I feel like a newbie asking this ? but I honestly want to know, alls I know is that they will save you about 60 pounds, what else? I want to know before I go ahead and spend all this cash for such a little HP gain. Say I have 2 pairs of Identical heads, except the one pair is aluminum, what makes the difference?

 

Reduce weight
Transfer heat from the engine better. Aluminum can transfer heat much better than cast iron.
Reduced heat allows higher compression ratios with lower octane requirements. Usually a full compression point higher.

 

Stephen is right. If you run the aluminum ones you should mill the heads before you put thm on so you can use there ablility to have a higher compression ration on pump gas. I saw on an engine that had iron had9.5:1 compression put on aluminum heads and milled them to 10.3:1 compression and ran the same fuel in it and got extra power!

 

The only thing is, I am goin to be a Nitrous car, so I really shouldnt have to worry about the having High compression, right?

 

aluminum pros:
-lighter
-easier to port
-can run more compression, which in an OPTIMIZED combo can help to make more power.

aluminum cons
-easier to strip holes
-warp easier
-lower thermal efficiency

The last points from both are completely co-dependent. Aluminum heads pull heat from the combustion process away. And if you remember the carnot cycle of heat engines, the only thing you want your heat doing is powering the engine, the rest is loss / inefficiency. Now if you take into account that they are stealing that energy, you can optimize your combo to make power by upping the compression, such that even though the combustion event is less efficient from an absolute standpoint, your power output will still be greater than at a lower compression because it is letting your cam make it's ideal proper peak cylinder pressure in it's powerband.

 

I'm running 10.8:1 on pump gas with iron heads (LT1). I usually crush the same (LT1) engines running beer-can heads, and compensate with a lower coolant temperature. However, they CAN have their benefits if applied correctly (not to mention the weight savings).

If you're planning to buy new heads either way, take a look at aluminum. If you're only planning to replace the L98 irons with L98 aluminums, it probably isn't worth the effort or cost. You'd get far more benefit and HP/$$ by purchasing a die grinder or Roto-Zip tool and some burrs, and porting your iron heads.

 

I've heard aluminum isn't the best for a daily driver. One time overheating and they're done for.

 

also they say aluminum heads can drop about 60 pounds offf your weight. and supposidly every 100# is a .1 sec in teh 1/4 mile. Ihaven't tested it ever, but they say its true.

 

Yeah, that's a general rule of thumb.

 

Warping of aluminum heads is old school. Back in the day when they first came out when we were in diapers they may have warped. The new heads are made alot better and have a ton of extra material so they can stand up to just about any abuse. If they warped on astreet car do you think Chevy would have built the L98 Vette heads/LT1 haeds and the whole engine on the LS-1 out of aluminum?

 

Well say my Irons are Ported to hell, and I have a brand new cooling setup, then Im not really gaining anything, except that I would loose 60 pounds. I dont want to bump my compression up because of the amount of nitrous im sprayin.

 

If you have a good set of heads that are ported good than you are basically just as good with the extra weight.

If you port a set of dogs**t iron heads they aren't gonna be as good as some unported aftermarket aluminums.

 

I asked this on the Poweadder board. Maybe you guys could help me out too.

What Heads are you True Nitrous guys runnin?
Im not asking the guys that are stock with a shot on it, but I want to know the guys that are sprayin over or around 200, I was opting for aluminums, but I think Im gonna go with some Irons, what do you have and what would you recommend?

My setup is a 350, .30 over, TRW forged pistons, balanced lower end, fluid damper. oh ya and DFI.
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