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Alumuminum heads on an iron block are common. If 400hp cars can do it, so can you. Just be sure to torque them down properly, cutting corners will cost you.
 

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they relaly only strech for what he said above me and if your fire it up on a cold engine and then go beat the shit out of it.

Fawk GT40, save yourself some time, get either AFR's 180 or TrickFlows Twisted Wedge heads, or Brodix. Top of the line for better performance is allways smart!
 

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The Anti Yam!
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BuckingBronco93 said:
Fawk GT40, save yourself some time, get either AFR's 180 or TrickFlows Twisted Wedge heads, or Brodix. Top of the line for better performance is allways smart!
Precisely what is so bad about GT-40 "X" heads? I would like to know before I spend a lot of time installing my engine with these heads on it.

Oh and AFR doesnt make a 180 head for Ford small blocks.
 

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Practicing Infidel
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Gacknar said:
Precisely what is so bad about GT-40 "X" heads? I would like to know before I spend a lot of time installing my engine with these heads on it.

Oh and AFR doesnt make a 180 head for Ford small blocks.
Gackner

I know nuthin' bout GT-40 heads iron or aluminum and I wouldn't want to say anything bad about them, but after reading this article;

http://carcraft.com/techarticles/116_0307_ford/

I know AFRs are what I want, if I can ever justify the costs of aluminum heads !

Sixlitre
 

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Discussion Starter #6
are gt 40 heads any better than stock heads? i'm not building a race car i don't need a set of 2500 3000 dollar heads, im good spending a grand and upgraded set of heads. i was just wondering if bolting a set of aluminum heads to a cast iron block should cause an concern
 

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Sixlitre said:
Gackner

I know nuthin' bout GT-40 heads iron or aluminum and I wouldn't want to say anything bad about them, but after reading this article;

http://carcraft.com/techarticles/116_0307_ford/

I know AFRs are what I want, if I can ever justify the costs of aluminum heads !

Sixlitre
Quote: 405 hp at 6,200 rpm and 380 lb-ft of torque at 4,300,

I'm assuming you are talking about a Mustang that you are taking to the strip..because the engine in that article would be a total dog in a truck. My 408 makes well over 400 ft-lbs at 3000 RPM..which means that it has some utility in a full-size truck. I have a 331 stroker at the shop here with AFR heads..another dog if yr talking about truck engines. It does real well in the Mustang it was built for..once you get it beyond about 4800 RPM.
 

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badpony93 said:
are gt 40 heads any better than stock heads? i'm not building a race car i don't need a set of 2500 3000 dollar heads, im good spending a grand and upgraded set of heads. i was just wondering if bolting a set of aluminum heads to a cast iron block should cause an concern

As was already said people do it all the time. 90% of mustangs end up with aluminum heads on cast iron blocks. AFR's are a very nice head but there a little more spendy than the rest. The gt-40x heads, edelbrock, trickflow's are also very nice. It all depens what you want really. Since it's going in a bronco you want to retain most of the lowend torque and try not to shift the power band up to high. Runner size, valve size, and cam size all play factor's in those issues.
 

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I've had bad luck with aluminum heads here (PX,AZ) your milage may vary. Most of them I've been around have warpped.
 

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Discussion Starter #10
ok how about the gt-40p heads? or should i reach into the pockets. now keep in mind, it's a DD, weekend warrior but would like to be able to feel the power.
 

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badpony93 said:
ok how about the gt-40p heads? or should i reach into the pockets. now keep in mind, it's a DD, weekend warrior but would like to be able to feel the power.

If you go with p- heads you need to change out your headers. The spark plugs come out of the p-heads at a different angle then the stock heads. Thus putting your plug wires very close to the headers. I was thinking about tracking down a set of gt-40 iron's not p's. Giving them a fresh valve job and cleanup with some 1.7rr's stock cam and either porting the stock lower intake or getting the edelbrock performer truck intake. When all is said and done you should be into the heads between $300-600 depending how much you have to pay for the heads themselves.
 

