GT-40 vs worked E7's

fiveoho · Jan 8, 2007

i have searched but cant seem to get the answer i want. im sure you guys can help...

first off, please clear up the difference between GT-40 and GT40P heads. which one has header and spark plug issues...or both ( on a 95 )? what is the max lift of the springs that came in each?

now, im sure this may get into opionion but fire away: which heads will be better suited for a 306 tfs street heat, tfs 1 cam, 70mm tb, 75mm ma, 24lb, mac shorty headers?....

stock GT-40s ( freshened from machine shop ) or ported/milled .020" E7 heads with .550 springs?

how much difference would be between these? would i get into fitment problems on my 95 with the GT40s?

thanks guys

Grn92LX · Jan 8, 2007

GT40's.

By the way, you went from planning on afr 185's to ported e7's or gt40's?

fiveoho · Jan 8, 2007

Grn92LX said:
GT40's.

By the way, you went from planning on afr 185's to ported e7's or gt40's?

sold the 185's. im well aware that the afrs are far better heads. priorities came about so i will be doing more of a budget build.

fiveoho · Jan 8, 2007

Grn92LX said:
GT40's.

is the GT40 'P' head the ones that give you the fitment trouble and the the GT40 head will just bolt up and its all good? or do i have that totally wrong?

final5-0 · Jan 8, 2007

Done Correctly ... ported E7's would be better than stock GT40's

Can't say for certain but I'd bet the same could be said for the P's

I base that upon the P's ain't really all that much better than regulars

Of course ... Port the regulars or P's and that could be different

I'd keep beating the bushes for some used TFS, Edel, or AFR's

Note: TFS will not allow you to use oem style ped rockers
so
they aren't always the bargain it seems when first considered

Grady

fiveoho · Jan 8, 2007

thanks grady

will the gt-40s cause problems with the plugs and headers?

final5-0 · Jan 8, 2007

fiveoho said:
thanks grady

will the gt-40s cause problems with the plugs and headers?

No

The P heads are the only OEM Iron heads with those issues I've heard about

Grady

fiveoho · Jan 8, 2007

final5-0 said:
No

The P heads are the only OEM Iron heads with those issues I've heard about

Grady

the answer to the million dollar question! thanks bud!

grady comes thru again

fawcett · Jan 8, 2007

Whats the difference between gt40's and gt40x's?
I have the X's and I have no idea.
(and yeah I wish I had better heads but they're all I could afford at the time)
-fawcett

blksn955.o · Jan 8, 2007

The reg. gt40 heads flow less than the P's stock for stock. Most seems to be from the smaller exh. valve on the P's that gets better air volocity.

With the P heads they have the plug issue. In a port vs. port of gt40 and gt40p's the P's cannot be ported as much due to a revised water passage in the casting that will not allow the P's to be opend up as much as the reg. gt40's...so ported to ported the reg. gt40 heads "should" outflow the p's if done well...but prob. not by that much.

The X and Y gt40 heads should be alum. heads. They flow alittle more (newer design and not ever put on a production auto) and IIRC one if not both are not smog legal. They seem to be and OK head...in that they are better than stock iron heads but for the cost TFS or AFR heads would prob. be a better choice.

Thumper460 is the guy who knows what is up with the E7's and he has them flowing more than P's. He also does a HELOVA job on gt40 heads...mine look awsome...just the damn thing is fighting me tooth and nail to get some good numbers out of it...but I will get there. TOP notch work on iron heads, he has some good "kits" that cost about what a machine shop charges to mill/freshen/spring a set of heads that he does also with the port work...VERY not bad.

fiveoho · Jan 8, 2007

i would really like to have a set of thumpers.....for the price

thumper460 · Jan 10, 2007

HMMmmmmm....... Ported E7's... then stock GT40's... Then GT40P's !! The way of the future is snag a set of 40's off the explore ( and intake )! Have the Heads ported / worked/ new performance springs.. and the Lower matched to the heads.. and your there!!!! as long as you can snag the explore 40's set up.. that IS the best deal!!

Just me........................................

Thumper

fiveoho · Jan 10, 2007

thumper460 said:
HMMmmmmm....... Ported E7's... then stock GT40's... Then GT40P's !! The way of the future is snag a set of 40's off the explore ( and intake )! Have the Heads ported / worked/ new performance springs.. and the Lower matched to the heads.. and your there!!!! as long as you can snag the explore 40's set up.. that IS the best deal!!

Just me........................................

Thumper

heres what i really want.....

http://classifieds.stangnet.com/showproduct.php?product=39297&cat=3

thumper460 · Jan 11, 2007

Cool.. give me a email...

Just me........................

Thumper

MustangGT95 · Jan 24, 2007

Are the GT40's a true bolt on 40hp like they claim? I have an f150 motor so I have no idea what heads I even have. But I just won some GT40's on ebay for a decent price.

GreenStangGT · Jan 24, 2007

MustangGT95 said:
Are the GT40's a true bolt on 40hp like they claim? I have an f150 motor so I have no idea what heads I even have. But I just won some GT40's on ebay for a decent price.

So you were who I bid against, sigh. I'm broke for the moment but was hoping I could snag them for a song. No such luck.

MustangGT95 · Jan 24, 2007

lol sorry man. I was watching his intakes and saw the GT40's on there. Put a bid in for 335 and went out to eat. Came back and I won them for 330. Honestly I was suprised.

GreenStangGT · Jan 24, 2007

No problem, not your fault, mine for being cheap/broke lol.

Sorry to derail the thread for a moment, continue on...

final5-0 · Jan 25, 2007

40 HP from a set of GT40's

Well ... if that is 40fw they are talking about
Then ... thats about 34rw for a stick trans

The Question I would have to ask is .....

That gain is from nothing but a head swap

I'm not so sure about that

Grady

thumper460 · Jan 25, 2007

Yes.. I think that number is pretty big.. and probably the BHP ( flywheel) we are pulling 30-40 WHP on the ported head, I guess stock replacement depends on the how restrictive the heads are that you pull off.. like a D8 or a D3 smog head!!

Theyare good heads .. and the explore deal rocks!! There are guys here getting the INTAKE and HEADS for 400.00 !! of course as soon as the junk yards realize the value.. it has to go up!! Yes!!

Just me.............................................

Thumper

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