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GT-40 irons
Anybody know where to get some GT-40 irons? I've been going crazy looking for them. After all of the stories of Edelbrocks wearing the spring shims, Holley's burning oil, and loss of low end torque with any other heads, I'm kinda leaning towards these. Obviously, I'd like stone reliability.
------------------ Robert 91GT; 88 ASC McLaren #709 |
Forget the GT-40's and look for the GT-40P heads. They'll make more power and are alot more readily available.
------------------ Jeff Chambers T/S #3 11.611 Seconds/116.7 MPH Chambers Racing Team |
My only argument is that I'd have to buy $200 headers to go with them. If I'm going to lay out that kind of cash ($600+$200) I'd be better off getting the aluminum GT-40's. Which is where I may end up.
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Your best bet is to get a copy of a mustang publication and start calling some of the advertisers, you may get lucky in locating a set. Maybe your local speedshop will have the low down on a set from other customers.
You could find a set of used 351 heads from (I believe 76 and up) maybe an entire longblock and find a local shop to machine the heads and perform all the port and bowel work for a good price. A good deal of the publications stay away from this advice due to the money involved, but if you are set on an iron head with GT-40 specs then a 351 head would be a great place to start. Hopefully you have access to good machinist and fair pricing. Then you could top the head with your choice of valvetrain components. You would have the added bonus of doing some of the work yourself, if you are into the "hot rodding" image and don't wish to go the shop and bolt route. Nothing wrong with that, but just in case you wanted to follow a different route. [This message has been edited by Lexicon (edited 06-02-2001).] |
While the GT-40 Iron heads are significantly better than the stock units, they are not really worth the kind of money you'd spend to upgrade.
There are some drawbacks to the GT-40 iron heads. One major one is the combustion chamber size. At 65.5cc's it'll drop your compression down to about 8.8:1 from 9.0:1. The GT-40 doesn't flow exceptionally well at low lifts either. It's much like the Windsor Jr's and Sr's in that regard. They are very linear in the way the flow increases. Quite frankly, after looking at the flow numbers, I'm completely unimpressed with all three of those heads in stock form. Expect max flow out of the GT40's to be about 190cfm intake, and about 130cfm exhaust. Even with the larger than stock (and GT-40P) exhaust valves, the GT-40 iron seems to be deficient on exhaust flow. Valve sizes on the GT-40 iron are 1.84" 1.54" GT-40P 1.84" 1.46" E7TE 1.78" 1.46" The GT-40P heads make much better flow numbers at lower lifts, in addition they feature 59cc combustion chambers that will effectively raise your compression ratio to about 9.5:1. Coupled with the additional compression, and the additional lower lift flow (equal flow from about .400-.600) the GT-40P is significantly superior to the GT-40 Iron heads, and they are a great head with just a little exhaust work to get up to a better 80% of intake exhaust flow. I've also heard of deals as good as $400 for a complete set of GT-40P heads. It may be worth calling around in your area to locate a 1996-2001 Ford Explorer with the 5.0. If you can get a solid deal on the Explorer V-8's 5.0, you could be setting yourself up with a solid deal for performance. The 5.0 in the Explorer also comes with the Explorer intake, (GT-40 Lower/Explorer (nearly the same as the Cobra) upper.) |
Well, You kinda pushed me back to the 40p's again. I had originally thought about getting them! I guess that airflow "under the curve" is alot more important than peak. The 40P's seem to get that air flowing right away.
