would appreciate any ideas....
ive learned that aluminum dissapates heat faster and can somtimes not be as efficient and that it expands more and can cause more wear on the head gasket....but the weigh 50lbs less total.
what do you guys think
Iron will take more of a beating and show precaution to wear...
Aluminum is a very frisky material... It will act like nothing is wrong then completely crack without warning.
Personally, I dont much care. Both heads fail... Most of the good proven aftermarket heads are aluminum... So, I wouldnt say aluminum heads are bad at all. Might as well take the weight savings with ur performance gain too ya know
aluminium will also take more compression then a iron head will because of the fact that it disipates heat quicker. There is an ongoing debate as to which head will make more power. some say alum some say cast. lets say that they both can make the exact same power. 50 lbs off the front of your car is still 50lbs. if you are looking to buy a new set of heads go with aluminium.
Good question. My engine's shortblock was built with the same parts as my brother's except for the camshaft. Mine is one size larger than his (Wolverine solid lifter cam 236 INT/246 EXH @ .50, .512 INT/.536 EXH lift vs. Elgin Pro Stock solid lifter cam 248 INT/258 EXH @ .50, .536 INT/.560 EXH lift.)
His engine has cast iron '69 351W heads that are ported/polished and have larger Chevy 1.94 valves installed. Mine are AFR 185's (58 cc's) that are untouched.
We both use dual quad intake manifolds and twin Edelbrock 500 cfm carbs.
On the dyno, my car (with larger cam and aluminum heads) made 307 rwhp/278 rwt. His car (with smaller cam and iron heads) made 311 rwhp/287 rwt.
The difference doesn't equate too much on the track though as I've run a best of 12.42 @ 109 vs. his 12.49 @ 110.
We're both happy with our combos and I bought the aluminum heads in order to save him the aggrevation of porting and polishing another pair of 351W heads.
An iron head will make more power due to the thermal dynamics of the combustion chamber. There will not be hot and cold spots like aluminum produces. Iron obviously is more forgivable and will take a lot more of a beating.
The number one cause of headgasket failure on an aluminum head is constant expanding and contraction (and notice how much more often it occurs with aluminum-headed engines), it literally wears spots on the gasket itself until it will no longer seal. Mind you overall aluminum will dissipate heat a lot more quickly (can also be a bad thing - previously mentioned), but it can normally allow hotter combustion temps: ie - higher compression. Given the weight savings that aluminum has over the boat of a cousin, iron, it's anyone's take on which makes more power in the long run.
The old racers rule is if you run aluminum heads you'll need to run 1 more point of compression compaired to an iron head. That is with everything being the same. Most of the aluminum heads out are of a better design than the iron heads and therefore out perform the iron designs. As with anything set your budget and buy the best you can afford.
I can personally say that my Performer RPM heads (6025) will take as much abuse as most any other iron head. I blew a 302 a few years ago ~6200. The valve hit the combustion chamber and all I had to do is smooth out the spot with a dremel. I've since had the heads on a 331 and now on my 347.
Iron is a harder metal so it will be easier to crack if it is hit with somethinh (IE piston or valve). That's the same principle behind impact sockets. Ever brake a chromie socket with an impact? The impact sockets are built from a softer metal so it will deform rather than crack.
THe quality of aluminum is also a factor. Take a set of ford 3.8 heads. They are made of uber light weight alumninum. My Edelbrock heads are made from t6 aluminum and are VERY heavy. Were only talking 2-4 lbs less per head vs a set of e7s. The only reason why I'd want to use an iron head is if my class limits me to them. As mentioned the benifits (as far as power) is negligable. You will gain a lot more in driveability (as far as compression).
There are good flowing iron heads like dart but if you can save some weight on an already front heavy vehicle why not?
You may have heard of head gasket life reduced while using aluminum heads. THis is caused because of the difference in expansion rate from iron (block) and aluminum (head). Most any motern gas engine uses aluminum heads without failure. This is done by using TTY or torque and turn bolts. THat way the head slides over the gasket when it expands and contracts. You don't even need that. If you get a quality set of Fel Pro printoseal gaskets you should be fine. You can also get a set of MLS gaskets which will probably never blow. I however feel that regular gaskets act as "fuses".
get a set of e7s and run around with them, was that fun? now if you don't like it the stang don't either, so quit being a selfish bastard and get that poor girl some aluminum heads that is all