gt40 vs. aftermarket cast iron - MustangForums.com

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gt40 vs. aftermarket cast iron

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Old 01-24-2011, 11:18 AM
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stdyhand
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Default gt40 vs. aftermarket cast iron

Hi, new to the forums. I had a question regarding performance from Cast Iron heads. First off I have chosen to use cast iron for its durability since my Fox is used primarily as a daily driver. I am aiming to get the most I can get out of cast iron, best bang for the buck. It is my understanding that cast iron and aluminum flow the same and that the only difference is the latter is considerably lighter, which obviously has its benefits.

My question is which would be better, a set of Ported GT40 or GT40p heads or an aftermarket pair of cast iron heads such as Dart, World Racing, or RHS?? I didn't see cast iron offered by other manufactures such as TFS, Edelbrock etc.

I am aiming to put on h/c/i to get better performance right now. However, there is a good chance that in the future the block may get stroked out to a 331 with all forged internals so I want to keep this in mind as well.

I've been told that ported GT40's may flow better than aftermarket cast iron heads but that the aftermarket set could still be ported more because there would be more metal on it. Anyone know if this is true??

If the performance is about the same then would it not be cheaper to just port the GT40's and rebuild them with new valves, springs, etc?

Any info you can give would be much appreciated. If anyone has bench tests on any of this that would be great
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Old 01-24-2011, 12:11 PM
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AdderMk2
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whatever course you choose. I strongly advise that you stay away from RHS heads.
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Old 01-24-2011, 02:03 PM
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alexyikes00
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Im not sure if this is true in your case.. but I heard that depeding on the work on the iron heads.. cant you get pretty close to the price on a set of good new aluminum heads?... I mean if the diffrence is around $150 bucks, i would just buy new aluminum heads..

just suggesting..lol
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Old 01-24-2011, 05:45 PM
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uedlose
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there is a set of TFS High Ports over on another site that starts with a C that are brand new the old iron version they work real good and can be ported to no end. But keep in mind they have been out of production for years but they are a mirror copy of the aluminum ones just iron from back in the day. I had a friend that use to run a set and they are good heads but they are very heavy and take a raised port header some have used stock also. As far as the others like the Darts they work well also I really dont know much about the RHS heads But I know of a few people that run them and they are fast running cars and have had no issues with them.
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Old 01-24-2011, 06:20 PM
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Venomantidote95
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U wont have a vast selection if u go iron. U can get good iron heads to do the job. U just add weight ofcourse. Depending on ur power goals and engine spec u could have heating and detnation problems since the iron heada retain the heat longer than aluminum.
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Old 01-25-2011, 02:42 AM
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Originally Posted by Venomantidote95 View Post
U wont have a vast selection if u go iron. U can get good iron heads to do the job. U just add weight ofcourse. Depending on ur power goals and engine spec u could have heating and detnation problems since the iron heada retain the heat longer than aluminum.
I thought iron was better for heat, thus less likely to warp or crack. Your saying it could be a problem. Why is the iron worse when it comes to the heat?
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Old 01-25-2011, 06:42 AM
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there is noting wrong with a iron head all being the same iron vs aluminum iron can make more HP due to retaining heat in the cly. offering a better burn of the fuel. But it can also cause detonation due to holding heat longer get your tune on. as far as warping and or cracking iron dose that to and is much heavier. with aluminum you can usually run more compression then iron due to the heat also in the cly. aluminum does not retain the heat.
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Old 01-25-2011, 06:58 AM
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mjr46
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Originally Posted by stdyhand View Post
I thought iron was better for heat, thus less likely to warp or crack. Your saying it could be a problem. Why is the iron worse when it comes to the heat?
if your cooling system is in working order, it's a mute point
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Old 01-25-2011, 12:48 PM
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Originally Posted by uedlose View Post
there is noting wrong with a iron head all being the same iron vs aluminum iron can make more HP due to retaining heat in the cly. offering a better burn of the fuel. But it can also cause detonation due to holding heat longer get your tune on. as far as warping and or cracking iron dose that to and is much heavier. with aluminum you can usually run more compression then iron due to the heat also in the cly. aluminum does not retain the heat.

Thanks for clearing that up!
Its hard to fully explain things from a mobilez
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Old 01-25-2011, 09:13 PM
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Assuming I did go with Aluminum, it would likely be the AFR 165 since the intake valve would fit the stock pistons. My concern would be whether these heads would still be ok once the block was stroked out.

If so, then my next question would be is it better to have the AFR's flowing 165 or another set flowing 185.

I seen another set of heads, can't remember if they were iron or aluminum, but they had a 1.94 intake valve and flowed 185. I THINK they were iron eagles but don't hold me to that. I know RHS had a set they "claim" moves 180 or more with the smaller valve.

Now I know AFR has a very good repuation and it is because of that I would be willing to pay a little extra for them; however, other sets are offering what they claim to be a higher flowing head with the same size valve and at a cheaper price.

It is my understanding and correct me if I'm wrong, but moving more air through a smaller valve results in more of a whirl into the cylinder and thus more low end torque.

Is it safe to assume the other heads, being advertised as a higher rate of flow can be compared to the AFR's? I was wondering if the AFR's could actually be ported further to get 180+ but I don't know if it would really matter with the smaller valves and being used on a stroker later.
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