So what's the disadvantage of using these head. Beside there cast iron. I guess they would weigh more. And hold more heat. But what's the advantages. any?

Casting Number 373
Head: 1999-2000 LQ4 6.0 Litre Truck
Material: Cast Iron
Part Number:
12561873
Combustion Chamber Volume: 71.06cc
Compression Ratio: 9.5:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches

 

I have heard that Iron heads are supposed to make more power, but I don't know why or how. Also, they do hold more heat and are more suseptable(sp?) to detonation, thus a neede for a higher octane fuel.

 

Anyone else?

 

Really, Ive always heard just the opposite. Additionally, not many cars even come with cast iron heads anymore, so it can't be because aluminum heads make less power, as all the new engines are making more power than ever.

Aluminum headed engines can usually run a slightly higher compression ratio since the aluminum heads will allow the combustion chamber to run cooler. Some people say that aluminum resists detonation better than cast iron, which only reinforces the first statement.

As for power, aluminum heads are much easier to work with when it comes to porting and polishing.

Weight, lets not forget that using a set of aluminum heads in place of cast iron heads will cut about 50lbs from the front of your car. Moreover, if you have to do engine work that requires head removal, I'll take aluminum anyday of the week.

Durability, it is possible to warp aluminum heads easier than cast iron in extreme overheat conditions, but aluminum heads can be repaired easier than a cast iron. If a cast iron head cracks, they usually end up in the recycle bin, or as door stops.

Drawbacks, spark plugs can get seized into the cylinder head. Certain bolts in or on the aluminum heads can corode, sometimes beyond repair, but this is rare. Practically all aluminum heads have bronze valve guides, whereas cast iron have guide built in. This usually makes the cast iron a work horse for longevity, but I've seen this go both ways for and against.

 

And I could see an advantage if you were draining a 10lbs bottle every 1/4 mile, or was running an ungodly amount of boost. The iorn head would be less likley to lift and blow a head gasket.

 

Cast Iron Heads can generally make more HP. The extra heat they insulate actually has been proven to make more HP. Never heard this about an LS1, yet anyway. Engines are going aluminum for one reason. Lighter! Its definately not because they are cheaper or they can make more horsepower. The only way I think you would be able to tell a difference was on a engine dyno if you are building a serious race engine.

I went with iron heads on my dragster, because alcohol needs the heat. I know its been a while, but sometime back Chevy High Performance had a big article about aluminum vs iron heads. Basically I think the extra weight cancelled out the extra power at the track.

 

How would it work out on a motor producing 15 lbs of boost with the compression being 9.5.1?

 

So how hard is it to port cast iron heads? Almost impossible?

 

considering that is all that was used back in the day I would say negative...

 

but i wouldnt think that many people were porting heads back then

 

Don't kid yourself they were doing it long before we were even born.

 

Its just who still does it? I'm trying to justify using them or not.

 

I've got a set of self hand-ported iron LQ4 heads...yes, they ARE a bitch to port, and yes, they ARE heavy.....but I think that they would hang with ANY set of Stage II aluminum heads, and would be MUCH more reliable in the long run. The only reason I have decided NOT to run them is the weight factor....my truck weighs in at over 5500lbs so anything at all I can do to lower the weight is beneficial to me

 

Exactly as above. They weight a lot more than an aluminum head. They cost more to get ported because it eats the carbide bits like crazy compared to an alum head. Did I mention weight. lol

Cheers.