01whitez28

My mustang friend was telling me that he wanted to get iron heads for his 5.0 buildup because they make more power. He said that if you take iron heads with the same casting as aluminum, the iron heads would dyno higher on the same engine.

I think he's full of **** on that and I told him he needs to get aluminum heads for his 5.0. What do the experts say?

blk~2000~Z28

Experts say your friend is a dumbass.


Kick him in the nuts the next time you see him, there is really no merit for his argument. Ask him if they are so powerfull why ford and gm use aluminum on there performance engines.

Slowverado

lol at BLK, as soon as i saw the title of this thread my first thought was to type in "kick your friend in the nutts"....hahaha, yeah, beat him with a stick or heavy object of some sort. the experts say, hmmmm, do a search on nascar, or NHRA top fuel, pro stock etc....those are the extremes of their types of engines and ALL....use aluminum heads.

jmX

Quite a few people agree that iron heads will make a tad more power than aluminum. I've not seen it for myself, so I'll just have to take their word for it. I think it has to do with heat transfer.

Nascar, and others may use aluminum for the weight savings on the front of the car, and to keep the center of gravity lower (the heads are pretty high up on the car).

Anyway, the point is, I beleive your friend is correct and his nuts shall go unkicked.

Oh, sloverado, I saw some tan jeep grand cherokee thing on I-35 a few weeks ago with "SLOVERADO" written on the back. I assume that was you headed to the SBSO.

Slowverado

SLOWVERADO, that was me...what were you in man? i didn't try to get ya to race or anything did i? if nascar engine builders thought for an instant of a second that iron heads would make more power they would have them on the cars, those guys spend houndreds of thousands of dollars annualy if not more in head research for just 5 or 6 horsepower...warren johnson has over 5k sets of alum. big block heads he works with porting, flowing etc to get the best 10-20 at a time to use for his pro stock engines. if iron made more power in ANY way i would have to believe the real pros would be using them.

grooves12

You friend is correct... with the SAME casting an Iron head will make SLIGHTLY more power on a DYNO. However, seeking out Iron heads for a performance car is a big waste for two reasons.

1) Generally the best head designs are all cast in Aluminum.
2) The small HP gain you get from the iron heads does NOT compensate for the weight penalty you receive over using aluminum.

jmX

Slow, I was in a pewter transam, between Austin and Waco heading south to Austin. Yall were looking at the car (my GF's) as you went past. No racing was occuring

As for the rest of the stuff, do a little searching and I bet you'll come across tons of places that have discussed this very topic. Having big chunks of iron on a motor are not good for racing, especially when they are 3 feet off the ground. Acceleration is still dependant on weight...however, the question was which makes more power (not which one would make a car go faster), and that would be the iron.

Slowverado

on a case by case basis i guess...i agree about more power...i was definatly thinking about quicker...

if your girlfriend is blonde and was riding in the passenger seat of the TA then i remember seeing her...i was driving....we saw several car loads of girls on 35 south man, it was great. only regret is not driving back up to Austin saturday night for the Ragweed concert.

SilverSurfer

Iron makes more power, because it retains the heat from combustion better. Aluminum is used more in racing because it's easier to port and repair.

racetolive

Aluminum will always win faster heat transfer rember compression casues heat

Silverbird01

Don't aluminum heads resist pinging and detonation better than cast iron? I had read this somewhere but can't remember where. Can anyone else verify this?

99 Black Bird T/A

iTrader: (4)

All things equal the iron head will make a little more power due to retained heat. Since the aluminum head transfers heat quicker and is less prone to retain heat, the aluminum heat will tolerate a little more compression than the iron without detonation. Depending on the head in question usually an aluminum one will tolerate ~1/2 to 1 point more compression than a similar cast iron one will. Amazingly adding this ~ 1/2 to 1 point of compression helps close the gap between what the iron head and the aluminum were making powerwise. This sort of makes sense because in the end it's all heat transfer.

All things equal the cast iron head will make more. With the bump in compression the aluminum head (with everything else equal) will be very close in the typical applicaiton assuming you push both heads as close to the edge as possible without detonation. As mentioned above the weight savings tips the scales toward the aluminum head.

That's my understanding maybe someone else will clarify better.

DaleMX

iTrader: (4)

So an aluminum head with a coated chamber sounds like the best of both worlds as it would retain heat better.

ULTIMATEORANGESS

iTrader: (4)

i read an article in car craft or PHR years ago and a test was done on identical heads that were aluminum and iron heads.


the aluminum heads had better flow.maybe it was this paticuliar head?

MSURacing

iTrader: (1)

ok guys here it is. HEAT IS POWER!!! the more heat you make the more power you make. Saying that, the more heat you retain in the chamber, the more power (work) can be made. DaleMX has it, why not coat the aluminum head to retain the heat. The thing you have to remember when you do this is if you don't go up in octane, there could be major detonation.
Every fuel has its own self igniting point. If you keep the chamber temp below this temp, you will be fine, if not, well uh, you know what happens.
Hope this clearifys things.

1QWIKZ

iTrader: (6)

i thought iron heads made more power because you can run more timing on them.

MSURacing

iTrader: (1)

Usually when two heads are compared, the aluminum head always has a smaller chamber volume to take advantage of the situation.
So in saying an Iron head takes more timing is not true because if a comparision was made where both heads flowed the same amount of air and had the exact same compression ratio, the aluminum head would actually take more timing because it is "sucking" more heat out of the chamber.

IMO, I would always go with the aluminum heads cause of the weight savings. 60 - 80 lbs, on the top of the engine makes for a bad roll center and also just a plain heavier car. I would just add compression to compensate for the heat loss.

Now if you were racing in a class that has a compression ratio limit, that is a different story. Usually when they let you run aluminum heads, they make you add weight. I would find out where they would let you put the weight and make a decision based on that.

I agree with the guys who are saying that the power from the cast is offset by the weight, and that aluminum is used in racing because of the ease of porting and fixing.

SilverSurfer

Take 2 identical heads, one iron one aluminum. 2 identical motors, both running the same compression, timing and neither is detonating. The iron head will make more power. How much, I can't say.

The aluminum head with a coated combustion chamber is the best of all worlds. This is taking into account weight, ease of porting and repair, and it will have better heat retention than bare aluminum. Racers who know which cylinders run leaner and which run richer, will have the chambers on their aluminum heads coated accordingly. If you have one cylinder running leaner, ie: hotter than they don't coat that chamber, and vice versa. That helps them balance out their EGTs, making more power and a happier engine.

stealth

And there's another factor in favor of iron heads: I run 1700 cfm and a 100 shot, and I am currently torquing my 9/16" head studs to 140 lbs., which tends to bow the aluminum LS1 head a bit. If I could find CI heads that flow 320/350 cfm, I would buy them because they are stronger.

pwrtrip75

iTrader: (8)

this is why fords are so fast...LOL. tell the mustang guy steel pistons are better too. HAHA. let me guess... this guy is an engineer at ford? for had the problem circled from the begining.