they are original heads that i have removed to replace with aluminum or better
if you need pics ill send if you want a set you pay the shipping ill send to you
it will get them out of my hair and yes E7 WITH P STAMP NOT WORTH A CRAP

bennylava · Mar 17, 2023

If someone didn't mind doing a whole lot of porting and polishing, maybe the E7 heads could match the GT40 heads. For 12 hours of work.

My next question would be:

What if you just did the GT40 heads, and the intake? But you kept the stock 94 GT cam. You could save a lot of money that way, because the cam is where these cars freak out without a tune. You must get a tune if you use a different cam.

But you could just bolt on the GT40 heads and intake, and not need a tune.

joemomma · Mar 17, 2023

If you had the tools/knowledge, you could certainly port the E7s and pick up some. How much? Dunno. Worth it? Debatable. Depends on how you value your time.

You could certainly do the intake and heads alone, and pick up a little, maybe 30whp?

RAU03MACH · Mar 17, 2023

It will cost about the same porting the heads
And its time consuming
Aluminum heads or a set that has been done is faster
Just a swipe of a card

ttocs · Mar 17, 2023

I thought the difference from the cobra to the GT was only 15 hp? So take the cam out of the equation and I can say it isn't worth the time for me to do it, with the cam I would still need a 12 pack to make it acceptable.

bennylava · Mar 19, 2023

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.