Aluminum head question

[6packCuda]

I was thinking about ordering a set of Edelbrock RPM heads for my Cuda. But recently I read an article that said putting aluminum heads on a low compression engine will actually cost you HP due to lower combustion chamber temp. Because aluminum disipates heat a lot faster that iron. I don't know for sure what compression my 451 has, but I don't think it's very high. I usually run 92 octane gas in it, but a couple times I did run 87 in it with no detonation. So, would I be better off just putting the money into the iron heads I have? 

[Oldschool]

If it was my engine, I would either stick with the iron heads, OR, raise the compression and take advantage of the aluminum ones.  Not sure of your budget and if raising the compretion (I know it's spelled wrong, but I already hit the "post reply" button when I realized it)  lol,  is an alternative.  If it is within your budget and time constraints, go with the higher compression and aluminum heads...  Just my 0.02.......        

[6packCuda]

If it was my engine, I would either stick with the iron heads, OR, raise the compression and take advantage of the aluminum ones.  Not sure of your budget and if raising the compretion (I know it's spelled wrong, but I already hit the "post reply" button when I realized it)  lol,  is an alternative.  If it is within your budget and time constraints, go with the higher compression and aluminum heads...  Just my 0.02.......        

How high should I go with it? This is a street driven car and I want it to run on 92 octane.

[sleepychallenger]

clinging for answers

[MEK-Dangerfield]

How high should I go with it? This is a street driven car and I want it to run on 92 octane.

That's the kicker. I have 10:1 with the old iron heads. With 93 octane, I am border line. I have to watch where I put the timing, or I get pinging under heavy acceleration. You could also go crazy with compression and use an octane booster. It depends on how much you drive it. Here is something Oldschool turned me on to that works a little magic.  

http://www.kemcooil.com/products.php?cId=4



  Mike

[Tubbed440]

What camshaft are you running in the current engine?   This could tell us a whole lot about the amount of compression you would be able to run on pump gas.

[Jacksboys]

What camshaft are you running in the current engine?   This could tell us a whole lot about the amount of compression you would be able to run on pump gas.

[Chryco Psycho]

generally again depending on cam 9.8-10.2 will run on pump gas with Iron heads & with alum & good quench 1 point higher

[6packCuda]

What camshaft are you running in the current engine?   This could tell us a whole lot about the amount of compression you would be able to run on pump gas.

Comp Cams 284/.507

[Tubbed440]

I would definately get the aluminum heads.  I assume you are running an open chamber head now?  Maybe a 906 or something.  If you are, you could get the 88 or 84 cc eddies and if compression is a concern, shave a couple thousandths off to get that combustion chamber down to size.  If you go with the Indy EZ, I think they come standard with 78 or 74 cc combustion chambers.  Remember, both heads are good, but the EZ's have more potential in them than the Eddies....for future builds. 

It sure would be nice to know how far (if at all) the piston is down in the hole of that motor.  If it's a 451, somebody had to build it, and it would be kinda weird if it wasn't zero decked....

EDIT: now that I have re-read your post about 3 times, you're going to pull the heads off anyways, right?  Might as well do a little measuring to see what's going on in that motor while you've got them off....and after that, you can make a better informed decision.  If it were mine, I'd buy the aluminum heads, but not everyone out there is a horsepower junkie like I am...

[Oldschool]

  If it were mine, I'd buy the aluminum heads, but not everyone out there is a horsepower junkie like I am...

I'm with ya there...                  

[6packCuda]

I would definately get the aluminum heads.  I assume you are running an open chamber head now?  Maybe a 906 or something.  If you are, you could get the 88 or 84 cc eddies and if compression is a concern, shave a couple thousandths off to get that combustion chamber down to size.  If you go with the Indy EZ, I think they come standard with 78 or 74 cc combustion chambers.  Remember, both heads are good, but the EZ's have more potential in them than the Eddies....for future builds. 

It sure would be nice to know how far (if at all) the piston is down in the hole of that motor.  If it's a 451, somebody had to build it, and it would be kinda weird if it wasn't zero decked....

EDIT: now that I have re-read your post about 3 times, you're going to pull the heads off anyways, right?  Might as well do a little measuring to see what's going on in that motor while you've got them off....and after that, you can make a better informed decision.  If it were mine, I'd buy the aluminum heads, but not everyone out there is a horsepower junkie like I am...

I've concidered shaving the heads to get the compression up, but have heard a lot of negative comments about doing this in the past. Will everything still line up correctly if I shave off a couple thousanths? If I go with the EZs, would the 74cc chambers raise my compression enough that I wouldn't have to shave them?
You guys are probably getting tired of this subject already, but I really do appreciate your advice.

[v8440]

The thing about milling the heads for compression is you can get compression that way, but if the pistons are 100 thousandths down in the bore you won't have any quench.  Compression without quench is a great way to get detonation.  Like others are saying, pull the heads and see what you have.  Make a decision from that.

[Chryco Psycho]

this is a big part of why I prefer the EZ heads , the smaller chamber will compensate by increasing compression by approx the correct amount to make up the heat loss to the alum heads . IF you shave the eddy heads more than .010you will have to shave either the intake surface or the intake to fit the heads  . I do recommend using the Cometic MLS gaskets with an alum head install or you will be replacing head gaskets approx yearly as the different rates of expansion between alum & iron will tear the fiber composition gaskets

[matt63]

this is a big part of why I prefer the EZ heads , the smaller chamber will compensate by increasing compression by approx the correct amount to make up the heat loss to the alum heads . IF you shave the eddy heads more than .010you will have to shave either the intake surface or the intake to fit the heads  . I do recommend using the Cometic MLS gaskets with an alum head install or you will be replacing head gaskets approx yearly as the different rates of expansion between alum & iron will tear the fiber composition gaskets

Just a note with the MLS gaskets - the surface finish of the heads and block have to be much smoother than with a std gasket which means decking the block and perhaps the heads.