GT40 -vs- GT40x

[93 svt]

I know a lot of you know a great deal about mustangs and expecially cobras. So my question is...on my 93' how much of a difference in horse power and torque can I expect from GT40x heads over the stock gt40 heads? A friend is giving me his for my cobra cause he just got a set of AFR185. Thanks for your input.

 

[LEE93COBRA]

a lot. I would say at least 30hp more to the wheels depending on what cam you have

 

[19COBRA93]

Agreed. My buddy and I had similar turbocharged engines, and mine (93 cobra), all stock with an F cam, his was everything the same but with the X heads, boost to boost he made nearly 40 rwh more than me. Same compression, intake, cam, injectors, turbo, Trans, everything was the same between the cars but the heads.

Although, he did have a much shorter driveshaft as this was in a Factory 5 Cobra.

 

[93 svt]

Wow so a free set of gt40x will work good. by the way It has an e cam.

 

[golden_eye]

That's a good deal. Plus together they will be probably about 50 lbs lighter since they are aluminum.

 

[19COBRA93]

Yep, 25 lbs lighter per head than our cast iron GT40's. Plus you can get $300-400 out of your stock GT40's. Throw some ARP's and Felpro head gaskets on there with them and you're good to go.

 

[biminiLX]

If you're getting them free find a good local shop to do some porting for you, just my thought. Those heads can pick up with some minor work, especially on the exhaust.
Nice friend and nice upgrade, good luck.
-J

 

[FoxSnk]

Without changing anything else, I wouldn't expect more than 20-25rwhp difference. Still worth it, especially with a cam change (35-40rwhp).

 

[Big Ben]

Wow I had no idea the X heads were worth that much. So how much more over that would an AFR 165 be worth? How much cost difference typically?

I like the idea of having a GT40X head over an AFR, just seems more original with a Ford part on there for some reason.

 

[LEE93COBRA]

Wow I had no idea the X heads were worth that much. So how much more over that would an AFR 165 be worth? How much cost difference typically?

I like the idea of having a GT40X head over an AFR, just seems more original with a Ford part on there for some reason.

Here ya go Ben, Stock with a B cam vs a 165 head swap. Worth every penny to me

Blue lines are with AFR's
Green lines are with GT-40 irons.
Everything else was the same between combos

 

[fivestangs]

^^^^^^^^^^^^^^ IMHO, that's damn impressive for a bolt-on head

I finally got a chance to swap some AFR-185s onto my 388 stroker which had gt-40Ys(!) on it (long story), and it's like night and day...the car is down right scary now :rolling:

...and yeah, even the 185s are probably "too small"

 

[biminiLX]

Wow I had no idea the X heads were worth that much. So how much more over that would an AFR 165 be worth? How much cost difference typically?

I like the idea of having a GT40X head over an AFR, just seems more original with a Ford part on there for some reason.

I hear your point on Ford parts with a Cobra, but you actually race your car and you would be giving up significant power with a GT40x vs. AFR
Do you have stock pistons and unported intake?
-J

 

[mgerman93]

I ran the 64cc X heads out of the box on my cobra back in '98. Very good cylinder head, especially if they are free. I was able to run consistent low 12.20s @110+ with a 1.57 sixty foot. If I'd known then what I know now, that car would have run 11s without much trouble. The only knock against them is the cast iron guides. Ford should have given this head bronze guides...........

 

[19COBRA93]

The only knock against them is the cast iron guides. Ford should have given this head bronze guides...........

I'll second that. I know several people who have had trouble with those stupid guides.

 

[Red Turtle]

I don't have any dyno numbers, but my Irons back in the day were pretty stout. I had them ported, ran an E303, and had the upper portmatched/extrude honed and the car ran 107mph N/A (of course with the other basic bolt ons like full exhaust/3.55's).

 

[Big Ben]

I hear your point on Ford parts with a Cobra, but you actually race your car and you would be giving up significant power with a GT40x vs. AFR
Do you have stock pistons and unported intake?
-J

That's a very good point. Yes my valve covers have never been off!

 

[tt54l32v]

how many diff types of gt 40's are there. what comes on a 00 exploder im pretty sure there alu but not the x head am i right?

 

[LEE93COBRA]

Explorers do not come with aluminum heads. They are iron GT-40's that are similar to the 93 cobra heads. (explorer gt-40's have smaller valves)

GT-40 heads that I know about

GT-40 irons from Lightnings and 93-95 cobras
GT-40 irons from explorers
Aluminum versions are:
GT-40Y's
GT-40X's
GT-40Z's

 

[biminiLX]

Exploder = GT40-P
Needs different headers and I think spark plugs (or maybe its just the plug location).
Better than Cobra/Lightning GT40s.
-J

 

[19COBRA93]

The early 96 Exporer had a unique GT40 type head. It was sort of a hybrid GT40/GT40P head. They had the smaller "P" valves, and the smaller "P" combustion chambers, but the regular GT40 spark plug angles. There isn't a lot of info out there on these heads.