It doesn't sound like a bad combo...A 306 (my engine rebuilt) with a mild cam, GT-40P's, a Cobra intake and an off-road exhaust. If I get the tune right I should be making some decent power. What I'm really looking for is a reliable combo that will make some good power. It'll be kept below 5500 RPM's and I would like some great torque. You guys have me thinking... ------------------ Robert 91GT; 88 ASC McLaren #709 |
GT-40P heads, lightly port exhaust
E-303 cam, Explorer or Cobra intake. That combo is capable of making 320hp, and it'll keep your power band long and strong. Check on Ebay, I've seen good deals on used Cobra and Explorer intakes. |
Where in the world did you get your flow #'s from. The gt 4o's flow better then p's al over unless the p's are ported. Plus the p's lose exaust flow due to smaller valve at 400-500 lift. The p's only have a velocity advantange but not enough to outweigh the benifits of the GT-40's
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Courtesy of Fletch's Carbureted 5.0L webpage
Intake Flow @ 28" H20 .100" .200" .300" .400" .500" GT-40P 61 128 169 195 196 GT-40 54 107 157 183 192 E7TE 59 114 144 156 156 '69 351W 52 103 149 174 183 289 50 97 127 156 165 GT-40Y 64 114 167 199 213 GT-40X 53 114 170 207 226 Exhaust Flow @ 28" H20 .100" .200" .300" .400" .500" GT-40P 52 90 123 135 139 GT-40 47 94 119 128 128 E7TE 42 78 105 115 116 '69 351W 48 77 100 113 118 289 37 71 93 104 107 GT-40Y 52 98 128 137 134 GT-40X 50 106 139 153 161 Courtesy of FordMuscle.com GT40P .100 .200 .300 .400 .500 .600 Intake 61 125 166 195 196 190 Exhaust 50 89 120 132 138 144 http://home.isoa.net/~mharrisj/fordhead.html http://www.geocities.com/motorcitymustang/gt40p.html http://www.fordmuscle.com/archives/2...s/index1.shtml As you can see, FordMuscle.com got basically the same flow numbers as the above page. The GT-40P kicks the GT-40 Iron's *** quite frankly. What possibly possessed you to step and and talk about stuff you obviously don't know about? It's widely held that the GT-40P or 2nd GEN GT-40 head flows significantly better than the original GT-40. I spent a good week researching the heads, flow numbers, and reasons for the GT-40P heads begin better. I originally thought the GT-40 heads would have been better, but I never stepped in telling people they were wrong without researching like you just did. The GT-40P's eliminate most of the thermactor bump that chokes off exhaust flow, the ports are designed for increased flow velocity (more flow to people who don't know what that equates to), a smaller combustion chamber (increased compression about 3/4 of a point) further adding hp. You're an idiot if you think the GT-40 outflows the P on the exhaust side between 400-500 lift. See above reference to the thermactor bump. Also see above reference to better port velocity thanks to redesigned intake and exhaust ports. You really need to research your **** before you come in here spreading misinformation. |
In MM&FF june issue the GT-40 beat the GT-40p throught the entire range for intake and exhaust.
For comparison, my GT-40 irons (Fox Lake, stage III ported) peaked at 241cfm int@.600 and 198cfm@.600! These heads really like a port job but the iron is hard to port and a job like this costs a pretty penny. ------------------ GT-40 heads (ported, polished, + milled), B303 cam, 1.7rr's, JE pistons, Offy intake, Carter AFB 625cfm carb, Flowtech 1 5/8" shortys, Flowtech X-pipe, MAC Flowpath exhaust, MAC pulleys, 373's, subframes, Eibachs+Tokicos, B&M ripper, FMS Clutch, Zoom Quadrant+cable, 17" CSA Ultra rims, 235/45ZR17 Yokohama AVS S4's, MSD 6A ignition+coil, FMS 9mm wires, Carbed, Naturally Aspirated, and Nasty! [This message has been edited by red82gt (edited 06-05-2001).] |
Buddy I work for ford the GT-40
s A: flow much better after being cleaned up B: the P;s just dod a little better stock cause of small runners and velocity. ANd the small exayst valve will ALWAYS hurt as you step up the power. Yeah the GT40p gets it in but EXCUSE ME hows it get out. ITS a fricken truck head thats ford needed bottom end torque in to pull a 45oo pd truck. You got the p. You want a Cobra that spins to 5500 rpm and makes power up there ford dud out the old castings for the gt40's. Go read a nother magazine buddy. I DONT KNOW WHAT IM TALKING ABOUT. OK go get p's then feed this myth and make some special header company rich! I'll buy used cheap GT-40's and see-ya at the track! ------------------ |
I can speak from what I've seen running in competition. Nearly everyone (90% or more) running competitively in T/S has switched to the P head because it just flat-out makes more power. Flow numbers aren't everything. The combustion chamber in the P's is superior, the exhaust port is superior, the spark plug placement is superior, and the deck thickness is superior, just to name a few.
