so which do you guys prefer? any pros and cons? i am thinking about nitrous what should i go with? any help would be greatly appreciated

If you go to aluminum heads you need a different intake as the stock intake won't work. It won't match up to the aluminum heads.

i prefer cast iron. its way more forgiving than alloy. ie-overheating. Ive know guys with aluminum engines that toasted the motor in a few minutes trying to get from traffic lane to berm when they blew a water hose for example.

From a performance point of view her are the facts,at the speed at which we drive 55-75mph the cast iron is better than the aluminum head because it heats up faster and hold the heat for a better burn while the aluminum will outperform the cast iron at higher rpm that is whyon the smaller engines and Japanese one's they are constructed of aluminum.

Considered by itself, the act of using aluminum is for weight savings ONLY. Aluminum heats up faster than iron because it is more conductive and has a lower specific heat. Because it is more conductive, it wicks heat away from the combustion chamber. That's why an aluminum head engine can run higher compression than an iron head engine. The aluminum head engine isn't any more efficient than the iron head engine, it can just run more compression to make up for the heat the aluminum takes out of the combustion chamber.

The above applies to the SAME combustion chamber and port design executed in both aluminum and iron.
From a design standpoint, the nifty cylinder head designs are done in aluminum for weight savings and because it's considered "high tech" and most hot rodders don't know any better.

As for discussion specific to 60 degree V6 heads, the Gen I iron heads (stock Fiero heads) are the worst flowing of the three available. The Gen II aluminum heads are better, but require the intake manifold specific to those heads. That manifold is not compatible with a distributor, as GM went to DIS when they changed the head design. Gen III aluminum heads are better than the Gen II heads, but have another intake setup. I don't know if the Gen II & III intakes are interchangeable, but neither one will bolt up to Fiero heads, and vice versa.

Will is correct except that there is another 60 degree V6 head that's cast iron, but has smaller valves and flow worse (although the design is pretty much the same) than the "HO" cast iron head used on the Fiero 2.8 engines.

The Gen III aluminum heads flow 37% more air than the cast iron heads. The design in the aluminum head for the combustion chamber is different than iron heads. You cannot just take the iron heads off and put aluminum heads on without changing the pistons. The C/R will be way to high.

The lower intake is not interchangable between iron and aluminum. But with more air flow in aluminum heads the lower intake off iron heads like the 2.8 lower intake is to restrictive. It will not let enough air flow to get the full potential usage.

As far as over heating, aluminum or iron if you run out of coolant your in trouble either way more than likely.

Heres a coupl of pics intake side of the heads.

Aluminum GEN III

Cast Iron Heads

If your building a performance engine for the 2.8, 3.1 or 3.4 and your not getting the performance you want well you need to look at the overall setup.

First I would use the Aluminum heads, with a different intake setup.
Second you can't use the Fiero intake and expect any major increase. The Fiero intake isn't design for high performance, you can force feed it to a degree with a turbo or S/C.
Third the Cam, we had a whole discussion on that already.
Fourth the exhaust, I prefer headers, but it's a problem finding someone to make them for you on the aluminum engine. You should use a free flowing muffler or resonater tips. Here in Missouri I have to use a Cat because of emissions.

This is getting long, so I'll stop here but there are many more things. Ignition, piston types, rods, rockers, oil pump, S/C, Turbo, etc.

Earl R.

quote Originally posted by batboy: Will is correct except that there is another 60 degree V6 head that's cast iron, but has smaller valves and flow worse (although the design is pretty much the same) than the "HO" cast iron head used on the Fiero 2.8 engines.

Yeah, but the nasty low output heads all came on carbeurated engines. You actually have to look to run across those. All the fuel injected engines had the HO heads.

All things being equal Iron heads will make more power in a Low compresion engine.

there is one more caveat: according to the chevy power manual, the heads are not interchangeable due to piston design. if you switch from iron to aluminum and vice versa, you have to rip the bottom end out and fix that too.

quote Originally posted by 87FieroGTx: All things being equal Iron heads will make more power in a Low compresion engine.

See what I said above about aluminum stealing heat from the combustion chamber. You have to run higher compression with the aluminum heads to get the same power/efficiency. The nice thing about it is that you CAN run higher compression on the same octane with aluminum heads.

There's also combustion chamber volume to consider. As Scarecrow mentioned, the aluminum heads have smaller chambers than the iron heads. Putting Al heads on an engine with pistons for Fe heads raises the compression ratio to something like 13.7:1. Putting Fe heads on an engine with pistons for Fe heads drops the compression to about 7:1.

quote Originally posted by Will: Yeah, but the nasty low output heads all came on carbeurated engines. You actually have to look to run across those. All the fuel injected engines had the HO heads.

No that is incorrect. The 2.8L with fuel injection used in the Cavalier based cars and Pontiac 6000 based cars in the mid 80's were the small valved heads. Only the Fiero and the F-bodies had the H.O. heads. The H.O. heads were first used on the 1983 F-bodies with TBI injection. I think it was 1988 when the Cavalier based cars had 2.8's with aluminum heads and the next year is when the 2.8's were replaced by the 3.1L engines.

The cast heads can be ported to supply enough flow to match the stock GenII aluminum heads. (about a 18-20% increase) But the GenIII's have 37% flow. Plus both aluminum heads can be ported for more flow.

quote Originally posted by Oreif: No that is incorrect. Only the Fiero and the F-bodies had the H.O. heads.

Sorry - gotta disagree on this one - my '86 S-10 w/2.8 has the HO heads as well. It's Throttle Body Injected (TBI). Same casting numbers, etc. 'Smatter-o-fact, the heads from my S-10 currently reside on my Fiero! I'd done lots of work to them, so figured what the heck - trucks not going anywhere (fried bottom end).

Anyhow - I also think I read somewhere that all FI applications got the HO heads.