aftermarket CAST IRON heads?
- Thread starter 65notch
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302 coupe
Founding Member
world products/roush, and then you have RHS stuff (formerly known as pro-topline). The RHS sutff can be bought thru Jegs, though they cost $600 more than they did when sold as Pro Toplines. The world/roush heads are ok, particularly if you can do a little home porting on them, in stock as-cast form they leave a bit to be desired. The RHS/PTL heads flow excellent, on par with TFS. I'd go aluminum in a heartbeat, theres no reason not to, plus you rid 50 lbs off the front of the car and you can run about .5 more compression.
Tim65GT
Active Member
Originally posted by 302 coupe:
Agreed. There was a good article in the March issue of Car Craft. Bottom line:
Pay a little more and save the wieght.
Agreed. There was a good article in the March issue of Car Craft. Bottom line:
Pay a little more and save the wieght.
any particular reason you want to stay with iron heads? both will make about the same power out of the box, but as stated you can run more compression with aluminum heads than you can with iron heads. also aluminum heads are easier to repair than iron heads are as you dont need to furnace weld the heads when they crack. the biggest reason to use aluminum heads though is for the weight loss, about 80lbs on a small block.
Route666
Active Member
I'm all for being different, but aluminium heads is one of those areas where there is absolutely no benefit to not going to aluminium, except to have iron for the sake of it being iron.
If you want to retain heat per combustion event, coat some aluminium head combustion faces with ceramic coating, this reduces heat loss and keeps the head cooler, further reducing the possibility of hot spots in the chamber.
This will keep the heat in the combustion chamber, without having the coolant temperature increase.
To go further you would coat the exhaust port with the same coating, and the valve heads (and some of the stem of the exhaust valve). The next step would be to coat the piston crowns.
If you want to retain heat per combustion event, coat some aluminium head combustion faces with ceramic coating, this reduces heat loss and keeps the head cooler, further reducing the possibility of hot spots in the chamber.
This will keep the heat in the combustion chamber, without having the coolant temperature increase.
To go further you would coat the exhaust port with the same coating, and the valve heads (and some of the stem of the exhaust valve). The next step would be to coat the piston crowns.
Hack
15 Year Member
arguments against aluminum heads
I would probably buy aluminum heads over iron heads for a performance application, but I felt that someone should bring up the negatives of aluminum heads.
-the spark plug threads (and other fittings) can strip out and corrode much more easily.
-aluminum is not as stiff as cast iron, so it may not seal as well in blown applications.
- aluminum and iron have different rates of expansion, so heads may not seal to block as well.
-the higher rate of heat conduction in aluminum has some negative effects on power, but that can be compensated for by increasing compression.
I would probably buy aluminum heads over iron heads for a performance application, but I felt that someone should bring up the negatives of aluminum heads.
-the spark plug threads (and other fittings) can strip out and corrode much more easily.
-aluminum is not as stiff as cast iron, so it may not seal as well in blown applications.
- aluminum and iron have different rates of expansion, so heads may not seal to block as well.
-the higher rate of heat conduction in aluminum has some negative effects on power, but that can be compensated for by increasing compression.
Hack said:
as noted there are negatives to aluminum heads, but they can be overcome;
1: helicoil inserts can be installed to prevent aluminum threads from being damaged.
2: aluminum heads are as stiff as iron heads, as long as you dont mill the head surface too much.
3: there are head gaskets that allow for the difference in expansion rates between aluminum and iron.
4: ceramic coatings or higher compression ratios over come the higher heat transfer rate of aluminum.
the cost however is harder to overcome. you can get iron heads for for about $400 less than aluminum heads.
jerry S
New Member
65notch said:
why is retaining heat anything to be desired? I thought one of the benefits of alum is that they don't retain heat.
jerry S
New Member
rbohm said:
or just make sure to install your spark plugs and bolts with plenty of anti-seizing compound the first time around.
jerry S said:
yes, and everytime you install plugs, but the possibility of stripping the thread in the head is still a distinct possibility with aluminum heads. all you need do is overtighten the plugs once or twice and damage the threads.
as far as heat retention, you want to retain heat in the combustion chamber, in order to retain combustion efficiency. aluminum heads allow too much heat to be removed from the chamber. out of the box iron heads will make more power than aluminum heads, assuming the same tune and compression ratio. you can gain that back with aluminum heads with more timing and more compression, and maybe even make more power with aluminum heads, but the cost difference is only worth it if you are racing.
Edbert said:
also...painted them will help retain some of the heat. black being the best color.
after doing all this work to the aluminum heads to make them able to keep more heat in, warpage problems, threads stripping, ceramic coatings, etc... the cost of them would be alot more than a good set of iron heads.
i dont need any fancy aluminum looking heads(infact i would paint them) so the look of cast iron works just fine. it allows for better combustion efficency, cheaper, less warpage problems and im not like everyone else with aluminum heads.
Dunno if this is true, but if you don't keep the correct antifreeze-water ratio it will corode the aluminum really fast. Being in AZ I tend to run more water then is suggested. I also like the nostalgia of cast iron. However i am still on the fence.
Anyone know if there is any truth to the antifreeze mixture problem?
Anyone know if there is any truth to the antifreeze mixture problem?
Route666
Active Member
jerry S said:
It's heat during combustion that you don't want taken away as the same amount of a cooler gas exerts less pressure, thus less power. Aluminium does this. What you don't want is for the head to be hot, and heat air as it is coming in, and perhaps have some hot spots.
65notch said:
Painting them black will help them retain heat? News to me. I suppose that is why radiators are painted black, huh?
Aluminum heads work better and flow better in 99% of the applications. If you want cast iron heads just to be different, suit yourself. Keep in mind that all that a lot of people have been staring under hoods at car shows for about 50 years was cast iron heads, so your not really being a pioneer here.
LMan
Founding Member
65notch said:
..if you want to follow that logic a bit further, I have a 1-barrel Stromberg I'd be happy to sell you for your car
..it would set you apart from the pack, I assure you.