We run the heads un-ported with a small (.500") cam, either carbed or EFI, and we've got guys making 340-370RWHP. You do the math, that means 425+ at the crank. Not a small feat. That's with shorty headers and stock sized valves too. I've had both GT-40 and GT-40P heads prepped basically the same way (gasket matched to 1250 and 1415 gaskets) and even though the flow numbers were very close, the P's make abundantly more HP. I think their key is runner velocity...they absolutely love it and its what makes the small valves work. Don't discount them if you're in the market for iron heads. With a nearly endless supply of them at $200 a pair (bare), they're a very economical HP bolt-on. Look at the guys running in Pure Street too. Tom Payne set the record last year at 11.09@122+ with a set of P heads. Just my $0.05. ------------------ Jeff Chambers Trophy Stock #3 11.611 Seconds / 116.7 MPH Chambers Racing Team |
Dam you Chambers!
I had just decided on a pair of Edelbrock head, and you've sold the idea of the GT-40P's on me and now I've changed my mind again! Bastard http://www.mustangworks.com/msgboard/biggrin.gif Oh and what intake matches the GT-40P real well, the Cobra? http://www.mustangworks.com/msgboard/smile.gif This stuff can be so confusing some times... ------------------ Driving: 1998 F-150 Far way in Edmonton==> :( 1995 Mustang GT |
Darn near any intake will work with the 1250's. GT-40, Cobra, Explort, Edelbrock Performer & Performer RPM, TFS, Holley; etc. You name it and it'll almost absitively, positutely fit. I've got a GT-40 system for sale right now; upper & lower, 1/2" spacer, new gaskets and all the bolts (I just upgraded to a Performer RPM). Best yet, the manifolds are already gasket matched and milled so they'll work real well with a set of heartily prepped GT-40P's. Any takers? I've even got real recent flow numbers on the combination.
------------------ Jeff Chambers Trophy Stock #3 11.611 Seconds / 116.7 MPH Chambers Racing Team |
hey, i know they aren't irons, but what about the GT40X heads??? how do they stack up against the p or the plain gt40's?
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I know a lot of idiots working for the auto industry. In fact, I don't know how many times I've heard some guy at Ford spouting of misinformation. Like the SN95 4.6L's are faster than the SN95 5.0's or the SN95 as a whole are quicker than the Fox's. The SN95's have more hp too, according to a bunch of guys working for Ford that I talked to. Excuse me if I don't care if you change the oil on Festiva's. Hope you're not confusing the pre production GT-40's with the real deal. Better look again. I've seen the GT-40 tested with 1.94" intake vavles, supposedly stock. There are my flow numbers. Tested and recorded. You give me the names and the articles of who did the flow testing and we'll see there, bucko. Until then, kiss my *** , cause all you've done is said well I read somewhere... Give some references with your bullshit. |
Unit your use of insults are laughable. At age 14 I might of gotten angry. First I work as a ford line tech so I don't swallow thier corporate bullshit. Second I do believe that I agreed on port velocity being better on the p's. I conceded that. But the exaust valve is too small. Ariticle and flow #'s by Brian Wolfe from may 95 super ford. Ever hear of Wolfe probably not. Practically poineererd getting stock headed stangs and such into the 11's while most guys gave up (like me) and went to a supercharger. Here are my #'s old but I hope you except them. GT40 (no not the clssic 60's ones either) the ones from the early 90's) as cast
