Iron heads or aluminum???
12-11-2004, 07:36 AM
#1
Burning Brakes
Thread Starter
Iron heads or aluminum???
I am in need of some heads, since my 86 iron heads suck. I need heads that are going to give me a very good increase of power. I have been looking at Dart Iron Eaglee heads? What do you guys think of them? What are the advantages and disadvantages between iron and aluminum? I am not even sure what size I will need, if I need straight or angled plugs, or anything else. I have all the mods in my sig, and I plan on adding a whole Accel Super Ram setup, and changing cam to a much bigger one. I want a somewhat decent idle, but I want alot more power than I have. So with that in mind, and with my current exhaust mods, what size heads and what cam would be good for me to get? I am just doing the homework right now, but I plan on doing the head and cam swap very soon. I was looking at the iron eagle 190cc, 210cc,220cc, and 230cc. What would be best for maximum power? I also plan to upgrade rear to D44 and higher stall torque converter later on too. Tell me what you guys think. Thanks!
12-11-2004, 08:06 AM
#2
Le Mans Master
My vote is for aluminum, hands down winner.
Aluiminum heads are:
Lighter, which improves weight distributon and handling,
More easily repaired if damaged,
Allow you to run about one point more in compression ratio without getting into detonation which translates into more HP and TQ and Generally have better ports that flow better
The old theory that iron heads make more power due to better heat retention has been recently put to the back to back dyno tests by one of the mags and found not to be true.
With a 350 CID engine, stay under 200ccs on the intake port volume. around 190 would be about right.
You don't want to just consider maximum horsepower production when selecting a set of heads. Since the engine is seldom at maximum horsepower, what's more important is the power range that the engine usually sees. Opting for a Max HP head will usually cost you driveability (throttle response, low end torque, etc.) down low in the band.
To get maximum horsepower you will usually have to opt for a set of heads with BIG intake port volume which generally hurts flow velocity at lower RPMs.
Another point, don't get fooled with high flow numbers. What you want is the greatest flow AND the smallest intake port volume. That'll mean the velocity is up.
You also want a set of heads that the general consensus is they are trouble free with precision machining and using quality parts.
Stick to the well known brand names; companies that have been around since day one and have a solid reputation.
My thoughts.
Jake
Aluiminum heads are:
Lighter, which improves weight distributon and handling,
More easily repaired if damaged,
Allow you to run about one point more in compression ratio without getting into detonation which translates into more HP and TQ and Generally have better ports that flow better
The old theory that iron heads make more power due to better heat retention has been recently put to the back to back dyno tests by one of the mags and found not to be true.
With a 350 CID engine, stay under 200ccs on the intake port volume. around 190 would be about right.
You don't want to just consider maximum horsepower production when selecting a set of heads. Since the engine is seldom at maximum horsepower, what's more important is the power range that the engine usually sees. Opting for a Max HP head will usually cost you driveability (throttle response, low end torque, etc.) down low in the band.
To get maximum horsepower you will usually have to opt for a set of heads with BIG intake port volume which generally hurts flow velocity at lower RPMs.
Another point, don't get fooled with high flow numbers. What you want is the greatest flow AND the smallest intake port volume. That'll mean the velocity is up.
You also want a set of heads that the general consensus is they are trouble free with precision machining and using quality parts.
Stick to the well known brand names; companies that have been around since day one and have a solid reputation.
My thoughts.
Jake
Last edited by JAKE; 12-11-2004 at 08:08 AM.
12-11-2004, 08:35 AM
#3
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While Dart iron heads are very good, youre still better off with aluminum. Dart Pro 1's are good.
On an L98, you dont really want more than 180cc, but if you go with Superram then 190-200cc is better, and with MR I'd go with a little bigger than that, say 210cc.
On an L98, you dont really want more than 180cc, but if you go with Superram then 190-200cc is better, and with MR I'd go with a little bigger than that, say 210cc.
12-11-2004, 01:04 PM
#5
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I siwtched to a set of ported Dart Iron Eagles (200cc runners, 64cc chambers) recently.
The heads , breathless Air pump elim kit and 52mm TB made me drop a whole second in my 1/4, from 13.3's to 12.3's and that was with a slipping tranny.
I like them, and my major deciding factor was that with the Dart Irons I have I didn't have to change anything with Emissions. With aluminum heads you will have to have a bung welded to your exhaust and you will NEED to get an aftermarket, or 87+ lower intake manifold, to route the EGR gases to the headers/exhaust to stay emissions legal.
The heads , breathless Air pump elim kit and 52mm TB made me drop a whole second in my 1/4, from 13.3's to 12.3's and that was with a slipping tranny.
I like them, and my major deciding factor was that with the Dart Irons I have I didn't have to change anything with Emissions. With aluminum heads you will have to have a bung welded to your exhaust and you will NEED to get an aftermarket, or 87+ lower intake manifold, to route the EGR gases to the headers/exhaust to stay emissions legal.