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Shouldn't someone be worried about compression here and flow numbers? It doesn't mean shit what head it is, if your only flowing 60 in a set of $3000 heads, but can port the GT-40s to flow 65 for half the total cost, with a nice three angle valve job etc, then who cares? You can buy the most expensive heads but get them bench-tested first, and worry about compression as well.
 

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Now none of this has been experience with Bronco's, but on Mustangs, with that said

You will make more power through the curve with a set of TFS heads over a set of GT40 anything. Now say if you can get the GT40 heads at a good price that makes a little less power, then go ahead if you dont mind. I highly recommend not buying any used heads, unless its someone you know. You never know what happened to a set or if they had some problem, its not worth the money saved in the front end of the deal to off set the ability to have a new set you can bolt on with no worries. You dont have to worry about warping or different material or any of that, trust me I have had more than enough aluminum ford head motors put together. Just make sure you get new head bolts, Ford uses a torque to yield head bolt, so its a one time use.

Oh and as for compression, you will be fine with the GT40's or Trickflows, all works out fine.
 

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The Anti Yam!
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Sixlitre said:
Gackner

I know nuthin' bout GT-40 heads iron or aluminum and I wouldn't want to say anything bad about them, but after reading this article;

http://carcraft.com/techarticles/116_0307_ford/

I know AFRs are what I want, if I can ever justify the costs of aluminum heads !

Sixlitre
AFR makes some of the best performance heads in the world. The proper set of AFR heads will do absolute wonders for your Hi performance automobile. There is a good chance I will be placing AFRs on my Mustang.

But my Mustang doesn't way 6,000lbs

Here is what the car in the artical put out before the heads.
CarCraft said:
278 hp at 5,200 rpm and 315 lb-ft of torque at 4,100 on Westech Performance's SuperFlow 901 engine dyno.
But see, here is the problem
CarCraft said:
(with AFR 165) the little 302 produced a jaw-dropping 382 hp at 6,000 rpm and 368 lb-ft of torque at 4,200, a gain of 104 hp and 53 lb-ft solely from the heads and headers
See what happened there?

How often do you have your Bronco at 6,000rpm?
And 4,200 is a little high as well.

AFR 165's are greate in a light mustang with a mild 302, but they are too much head for a low reving 302 in a Bronco.

165's where to little head for my 351. AFR 185's where to much, I would have lost torqe with a 185cc intake runner and the 2.02 intake valve was to much for my engine. It would have moved my power band to high in the RPM range for my goals. The 185 also has a combustion chamber size of 58cc or 61cc, that would have put me at or over 10:1 compresion with my pistons, wich is higher than I wanted to try running on 87 octane pump gas.

My GT-40"X" heads have a 178cc intake runners and 1.94 intake valve. Exhaust runner volume is 62cc and it has a 1.54 exhaust valve. These heads also have a 64cc combustion chamber wich put me right around my 9.5:1 compresion goals. This head fals right between the AFR 165 and 185.

I ran many simulations with Desktop Dyno. For what I wanted, the GT-40 "X" heads gave the best tourqe and HP curve for my aplication. (Cam, Bore, stroke, etc etc) RLKBOB did the same but found that with his engine combination TFS heads gave him the results he was looking for. (his engine runs a diferant cam and he wanted a higher compresion ratio) So he whent with TFS heads.

You go with the parts that work best for you, not that work best on someone elses engine, in a completly diferant aplication. (I.E., Mustang to Bronco)

Choosing the right head involves more than just bying a certain brand. You have to take your engine and your goals into consideration. You want engine parts that complament each other.
 

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Cast iron will by far be the best bang for the buck. The aluminum weight savings is great for a mustang which needs the nose lighter for weight distribution during a launch. With our Bronco's the only difference it will make is in your wallet. Besides aluminum is much more prone to warping and causing a blown head gasket.
 

