GM Heads

[AZ3.8Camaro]

I was looking at a Car Craft magazine, I didn't have time to sit down and read it, but basically the article said that the stock GM steel heads, when ported performed just as well as the aluminum. Of course, there is a weight difference. How much are the stock GM heads for a 3.8? You could always get set of those, get them p&p, if its cheaper, why not. If its not, then never mind, aluminum all the way!

[scottblack]

No necesito aluminum heads..........


Only for hardcore racing and redlining around 7k RPMs.

Read previous posts. :D

Scott

[Dominic]

Correct, Alum heads only perform better above 6,000RPM. The iron heads contain combustion heat better, expand less under high temp and pressure, and actually work better for sub 6,000RPM driving. The only issue with our heads is the square exhaust ports - which basically suck.

Had GM been smart and wanted another 15-20 easy hp in the high end, they wouldve went with round exhaust ports on the heads... :sigh:

[scottblack]

<blockquote>quote:</font><hr>Originally posted by TheCardinal:


Had GM been smart and wanted another 15-20 easy hp in the high end, they wouldve went with round exhaust ports on the heads... :sigh:<hr></blockquote>

Thus this is the reason for porting the heads, correct? Or is it an actual physical impossibility of not being able to round them out?

Scott

[Mike Mayron]

<blockquote>quote:</font><hr>Originally posted by TheCardinal:
The only issue with our heads is the square exhaust ports - which basically suck.

Had GM been smart and wanted another 15-20 easy hp in the high end, they wouldve went with round exhaust ports on the heads... :sigh:<hr></blockquote>

Really? That's the first time I've ever heard that (no scarcasim intended, really). Why is that? I would assume that higher rpms would require more air flow/exhaust and a square has more volume than a circle given roughly the same dimentions right?

1" circle's area is .785 (= 3.14 * .5(.5) )
A 1 x 1 square would be 1

That's over 20% more air/exhaust flow potential in roughly the same size given you could square off a circle evenly, which you normaly can.

Could you explain your reasoning

Unless you're talking about square ports connecting to a round exhaust manifold, then I could see whatca mean. The circle would have to surround the square, and there for it'd have to be smaller than the circle.

[Brian Dieckman]

I've always wondered about this too. Back in the day, when I was doing a flathead build-up, I found some really crazy headers that were actually square at the port. They then slowly tapered to round. The ad said they were supposed to be better, and I bought them, but that was back when I didn't even know about Dynos and stuff. I was just playing. I din't notice any difference when I switched to round headers, so who knows.

Any ideas on this one guys? One I had was that the air passes through a round valve, then gets crammed into a smaller rectangle openening, then back into a round exhaust pipe. (with headers I mean, I'm not sure about the shape of the stock exhaust heads) Air turbulence can wreak havoc on an intake, I wonder if it's so critical with exhaust.

-Brian

[WickEdSix9838]

Your supposed to have an overlap on the roof of the exhaust port, i think its worth power but prob. not enough to matter,

Also, once again, how are aluminum heads only better at 6k-above?? True iron heads will make more horsepower but its not enough to offset the weight difference between iron and aluminum????

Also, just because the exhaust ports are square does not mean they are bad, there a heads out there with square exhaust ports that haul a$$, suck as the Dart 320's and 360's, the shape up inside the port is what matters