Actually the production irons are very thin on the intake side and need work to prevent deflection under high pressures. Tom at Champion has a good solution for this. The aluminum heads available have addressed this quite well.A little "birdy" who has been around buick racing for a long time, had this same discussion with me. You can run more boost to make up for the lack of valve size in the iron head vs. the alumimum head. Iron heads tend to hold a gasket better.(more weight, etc..) The same birdy told me they made the same power on a test car with alum. heads @ about 4-5 psi less then irons. I will be testing the outer limits of some Iron heads soon...will report back.
Aluminum vs Irons
- Thread starter J-B Racing
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With the proper engine buildup and a set of race ported aluminum heads with a matching aftermarket intake and a tangential 4 bolt turbo should make a lot more power at much less boost than a similarly built iron headed engine with a maxed out stock intake and 3 bolt turbo. Compression ratio needs to be increased and timing needs to be adjusted a few degrees to get back the thermal efficiency, but the aluminums flow way more when maxed and therefore will make a lot more power. The quickest and fastest production style headed Buicks all run aftermarket race ported aluminum heads. I'll have a lot of feed back on the race ported Champions in the spring/summer. I plan on running in the 10.20 range with the blue car on a 9.3:1 109 engine under 23psi boost and mid 9's with the stage 2 and Champion R's race ported on a 9.7:1 motor. I dont plan on running more than 25 psi on the stage 2 either. Keep in mind none of these cars will need to conform to any of the class racing rules since i dont care about racing in a class that is not a true street class. Besides they dont allow the use of N2O:wink: .
jasjamz
THS Racer
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What do you think it would have went with the GN1's out of the box?(unported)
ttypewhite
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jasjamz thats hard to say, i would be guessing which serves no purpose as it did not happen however i would say low 10's.
Roy and Laz have hit low 9's with iron heads on a 109 motor. I don't recall what turbo they were running or if they were at legal weight. Walt judy has run 9.6's with a TSM legal iron headed 109. We run T/A SE heads and have found that we can dry up a 70GTQ. WE can't get the boots over 28lbs and it falls off to 24lbs at the end of the run. There's more to it than just the heads. The cam plays a big part of it too.
With that being said, in a turbo limited class is better to run a less restricted head with less boost or a restricted one at higher boost? Its all about how much air you can cram into the cylinders. Right now D. Kerney has the TSM record of 9.14 @ 148.8 mph with Champion GN1 R heads.
With that being said, in a turbo limited class is better to run a less restricted head with less boost or a restricted one at higher boost? Its all about how much air you can cram into the cylinders. Right now D. Kerney has the TSM record of 9.14 @ 148.8 mph with Champion GN1 R heads.
TSM cars are like building a Super Stock. Can`t share all the secrets...RIGHT
The biggest secret we have found is it's not so much the combo you run but how it is tuned. It's not how much boost can you make, it's where you make it at.
GNBRETT
Pelennor Fields
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The overall numbers dont lie. Aluminums are on most all low 9 sec cars.
No doubt. The point I was making is it has been done with irons. In class racing like TSM, you have to ask yourself is it worth the the extra work to gain the weight break for iron heads? At some point the turbo will be the limiting factor not the heads. Just for thought, someone told me awhile back that boost is the air that an engine can't use.
That's what I would think too. But this is not the first time I hear about this.
One person told me that it has to do with the Temp in the Runners...
This is getting confusing.
If that was the case one should allow a hotter coolant temps on the alum heads to counter act this problem.
J-B Racing
Forced Induction
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email
This is an email I got from a Board member who I find is close to Einstein....
Hi Joe,
There are two ways that the aluminum head can give you less HP than an iron head. It all has to do with the difference in rate of heat transfer between the two materials.
With the aluminum head, the intake port will easily transfer heat from the cooling jacket to the intake charge. We know that the cooler the intake charge is, the denser and the more HP. The combustion chamber will quickly transfer heat from the combustion event to the cooling jacket. We know that heat and expanding gases from the combustion event is what makes HP. The aluminum tends to quench some of the heat generated from combustion. That is why aluminum heads tend to be more detonation resistant than iron heads.
To solve the heat transfer problem of the aluminum heads, coat the intake port and the combustion chamber with a heat barrier coating.
Sincerely Yours,
This is an email I got from a Board member who I find is close to Einstein....
Hi Joe,
There are two ways that the aluminum head can give you less HP than an iron head. It all has to do with the difference in rate of heat transfer between the two materials.
With the aluminum head, the intake port will easily transfer heat from the cooling jacket to the intake charge. We know that the cooler the intake charge is, the denser and the more HP. The combustion chamber will quickly transfer heat from the combustion event to the cooling jacket. We know that heat and expanding gases from the combustion event is what makes HP. The aluminum tends to quench some of the heat generated from combustion. That is why aluminum heads tend to be more detonation resistant than iron heads.
To solve the heat transfer problem of the aluminum heads, coat the intake port and the combustion chamber with a heat barrier coating.
Sincerely Yours,
Jason, what's the fastest you've been with those unported 8 bolt GN1s?
Dusty Bradford
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I don't doubt the theory but I'd have to see some hard data showing even a small increase in air temp entering the chamber with an aluminum head. I work with heat exchangers every day and can tell you an open pipe with a air flowing through it will not pick up any heat even with a blow torch heating the pipe. You need surface area to exhange heat....just like an intercooler. You think about how fast the air is flowing through the runner and I seriously doubt there's a noticeable difference in air temp between iron and aluminum. It's true about the detonation resistance though.
J-B Racing
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You think about how fast the air is flowing through the runner and I seriously doubt there's a noticeable difference in air temp between iron and aluminum. It's true about the detonation resistance though.[/QUOTE]
Dusty
That is something that was my mind as well...
Joe
Dusty
That is something that was my mind as well...
Joe
Underboost
Mr. Dull
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A little "birdy" who has been around buick racing for a long time, had this same discussion with me. You can run more boost to make up for the lack of valve size in the iron head vs. the alumimum head. Iron heads tend to hold a gasket better.(more weight, etc..) The same birdy told me they made the same power on a test car with alum. heads @ about 4-5 psi less then irons. I will be testing the outer limits of some Iron heads soon...will report back.
I can tell you first hand Iron heads don't hold a gasket better. Alum heads conform to the block. Iron heads stay flat intern they lift.
Dusty
That is something that was my mind as well...
Joe[/QUOTE]
thats whats i was thinking. but the amount of heat lost thru the cooling is greater with the alum heads vs the irons. heat creates cylinder pressure also promotes a more effiecient burn of the fuel. i have seen several SBC guys unbolt a set of iron heads and add some alum heads the A/F ratio be about the same but lost some et/mph. but gained it back when allowing the coolant temps to get a tad hotter due to the amount of heat lost in the chamber. this is the reasont he alum heads can tolarate more boost before knocking over the iron heads.
I may be wrong this is what i have seen.
Underboost
Mr. Dull
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Thats with a 236/230 Cam @ over 600 lift