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93XLT said:
With our Bronco's the only difference it will make is in your wallet. Besides aluminum is much more prone to warping and causing a blown head gasket.
Actualy with Aluminum you can get away with a higher compresion ratio than with Iron. That means more power on less expensive gas.

Also, I am told that the warping problem has been eliminated from modern aluminum performance heads.
 

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I have seen a problem with aluminum heads on big HP engines on the spray. They wouldn't hold a headgasket, bolts were all right, headgaskets the best you can get, they were O-ringed though if that had anything to do with it.
 

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The aluminum head is a nice performance addition (no argument here) but if he plans on wheelin in arizona he should strongly consider the possibilty of over-heating his engine. This may not warp aluminum head but will certainly not hold up as well as iron will;do to the different expansion rates of the two different metal properties when mating aluminum heads to an iron block. He needs to decide if he would rather have performance or reliabilty.
 

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Gacknar said:
AFR makes some of the best performance heads in the world. The proper set of AFR heads will do absolute wonders for your Hi performance automobile. There is a good chance I will be placing AFRs on my Mustang.

But my Mustang doesn't way 6,000lbs

Here is what the car in the artical put out before the heads.


But see, here is the problem


See what happened there?

How often do you have your Bronco at 6,000rpm?
And 4,200 is a little high as well.

AFR 165's are greate in a light mustang with a mild 302, but they are too much head for a low reving 302 in a Bronco.

165's where to little head for my 351. AFR 185's where to much, I would have lost torqe with a 185cc intake runner and the 2.02 intake valve was to much for my engine. It would have moved my power band to high in the RPM range for my goals. The 185 also has a combustion chamber size of 58cc or 61cc, that would have put me at or over 10:1 compresion with my pistons, wich is higher than I wanted to try running on 87 octane pump gas.

My GT-40"X" heads have a 178cc intake runners and 1.94 intake valve. Exhaust runner volume is 62cc and it has a 1.54 exhaust valve. These heads also have a 64cc combustion chamber wich put me right around my 9.5:1 compresion goals. This head fals right between the AFR 165 and 185.

I ran many simulations with Desktop Dyno. For what I wanted, the GT-40 "X" heads gave the best tourqe and HP curve for my aplication. (Cam, Bore, stroke, etc etc) RLKBOB did the same but found that with his engine combination TFS heads gave him the results he was looking for. (his engine runs a diferant cam and he wanted a higher compresion ratio) So he whent with TFS heads.

You go with the parts that work best for you, not that work best on someone elses engine, in a completly diferant aplication. (I.E., Mustang to Bronco)

Choosing the right head involves more than just bying a certain brand. You have to take your engine and your goals into consideration. You want engine parts that complament each other.

Damn !

and I was so hot for those AFRs !!!!!!!!!!

I've done a dis-service posting that car craft article, as I have the actual magazine and it shows the dyno chart results, whereas the e-version doesn't.

Although the torque curve looks extremely flat, the chart doesn't give results lower than 2500 rpms, which is where many of our Broncos operate.

I will say those heads were already producing 325 ft/lbs of torque at 2500 rpms, compared to our stock maximum torque peak of 285 ft/lbs with a bone stock Bronco(wherever our stock torque peak occurs).

I was under the impression there were plenty of people running Mustang 5.0 litre transplants in their broncos. Given the magazine used a stock Mustang cam I figured the heads would stay tame and make their power lower than if they'd gone to a hotter cam ?

Like you say though compression has also to be factored into the equation too. I would think, with an engine as popular as a 302, we should be able to to find an off the shelf piston that would deliver just about any desired compression ratio using the AFRs.

With aluminum heads I know on Mopars the rule of thumb is; whatever you were getting away with at 9 to 1 in cast iron, you'll get away with at 10 to 1 in aluminum(fuel and heat wise).

Sixlitre
 
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