12-11-2004, 01:10 PM
#6
Originally Posted by MrNuke
I siwtched to a set of ported Dart Iron Eagles (200cc runners, 64cc chambers) recently.
The heads , breathless Air pump elim kit and 52mm TB made me drop a whole second in my 1/4, from 13.3's to 12.3's and that was with a slipping tranny.
I like them, and my major deciding factor was that with the Dart Irons I have I didn't have to change anything with Emissions. With aluminum heads you will have to have a bung welded to your exhaust and you will NEED to get an aftermarket, or 87+ lower intake manifold, to route the EGR gases to the headers/exhaust to stay emissions legal.
The heads , breathless Air pump elim kit and 52mm TB made me drop a whole second in my 1/4, from 13.3's to 12.3's and that was with a slipping tranny.
I like them, and my major deciding factor was that with the Dart Irons I have I didn't have to change anything with Emissions. With aluminum heads you will have to have a bung welded to your exhaust and you will NEED to get an aftermarket, or 87+ lower intake manifold, to route the EGR gases to the headers/exhaust to stay emissions legal.
a full second is around 100CHP, WOW!!
that is awesome....
12-11-2004, 02:11 PM
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Originally Posted by MrNuke
I siwtched to a set of ported Dart Iron Eagles (200cc runners, 64cc chambers) recently.
The heads , breathless Air pump elim kit and 52mm TB made me drop a whole second in my 1/4, from 13.3's to 12.3's and that was with a slipping tranny.
I like them, and my major deciding factor was that with the Dart Irons I have I didn't have to change anything with Emissions. With aluminum heads you will have to have a bung welded to your exhaust and you will NEED to get an aftermarket, or 87+ lower intake manifold, to route the EGR gases to the headers/exhaust to stay emissions legal.
The heads , breathless Air pump elim kit and 52mm TB made me drop a whole second in my 1/4, from 13.3's to 12.3's and that was with a slipping tranny.
I like them, and my major deciding factor was that with the Dart Irons I have I didn't have to change anything with Emissions. With aluminum heads you will have to have a bung welded to your exhaust and you will NEED to get an aftermarket, or 87+ lower intake manifold, to route the EGR gases to the headers/exhaust to stay emissions legal.
12-12-2004, 12:17 PM
#9
Race Director
Originally Posted by #70SM2
Question: what is a "breathless Air Pump Eliminator Kit"?
www.breathlessperformance.com
12-12-2004, 09:42 PM
#10
Le Mans Master
Hmmm, I've heard that you can actually make more power with Iron heads than with aluminum. However to do that requires big bucks so I'd say go with aluminum heads if your budget isn't so big and you want a reduction in weight. They also transfrer heat better than iron and you don't have to worry about them rusting like my brand new heads started to do! 
I hear nothing but praise for Fast Burn aluminum cylinder heads. They're around $550 a piece and you probably couldn't go wrong with those.
I hear nothing but praise for Fast Burn aluminum cylinder heads. They're around $550 a piece and you probably couldn't go wrong with those.
12-12-2004, 10:20 PM
#11
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Originally Posted by 1985 Corvette
Hmmm, I've heard that you can actually make more power with Iron heads than with aluminum.
Depending on what your compression ratio is, yes you can.
Youre still better off with aluminum, if nothing else, you'll cut about 30-40lbs off the front of the car.
12-12-2004, 10:24 PM
#12
Le Mans Master
It really depends on your horsepower goals. And goals for the car. Figure out what monster you want then go from there.
MrNuke,
Where did you get those heads/what kind of port work?
MrNuke,
Where did you get those heads/what kind of port work?
12-13-2004, 12:46 AM
#13
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Originally Posted by JAKE
My vote is for aluminum, hands down winner.
Aluiminum heads are:
Lighter, which improves weight distributon and handling,
More easily repaired if damaged,
Allow you to run about one point more in compression ratio without getting into detonation which translates into more HP and TQ and Generally have better ports that flow better
The old theory that iron heads make more power due to better heat retention has been recently put to the back to back dyno tests by one of the mags and found not to be true.
Jake
Aluiminum heads are:
Lighter, which improves weight distributon and handling,
More easily repaired if damaged,
Allow you to run about one point more in compression ratio without getting into detonation which translates into more HP and TQ and Generally have better ports that flow better
The old theory that iron heads make more power due to better heat retention has been recently put to the back to back dyno tests by one of the mags and found not to be true.
Jake
I thought that if you took a 9.0:1 compression motor and switched from iron to aluminum that you'd essentially loose power? Is that not true... what magazine ran that article... I'd like to read that.
12-13-2004, 02:14 PM
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If you had 9.0CR on an iron head, and switched to an aluminum head at the exact same cc size so that your CR stays constant, you'll lose power.
If you went with a smaller cc chamber, so that your CR goes up, you'll gain power. Also if you had high CR to begin with, the aluminum would be better.
In low CR applications, the iron head will do better.
If you went with a smaller cc chamber, so that your CR goes up, you'll gain power. Also if you had high CR to begin with, the aluminum would be better.
In low CR applications, the iron head will do better.