in ex .1 60 53 .2 113 99 .3 153 125 .4 187 138 .5 209 142 Home ported (ya know an idiot like me) intake exaust .1 64 59 .2 122 104 .3 171 140 .4 198 169 .5 217 173 e7's Professionally ported intake exaust .1 62 51 .2 122 84 .3 157 113 .4 187 129 .5 196 139 The home ported GT-40's that can be done by a 'festiva oil changing idiot like me are good for 13.24 at 110 better times for a better driver Wolfe said hecouldent belive the strettable torque of the ported e7's (velocity) there is that word again. My exasut ported and mild intake gasket mathing gave a guy a 6-7 mph increase! Not bad for and idiot porting. I sold him the used heads for 500$ and he needed no special headers. So there are my #'s! I hope wolfe is a good name for you and ck out the super ford 1991 when we had to invent ways to make power not buy cold air pipes and By truck heads that need special headers. Dollar for Dollar used proven ad already probably have good hardware in em the gt-40s hands down. Fully port them and you have a good street/strip head. Or listen to the # toters that get all there information from mags too and buy P's the headers the plug wires. And join the me too crowd. Or buy used 40's from a trustworty guy and go fast for cheap. ANd 200 is for bare castings and unless you can pick your own valves grind em install good seats (even an idiot like me can) your still talking 1000$ for good parts. Oh yeah dont forget the headers. ANd buddy come to New york and I will kiss your after you prove to me you can assemble a bare head by yourself. Im going over our #'s and either formuscle or Brian Wolfe's reading suck peroid. MY #'s piss all over yours but to be so off kilter like that. I'm only going up to .500 and those #'s are better then your .600. Don't know what to say now. Wxcept I know how to port heads and assemble them do you? Or does ford muscle do yours? [This message has been edited by Francismaximus (edited 06-05-2001).] |
Your stock GT-40 numbers are considerably worse from .100-.400 lift on intake. Better at .500.
Who in the hell is running .600 lift on a set of iron GT-40's? That's like an X-303 with 1.7 rockers! An E cam with 1.6 rockers will put you at .498/.498. I'm not seeing the advantage of your numbers being better at .500 when the E cam never gets there. If you are building a serious engine, there is no way in hell you'd pick a set of iron heads flowing under 200cfm, or 205 with a .600 lift cam/rocker combo. The GT-40P's weren't designed to flow at .600 lift because it makes no sense to run them there. Hell, the stock HO cam .444/.444 has been getting people into the 12's for years. People are making over 400hp N/A with the E cam and aftermarket heads. The only way your .600 lift figure should EVER come into the equation is on a stroker, or a much larger displacement engine than a 302. Putting a .600 lift combo on a 302 is stupid. All you are doing is wasting tons of engine power lifting a valve way the hell up there. Going with an increased duration cam and sacrificing idle quality is a better route for such a wild combo. You'll get better power production with it because you won't lose so many hp lifting valves. Two different flowbench's both shouldn't be off. Based on your flow numbers (the early GT-40's seem to flow better), the P head, and the iron head are nearly the same for flow on exhuast, the GT40P flowing more intake until .500 (max lift that it should ever really see). Based on the flowbench numbers I posted, with links to the sites, the GT-40P outflows the GT-40's everywhere. As far as the pricing on the GT-40, I haven't seen a used set for less than $400 in a good long time. The E7TE is also a "truck" head. Guess the old truck heads are pretty decent? Maybe you can discard the GT-40P because it's a truck head, but appearently Wolfe can get stock "truck" heads to really perform, don't know why he wouldn't be able to get better stock truck heads to perform even better. I guess jeff chambers said it best "Nearly everyone (90% or more) running competitively in T/S has switched to the P head because it just flat-out makes more power." |
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It may not have been a very nice thing to say, but unit that line totally made my day! I'm still laughing at it.... Ah...**** that was a good one.. |
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