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Head's iron or alum?
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TSHACK
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PostPosted: Mon Jan 14, 2008 3:28 am    Post subject: Head's iron or alum? Reply with quote

Which is better alum or iron heads for a 350-400 sbc. used for brackets, street ect. I know alum is lighter & should cool better. Some people still say you can make more power with iron (I'm not sure on that one). It seems like most of you use alum. what your take.
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clay
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PostPosted: Mon Jan 14, 2008 5:44 am    Post subject: Reply with quote

I currently am running an iron Sportsman II head. I know Jeep_406 is also. 96capriceMGR I believe is iron headed too. There is no power advantage with an aluminum head if the ports are the same. I personally like iron heads better - I think they have to do a better job of head gasket sealing. They are stronger and have the same rate of expansion as the block so there is no head gasket scrubbing. Weight reduction, repairability, and ease of porting are the main advantages of aluminum. Clay
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squeeezer
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PostPosted: Mon Jan 14, 2008 7:57 am    Post subject: Reply with quote

imo the only way aluminum shines over iron is .........
if you want to run it on the street and you just gotta have a bigger cam....so more compression is required

you can run more compression with the fuel you are running
how else could you run 11.5 to 1 on the street maybe even 12 to 1 on pump gas
i guess in a nutshell the heat dissapation of aluminum is better for higher cylinder pressure

also cheaper to repair
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96capriceMGR
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PostPosted: Mon Jan 14, 2008 7:14 pm    Post subject: Reply with quote

I am running aluminums, with heavy porting the LT1 iron heads are known to crack over time. Plus pretty much all the LT1 R&D has been put into the aluminums.

I still think it is important to understand things though, the "better cooling" of aluminum is wasting more energy by pumping it into the cooling system rather than keeping it in the chamber where it can be used to expand gasses and push the piston.

It has advantages in detonation resistance though, I am running 11.2-3:1 compression 230psi cranking on 93 octane with a crappy .052 quench, keep in mind this is injected and reverse cooled.

Think the most important part is what exact heads are you looking at?
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clay
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PostPosted: Mon Jan 14, 2008 7:18 pm    Post subject: Reply with quote

Quote:
I am running aluminums

Oops, my bad on that one Embarassed . Clay
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squeeezer
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PostPosted: Mon Jan 14, 2008 8:15 pm    Post subject: Reply with quote

96capriceMGR wrote:
Think the most important part is what exact heads are you looking at?







BINGO!!!
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af2
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PostPosted: Mon Jan 14, 2008 8:43 pm    Post subject: Reply with quote

I will say a friend of mine that runs NEIII(9.60) bought a set of Brodix heads that out flowed his Bowtie's big time and he lost .4 seconds. He couldn't even qualify. He had to have the heads ported to get him back to running the 9.30's he was running?
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squeeezer
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PostPosted: Mon Jan 14, 2008 8:58 pm    Post subject: Reply with quote

af2 wrote:
I will say a friend of mine that runs NEIII(9.60) bought a set of Brodix heads that out flowed his Bowtie's big time and he lost .4 seconds. He couldn't even qualify. He had to have the heads ported to get him back to running the 9.30's he was running?





WTF??????
there has to be more to that story
is that all he changed????
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af2
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PostPosted: Mon Jan 14, 2008 9:50 pm    Post subject: Reply with quote

squeeezer wrote:
af2 wrote:
I will say a friend of mine that runs NEIII(9.60) bought a set of Brodix heads that out flowed his Bowtie's big time and he lost .4 seconds. He couldn't even qualify. He had to have the heads ported to get him back to running the 9.30's he was running?





WTF??????
there has to be more to that story
is that all he changed????


Yep! The Bowtie heads were cracked and he went with aluminum Brodix. Nothing except new rings were freshened.
The Bowties had excellent mid lift #'s and that I feel is the reason.
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TSHACK
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PostPosted: Tue Jan 15, 2008 1:21 am    Post subject: Reply with quote

96capriceMGR wrote:


I still think it is important to understand things though, the "better cooling" of aluminum is wasting more energy by pumping it into the cooling system rather than keeping it in the chamber where it can be used to expand gasses and push the piston.


96 caprice Do you think this power loss will nullify the weight saving. between say the edelbrock vic jr type (there seem to be several copies, pro line, procomp, ect) & say a set of ported double hump gm heads?

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jeep_406
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PostPosted: Tue Jan 15, 2008 9:20 am    Post subject: Reply with quote

I think almost any new design head would be better than the old double hump heads no matter what you did to the old cast heads. I run the cast Sportsman II's, mainly because that was what I could afford way back when. I also was able to do my own flow bench work which was a huge savings.
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squeeezer
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PostPosted: Tue Jan 15, 2008 4:29 pm    Post subject: Reply with quote

af2 wrote:
squeeezer wrote:
af2 wrote:
I will say a friend of mine that runs NEIII(9.60) bought a set of Brodix heads that out flowed his Bowtie's big time and he lost .4 seconds. He couldn't even qualify. He had to have the heads ported to get him back to running the 9.30's he was running?





WTF??????
there has to be more to that story
is that all he changed????


Yep! The Bowtie heads were cracked and he went with aluminum Brodix. Nothing except new rings were freshened.
The Bowties had excellent mid lift #'s and that I feel is the reason.






the valve springs MUST NOT have been up to the task
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96capriceMGR
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PostPosted: Tue Jan 15, 2008 6:53 pm    Post subject: Reply with quote

I am with jeep, the double humps should be left to resoration buffs, they SUCK in a big way compared to the newer options, hell with heavy porting I think they only equal the cheapest SBC head I know of as cast, the Vortecs.


Do not get caught up in the thermal efficiency vs. weight vs. compression arguments, figure out what you can afford understanding heads are the most important factor in power.

Also have to understand a flowbench is NOT everything, air in an engine is not steady flow and is wet. Look for cars runnning well with the heads you are considering and look for that to be CONSISTENT. I see some parts that get good reputations because 2 guys who make anything fast make them fast when the majority of guys using them have nothing but problems. In a case like that it is likely the wrench that is good not the product.
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clay
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PostPosted: Tue Jan 15, 2008 8:03 pm    Post subject: Reply with quote

I agree with 96capriceMGR on the airflow thing. Recently I have been doing some head research for a buddies BBC. We have been looking at what some companies like Shafiroff for one example are using on their motors. Look around and see what sucessfull and reputable companies are using - good information to be had on some of their sites. Dart seems to have a good thing going with studying wet flow in addition to quantity of airflow and seem to have a really good product. I definately think there is power to be had there. The work probably required for a set of heads as old as the double humps to be rebuilt and usable just wouldn't be justifiable considering what Vortec's can be had for. Clay
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af2
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PostPosted: Tue Jan 15, 2008 9:12 pm    Post subject: Reply with quote

Jeez guys, where the hell did the double humps come from? Mad
Aluminum and compression work! I was talking a simple pull off and put on not created by Car Craft!
And yes Sqeezer the springs were new! The heads also! Shocked
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