gt 40 heads?

RideThePONYgt · Aug 5, 2009

ok so i know theres gt 40, gt 40p, and i feel like im forgeting something but anyway how good are these over stock 5.0 heads? i dont really know much about them so some inset would be greatly appreciated. thanks guys

Crone · Aug 6, 2009

From what I've read ( I don't really have much expeirence so don't depend on just me lol) They are decent if ported. I think the gt40p heads have larger valves, but they require special headers because of the spark plug angles. Some of the other manufacturers heads are better though, I have heard alot of good things about trick flow for the price. It depends what you are looking for really. But ported they are better then the stock e7's. It depends on what you want to spend. :dontknow:

LAFENATU · Aug 6, 2009

I have had 2 sets on 2 previous cars. Stock they are worth roughly another 25 HP over E7's. GT40s and GT40P's both have a 1.84 intake valve, the GT40 has a 1.54 Exhaust valve vs the P's that have a 1.46 valve.

The power diff in the 2 is negligable.

Ryno8705 · Aug 6, 2009

LAFENATU is right on.

GT40 = 96-97.5 Explorer is the same as the Cobra just not milled as much and the Explorers do NOT have stock roller rockers. So, the Explorer heads have a larger combustion chamber and less compression--easy fix=get them milled down.

GT40P = 97.5-01 Smaller combustion chamber, different angle spark plug (needs special headers, or some LTs fit, some have gotten by with special spark plug boots), the intake valve IIRC is just slightly larger than the GT40s, the exhaust valve is smaller (than GT40); but are supposed to flow better than GT40s.

GT40s vs E7TEs on a stock HO motor is probably good for 20-25 horse easy. That's mainly because the bottle neck on the HO motor isn't the heads, it's the lower intake-specifically runners 1 and 5. The heads are a bottle neck, but on the stock setup they are not the largest bottle neck.

GT40s vs E7TEs, if you have a cam and intake, GT40s could gain you 30+ horse. That's ball-park, everyone's setup will be different. But, as far as best bang for the buck, GT40s/GT40Ps will be hard to beat.

I picked up my GT40s for $80 at the local pull-your-part. An hour and a half of work, I had GT40s, 65mm TB, upper/lower GT40 Explorer intake, (8) 4-pintel 19# fuel injectors, plus a bunch of misc hardware for $145 total. I didn't end up using the explorer intake as I went with an SVO motorsport intake, but the point is there are deals out there if you look.

LAFENATU · Aug 6, 2009

Jesus...$80 for those heads??

That is dirt cheap. They usually go for around $300

Ryno8705 · Aug 6, 2009

LAFENATU said:
Jesus...$80 for those heads??

That is dirt cheap. They usually go for around $300

$40 per head with $5 core. So I guess I paid $90 because it was cheaper to not drive over there and back for $10. The rest of the stuff I mentioned only cost $65, $55 if you don't count the $10 I forfeited for the core charge. Bottom line, I left that day $145 less with all the parts I mentioned above.

My buddy and I pulled everything and that took an hour and a half-ish. I did buy him dinner after that for helping, which was an additional $10 at Taco Bell. You can skate by real cheap if you pull it yourself. The salvage yard could give a crap less about GT40 or anything else for that matter. All they care about is it's a iron SBF head. The Explorer intake, all he wanted to know is if it was aluminum or iron. The injectors were dirty as hell (on the outside) and I think he only charged me $1.50 each. I bought a $25 rebuild kit (pintel caps, filters, o-rings) and spent 1.5 hours cleaning them after I soaked them in carb cleaner in an ultrasonic cleaner. The injectors are on my car now, running like a champ and look like new. The Explorer 19# have a better spray pattern (4 pintle vs stock Mustang 1 pintle) and are the EV6 narrow body which look better.