Head?
Super Moderator
Joined: Apr 2004
Posts: 34,466
Likes: 2,798
More in cases where the aluminum head allows a higher compression ratio. Other variable exist. Are performance heads more likely to be aluminum than iron? All aluminum here:
http://www.edelbrock.com/automotive_...b_victor.shtml
Depends on what else you are doing.
http://www.edelbrock.com/automotive_...b_victor.shtml
Depends on what else you are doing.
Super Moderator
Joined: Apr 2004
Posts: 34,466
Likes: 2,798
Originally Posted by 51dueller
A iron head will make several HP more than the same head cast in aluminum. Not too many manufacturers offer the same head in both styles. RHS is one and they rate the heads the same.
They seem to rate the heads the same. But go to the FAQ:
Their FAQ confirms more CR with aluminum. So, if you want max power, aluminum.
http://www.racingheadservice.com/Inf...adMaterial.asp
What are you basing the "more power with iron" on? (given identical heads and CR etc)??
Last edited by 85e150; Feb 1, 2008 at 07:51 PM.
Trending Topics
Lead Driver
Joined: Aug 2002
Posts: 6,682
Likes: 12
From: Saskatoon SK Canada
Compression ratio doesn't always mean more power. A 429 with 9.0:1 will out run a 7.3L IDI with 20:1 compression. The camshaft dictates what kind of compression you can run with which fuel. Aluminum heads just have a higher resistant to detonation. Look at the old muscle cars, they had iron heads with many of them over 10:1 compression.
If you take any 302/351 with say 9.0:1 compression, the iron head will make like 1-2hp more than the aluminum head. Do the same at 10:1 compression and get the same results but the iron head will need a higher octane fuel.
If you take any 302/351 with say 9.0:1 compression, the iron head will make like 1-2hp more than the aluminum head. Do the same at 10:1 compression and get the same results but the iron head will need a higher octane fuel.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Aluminum offers no more advantage in compression ratio than an iron head. Once the engine reaches operating temps, the head temp is still the same as the iron head. Only way to avoid this is to completely revamp the cooling system to where it could carry off the heat transfered faster. In all engines with std cooling systems, the thermostat regulates the operating temps.
Super Moderator
Joined: Apr 2004
Posts: 34,466
Likes: 2,798
OK, first of all, you can't compare a diesel to a gas when talking compression ratio. Apples and oranges.
Iron (or aluminum) old muscle cars with 12 and 14:1 compression gas motors ran like crap on anything other than 100+ octane and still ate spark plugs like mad.
1 or 2 horsepower is within the margin of error for measurement, I would think.
My original question was on what do you base this? Is there a source that confirms this?
Baddad457 if there is not advantage to aluminum, why does the head maker say there is? Aluminum transfers the heat better and tolerates the higher CR.
Iron (or aluminum) old muscle cars with 12 and 14:1 compression gas motors ran like crap on anything other than 100+ octane and still ate spark plugs like mad.
1 or 2 horsepower is within the margin of error for measurement, I would think.
My original question was on what do you base this? Is there a source that confirms this?
Baddad457 if there is not advantage to aluminum, why does the head maker say there is? Aluminum transfers the heat better and tolerates the higher CR.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Originally Posted by 85e150six4mtod
OK, first of all, you can't compare a diesel to a gas when talking compression ratio. Apples and oranges.
Iron (or aluminum) old muscle cars with 12 and 14:1 compression gas motors ran like crap on anything other than 100+ octane and still ate spark plugs like mad.
1 or 2 horsepower is within the margin of error for measurement, I would think.
My original question was on what do you base this? Is there a source that confirms this?
Baddad457 if there is not advantage to aluminum, why does the head maker say there is? Aluminum transfers the heat better and tolerates the higher CR.
Iron (or aluminum) old muscle cars with 12 and 14:1 compression gas motors ran like crap on anything other than 100+ octane and still ate spark plugs like mad.
1 or 2 horsepower is within the margin of error for measurement, I would think.
My original question was on what do you base this? Is there a source that confirms this?
Baddad457 if there is not advantage to aluminum, why does the head maker say there is? Aluminum transfers the heat better and tolerates the higher CR.
Makes for great advertising 
....................... 
The only advantage to aluminum is the weight factor. I've run both on the same engine and there was no more tolerance to detonation with aluminum. The engine's operating temps didn't change either. I've run a 390 with 10.5 to 1 compression on 89 octane with stock iron heads. My aluminum headed 331 wants only 93 octane fuel with the same compression ratio..............Aluminum has a lesser tolerance to overheating than iron. Therfore, if you're going to use em for towing, you're taking a risk there. You don't see any diesels running aluminum heads.
Cross-Country
Joined: Jul 2007
Posts: 79
Likes: 1
In a world with all things being equall (port flow, compression, valve size, ect) an Iron head will make more horsepower. The internal combustion engine essentually runs and makes its power from heat. Only abt 30 to 40 % of the heat generated is used by the engine. The rest goes out the exause or into the radiator. The better you can "damn" up the heat inside the cumbustion chamber, the more power you can make (that is until things start to melt 
). This is where Aluminum has a slight weakness to cast Iron. Aluminum is a better conductor of heat than Iron is. It will transfer more heat away from the combustion area. Therefore all things being equall you will see a slight loss of power on Aluminum vs Cast Iron heads. This is also why you can generally run 1/2 a point to 1 point more compression with Aluminum heads that with Cast.
In the real world things are never equall and where the aftermarket heads really excell is in port flow. They just are able to get more "Breath" than a stock set of cast iron heads.
). This is where Aluminum has a slight weakness to cast Iron. Aluminum is a better conductor of heat than Iron is. It will transfer more heat away from the combustion area. Therefore all things being equall you will see a slight loss of power on Aluminum vs Cast Iron heads. This is also why you can generally run 1/2 a point to 1 point more compression with Aluminum heads that with Cast. In the real world things are never equall and where the aftermarket heads really excell is in port flow. They just are able to get more "Breath" than a stock set of cast iron heads.