Heads: Aluminum vs Cast [Archive]

Shallow Minded

10-06-2003, 05:45 PM

Starting from scratch on a blown 454 motor for my floating money pit. Have got all winter and want to do it right, but keep getting different stories on aluminum vs. cast iron heads. Obviously, aluminum heads are going to flat-out perform better, but have heard they may not be as durable over time.
For a guy on a budget who doesn't want to pull the motor annually, what should I be looking at? Durability over performance? Or is there that big of a difference? Have at it... Thanks.

GofastRacer

10-06-2003, 07:31 PM

The main difference between aluminum and iron is that the iron heads retain heat(makes more power), the aluminum's dissipate heat, not that they perform better in an equivalent head. The biggest factor is if you run alky, it takes a lot longer to get heat build up with an aluminum head than an iron head,a lot longer than with gas!. Personally, unless I was on weight diet I would run iron heads, besides the corrosion factor is a lot less with iron heads!...Just my worthless .02...... :rolleyes:

O.B eddie

10-06-2003, 07:38 PM

GofastRacer:
The main difference between aluminum and iron is that the iron heads retain heat(makes more power), the aluminum's dissipate heat, not that they perform better in an equivalent head. The biggest factor is if you run alky, it takes a lot longer to get heat build up with an aluminum head than an iron head,a lot longer than with gas!. Personally, unless I was on weight diet I would run iron heads, besides the corrosion factor is a lot less with iron heads!...Just my worthless .02...... :rolleyes: Sooooo Heat = power more like detonation are you serious????????

MikeF

10-06-2003, 07:49 PM

That is "ONLY" if it gets out of control. W/ fuel that burns fast and timing too early, it will happen.
argue

77charger

10-06-2003, 08:13 PM

on a boat your temp is alot lower than a car.So yes detonation is less likely.My choice would be cast.Weight an issue and i had lots of extra money than alm would be the choice.

1FastHallett

10-06-2003, 08:26 PM

i would definatly run cast on a blown motor. will have a much longer life expectancy. and yes heat does = more power to a certain degree. you dont want the motor running to cold or you run the risk of premature wear in the front 2 cylinders because of lack of expansion. if it were me i would run forged pistons, cast large chamber square heads with the blower. if you take the time and put it together right it should last a long time. good luck!!. p.s. if you come across more then one set of large chamber square heads let me know, im looking for a set myself.

victorfb

10-06-2003, 09:08 PM

when you say large chamber "square" heads, what exactly do you mean? are they differant from the large reqtangular port heads? what vehicles came with the square port heads?

wfodude

10-06-2003, 11:25 PM

Well there were a new set of rectangular ports on e-bay..500.00 bare if you want to start from scratch and go that route. I personally use Brodix aluminums. All the previous points are valid but when and if you nuke one, you can weld aluminum easily. I was told by Brodix that they could save just about anything that was short of being blown in half. Bottom line..Less weight = free MPH. Repairability...A big plus. Horsepower?? No question the aluminum heads win this one too...You make your own call But your budget will have an opinion, Brodix are around 2 grand for a set ready to run.

Hotcrusader76

10-06-2003, 11:34 PM

Get a set of 990 cast heads and some forged JE pistons and I'm sure that will keep your wallet on the mild side.

Racing Ray

10-07-2003, 03:41 AM

O.B eddie:
GofastRacer:
The main difference between aluminum and iron is that the iron heads retain heat(makes more power), the aluminum's dissipate heat, not that they perform better in an equivalent head. The biggest factor is if you run alky, it takes a lot longer to get heat build up with an aluminum head than an iron head,a lot longer than with gas!. Personally, unless I was on weight diet I would run iron heads, besides the corrosion factor is a lot less with iron heads!...Just my worthless .02...... :rolleyes: Sooooo Heat = power more like detonation are you serious???????? Yes he is not only serious but correct as well! The power gain of iron is a small one however.
As we always say "weight is horsepower" as well.
Weight is one reason to select aluminum heads. Ease of not only repair but modifying them as well is much easier. I would prefer to port a set of aluminum heads any day over iron. You can taste iron for days after porting a set of them.
I run aluminum heads not only on my race motors but my boat and even my 1 ton Dually.
Aluminum heads will corrode faster but steps can be taken to prevent this as well. In auto you can use a good corrosion inhibiter, this will extend the life tenfold.
In marine use, hard anodizing and sacraficial anodes will take care of the problem. I run one of these as well on my truck engine.
Heat when directed properly can and does make more power if contained in the combustion chamber. Ceramic coatings can easily bring a set of aluminum heads up to par with iron heads in this respect.

flat broke

10-07-2003, 07:08 AM

Hotcrusader76:
Get a set of 990 cast heads and some forged JE pistons and I'm sure that will keep your wallet on the mild side. Scratch the JE's and insert SRPs and your wallet will stay just a tad bit heavier :) They are of equal quality and production techniques, the SRP is justa vanilla version of the JE.
Chris

Dave C

10-07-2003, 02:35 PM

Run a thermostat...... I can get 180 degrees which is nice for aluminum :D

565edge

10-07-2003, 02:44 PM

Srp pistons do not have a full skirt at the bottom.That is one draw back but for a lake boat motor that isnt to drastic they would work better.

gnarley

10-07-2003, 04:01 PM

565edge:
Srp pistons do not have a full skirt at the bottom.That is one draw back but for a lake boat motor that isnt to drastic they would work better. Please define "a lake boat motor" since not everyone may have the same definition or use it the same way that you might.

Dennis Moore

10-07-2003, 04:38 PM

Shallow Minded
There may be some aftermarket aluminum heads that flow better than the standard cast iron rectangle port heads but who cares? When you are running a blower it is pretty much a non-issue. Subtle differences in the intake ports may make a few horsepower difference in a natuarlly aspirated engine but it's pretty much meaningless when you run a supercharger. With boost pushing the air/fuel mixture through the engine, fancy intake ports are a big waste of money(the intake ports just need to be big).
The stock rect.intake port cast iron heads are plenty big for just about any supercharged 454 engine and the quality is very good.
The open combustion chamber heads (most rectangle port heads have the open combustion chambers) work well with flat top pistons on a superchargerd 454.

schiada96

10-07-2003, 05:13 PM

Racing Ray

10-07-2003, 05:23 PM

and removing 85 lbs off the back of your boat won't have any effect anyways..........or will it?

Shallow Minded

10-07-2003, 05:25 PM

So, to summarize, if weight is not an issue (if it was, I'd only pack one cooler :D ), money is, and I'm not going to be running the drag circuit next summer, I should probably just look into a decent pair of iron heads.
Is that a fair assessment?

burbanite

10-07-2003, 06:06 PM

Building a blown, injected alky 496. I bought a set of 188's (the replacement part numbers for the 990's), ported, with flow numbers, 2.25 and 1.88 Ferreas, Isky roller springs, K-Motion Titanium retainers, less than 1200 ft of use for $1000.00.
They will be just fine.

Racing Ray

10-07-2003, 06:44 PM

Pretty much it Shallow.

1FastHallett

10-07-2003, 06:50 PM

i mean 119 cc chamber heads when i say large chamber heads. i was looking at the brodix heads but not sure if i wanna spend the cash. i would also have to buy a new intake since i curently have an oval port victor jr, but im sure i wouldnt have a problem selling or trading it.

GofastRacer

10-07-2003, 08:02 PM

GofastRacer

10-07-2003, 08:03 PM

Racing Ray:
and removing 85 lbs off the back of your boat won't have any effect anyways..........or will it? :D :D

gnarley

10-07-2003, 08:44 PM

Dennis Moore:
Shallow Minded
There may be some aftermarket aluminum heads that flow better than the standard cast iron rectangle port heads but who cares? When you are running a blower it is pretty much a non-issue. Subtle differences in the intake ports may make a few horsepower difference in a natuarlly aspirated engine but it's pretty much meaningless when you run a supercharger. With boost pushing the air/fuel mixture through the engine, fancy intake ports are a big waste of money(the intake ports just need to be big).
The stock rect.intake port cast iron heads are plenty big for just about any supercharged 454 engine and the quality is very good.
The open combustion chamber heads (most rectangle port heads have the open combustion chambers) work well with flat top pistons on a superchargerd 454. Hey Dennis or any of you other guys care to chime in after this go ahead. No one seems to have asked what kind of HP Shallow wants or how fast he wants to go or how many RPM he wants to turn. Wouldn't big CC square port heads be a waste of money if he doesn't plan to turn 6000 or more? Wouldn't a good set of high flowing ovals do real good up to 5500 or 6000? Won't some of the low end be lost or the engine act a bit lazy with square ports & the 177 blower he has at lower RPM? I would agree to big flowing square port heads if he had the right blower on it but he wants to find the right set of heads to work his combo & not over build with the wrong set of heads. I think there is more to building an engine than just slapping on a set of big heads & in this case the right set of heads need to be found for his particular needs & application.
just my .O2

Hotcrusader76

10-07-2003, 09:47 PM

gnarley:
Dennis Moore:
Shallow Minded
There may be some aftermarket aluminum heads that flow better than the standard cast iron rectangle port heads but who cares? When you are running a blower it is pretty much a non-issue. Subtle differences in the intake ports may make a few horsepower difference in a natuarlly aspirated engine but it's pretty much meaningless when you run a supercharger. With boost pushing the air/fuel mixture through the engine, fancy intake ports are a big waste of money(the intake ports just need to be big).
The stock rect.intake port cast iron heads are plenty big for just about any supercharged 454 engine and the quality is very good.
The open combustion chamber heads (most rectangle port heads have the open combustion chambers) work well with flat top pistons on a superchargerd 454. Hey Dennis or any of you other guys care to chime in after this go ahead. No one seems to have asked what kind of HP Shallow wants or how fast he wants to go or how many RPM he wants to turn. Wouldn't big CC square port heads be a waste of money if he doesn't plan to turn 6000 or more? Wouldn't a good set of high flowing ovals do real good up to 5500 or 6000? Won't some of the low end be lost or the engine act a bit lazy with square ports & the 177 blower he has at lower RPM? I would agree to big flowing square port heads if he had the right blower on it but he wants to find the right set of heads to work his combo & not over build with the wrong set of heads. I think there is more to building an engine than just slapping on a set of big heads & in this case the right set of heads need to be found for his particular needs & application.
just my .O2 Very good point Gnarley. A set of 049 with large valves might just cut it for a blown "Lake Boat" motor pushing 5-6lbs boost, no?

565edge

10-07-2003, 11:41 PM

gnarley:
565edge:
Srp pistons do not have a full skirt at the bottom.That is one draw back but for a lake boat motor that isnt to drastic they would work better. Please define "a lake boat motor" since not everyone may have the same definition or use it the same way that you might. I didnt mean to say they would work better but would be o.k. to run.If you were going to have a bunch of cylinder pressure then i would run j/e or something close.

Dennis Moore

10-08-2003, 07:47 AM

You don't need to build port velocity with a supercharger. Small port heads are just a restriction to flow. You are not relying on the cylinder vacuum/high velocity ports/high velocity intake manifold to fill the engine and create a sharp pull on the carburetor venturis.
Bigger is better with a supercharger! If you have lower boost as a result of bigger intake ports this means that the blower doesn't have to work as hard to fill the cylinders and the blower requires less horsepower to operate.
High boost pressure doesn't mean that you are making lots of horsepower, it means that you have a lot of restriction to air/fuel mixture flow with small intake ports and valves. Spinning the blower fast and having low boost pressure means you are really making power!
Dennis Moore

Shallow Minded

10-08-2003, 07:56 AM

Right on, Gnarley. Realistically, I don't want to spin much over 5200 RPM's. Looking for at least 520 HP and the motor is going in my '92, 26 ft. Wellcraft Nova, decent sized powerboat weighing in around 5500 lbs.
That being said, just want a solid, bullet-proof motor that will run and run and run... smile_sp

gnarley

10-08-2003, 09:40 AM

Dennis Moore:
You don't need to build port velocity with a supercharger. Small port heads are just a restriction to flow. You are not relying on the cylinder vacuum/high velocity ports/high velocity intake manifold to fill the engine and create a sharp pull on the carburetor venturis.
Bigger is better with a supercharger! If you have lower boost as a result of bigger intake ports this means that the blower doesn't have to work as hard to fill the cylinders and the blower requires less horsepower to operate.
High boost pressure doesn't mean that you are making lots of horsepower, it means that you have a lot of restriction to air/fuel mixture flow with small intake ports and valves. Spinning the blower fast and having low boost pressure means you are really making power!
Dennis Moore I might be wrong here but a bigger supercharger will fill the ports faster than a smaller one (sarcasm) a small blower will not have the necessary flow at lower RPM to be efficient as the larger one and filling the ports at low RPM. I can state from example that mine has little to no boost pressure below 3000-3500 RPMs or in that range (I forget the exact RPM) and after that boost comes up. So without any additional boost pressure below that RPM isnt it better to still have good port flow without the additional boost? Also Shallows engine is a Gen V & if it has the 177 blower it will also have or should have an oval port manifold.
The real question is what set of heads would compliment a Gen V 454 with an oval port intake (assumed) running 6 pounds boost, a Weiand 177 & turn 5200 RPM? What heads would help him make 520 HP minimum in a 26 foot boat weighing 5500 pounds? Thats his questions.
An additional question is will the factory exhaust be able to handle the increased exhaust flow at 550 HP? Remember he's on a budget, sure some of us can say well just put this on & do that & change that and soon ca-ching your over budget.

Liberator TJ1984

10-08-2003, 09:50 AM

I went with aluminium over cast to save weight and get better performance..my motor is a stock bore 454 ..I put a set of Pro Topline 320's on ..probably a little overkill but they were only $1800 complete set up for roller cam..the heads I had would have cost around 1g to set up..
now if I decide to upgrade lower end ?? say go to a 540 later , heads will still work ,spent a little more now instead of later, and as stated above + if hurt they can be repaired
just my 2*
Gopherrr
if I may add also,
the iron set of heads I had ,I sold for $ 600 with small roller setup. Take this away from the cost of the alum.heads = $ 1200 and I think the deal is way better, I would have spent the diference in porting and valve train and probably not get what i got now
[ October 08, 2003, 01:25 PM: Message edited by: Liberator TJ1984 ]

gnarley

10-08-2003, 11:26 AM

And another thing that hasn't gone back & forth enough is Iron's heat retention which may produce detonation due to the heat, which requires less advance in your timing but heat is power right???
But what about the aspect of aluminum's ability to run a bit cooler & the gain of an additional few degrees in your timing which would also yield more HP??? Aluminum heads have proven themselves in durability & work extremely well as long as you get everything warmed up properly!
What kills engines is NOT getting everything warmed up before you hammer them, including the oil. Too many guys get in a boat and run them for about a minute then idle out of the no wake zone & hammer them with cold oil & wonder what happens when they spit a rod out, hmmm ??? Why do you think there are thermal blankets on the oil tanks on race cars? If you put that much money in an engine why would you abuse it by not letting the oil warm up properly?
The heads being suggested here are for Gen IV's??? What are the appropriate numbers for a Gen V or does anyne build up Gen V's? Shallow asked the question but didn't say which generation engine he had so I have pointed that out, he has a Gen V. Also if you do not know, a Gen IV head MAY fit on a Gen V or VI block if the Gen IV head is cast just right but it may still leak. I know as I tried using a set of 049's on my Gen V & I didn't like the fit of the head gaskets. I ended up just using the factory Gen V heads with a lot of work done to them.
SO does anyone have an idea about which head to use on a gen V block with a little blower & oval ports?
Sure is quiet here???
[ October 09, 2003, 09:20 AM: Message edited by: gnarley ]

FLYTE RISK

10-10-2003, 06:14 PM

Well first of all not to piss any one off But! Flow #s are exactly that, and how much, :D equals efficiancy. How many blown alcohol race boats (not to get off the subject) Run B.A.E heads Hmmm I wonder why? Maybe flow? A good set of ported heads irregardless of induction WILL make a difference!! To say it would not would be the same thing as saying a 671 would flow as well as a 1471, Dart and A.F.R as well as Brodix have C.N.C ported heads which to my understanding for the money you get a very good product. Just my opinion!

FLYTE RISK

10-10-2003, 06:23 PM

Oh b.t.w I have a gen v block with pro 1 heads i run a fel pro 1027 for a 4310 bore. No problems yet 2 years got the motor apart gettin the heads ported.Oh also J.E pistons are a great deal lighter than S.R.P for the same rod length. I love S.R.P But rotating weight is a factor also NOS J.E live longer.. :D

gnarley

10-11-2003, 10:57 AM

FLYTE RISK:
A good set of ported heads irregardless of induction WILL make a difference!! To say it would not would be the same thing as saying a 671 would flow as well as a 1471, Just my opinion! THANK YOU! I always thought flow was flow & the more the better, a blower isn't going to make a poor flowing head flow any better, it just flows more because it's under pressure. What's going to flow more air, a ported head with good flow numbers & a blower or an unported head with poor flow numbers & a blower? I'll take the ported head & blower every time!
[ October 11, 2003, 10:25 PM: Message edited by: gnarley ]

Fiat48

10-15-2003, 09:25 PM

Shallow Minded:
So, to summarize, if weight is not an issue (if it was, I'd only pack one cooler :D ), money is, and I'm not going to be running the drag circuit next summer, I should probably just look into a decent pair of iron heads.
Is that a fair assessment? Well, you certainly got the guys out of hiding! I think you just answered your own question. A decent set of iron heads. The biggest advantage aluminum heads hold for me is they can be welded. It's easy when racing to put a lot of money and time in port work and a head that can be welded certainly means a lot, especially when you have built a 'combination" around the heads. I think a cast iron set of Merlins would be a nice choice for you. Especially since you are not running the drag circuit.

blownmoney

10-17-2003, 08:55 AM

The biggest advantage aluminum heads hold for me is they can be welded. installing em isn't a bad advantage either!! :D
how about the edelbrock performer marine heads?, hard anodized, 1400 complete?, seem to be good bang for the buck?

victorfb

10-20-2003, 09:54 AM

id like to know more about the Edelbrocks aswell. they do seem to be a good deal. has anyone tried them yet?

Fiat48

10-20-2003, 05:45 PM

The Edelbrocks are a nice clean casting and are fine. I have a pair of new bare heads if anybody wants them $1000. I was keeping them for spares, but been on the shelf near 2 years. 11/32 guides.

Racing Ray

10-20-2003, 06:46 PM

I run Edlebrock heads on my boat, my duallie and I bought a set for my sons jetboat my other son runs a set on his and his wifes race cars.
$1400 is NOT a complete head the Marine heads do not come with springs, retainers or locks. They leave this for the builder to decide on based on cam selection.
I have seen on several sets problems in valve guide clearance. If you use them be sure to have a local shop check these clearances. As well one set came in with the surface pretty screwed up on one a .010 cut was needed to clean them up. But for any mild BBC I would personally prefer them over iron heads. Edlebrock is now casting all of Chevrolets heads.
Race heads I prefer Dart the heart shaped combustion chambers promote better valve swirl that aid in better flow.