[chiphead]

I'm considering upgrading my 400 from iron heads to aluminum d-ports. My pistons have a 22 CC dish, so I'd have to use 65CC chambers to get any sort of compression.

Which aluminum D-port head would you guys go with?
Would it make good power at 9.7 compression?
Could the chambers be opened later if I re-used the heads on a future build?

[PAUL K]

I'd go with the Edelbrock d'port aluminum 65 cc head.

[GTO Dan]

I had great results with the KRE Ds at 11to1 running 93 octane pump gas.

But it'll be very challenging getting good results at that compression ratio na with aluminum heads for the money spent regardless of brand. If you are unwilling to get new pistons get yourself a set of ported small chamber cast iron heads. Cheaper and better performance with your shortblock.

[ponjohn]

Originally Posted by GTO Dan

I had great results with the KRE Ds at 11to1 running 93 octane pump gas.

But it'll be very challenging getting good results at that compression ratio na with aluminum heads for the money spent regardless of brand. If you are unwilling to get new pistons get yourself a set of ported small chamber cast iron heads. Cheaper and better performance with your shortblock.

What cam?

[steve25]

If we where comparing Apples to Apples in terms of air flow and port size and chamber shape , then a 8.5 iron head would make equal to a tad more power then a 9.7 comp Aluminum head.

[PAUL K]

Originally Posted by steve25

If we where comparing Apples to Apples in terms of air flow and port size and chamber shape , then a 8.5 iron head would make equal to a tad more power then a 9.7 comp Aluminum head.

Have you done any back to back testing on this theory? I remember several years ago a major magazine tested a SBC on the dyno and didn't find any proof the iron heads made more power than aluminum heads.

[steve25]

Theory you say, may be you could back up your side of the discussion , remember we need Apples to Apples and about the closet we're gonna get that I can figure would be a SBC with tested with a first series Corvette Aluminum head and a iron 292 casting, and even the chambers on these two casting are not 100% the same, but about the closest I can think of.

I am sure you would atleast agree that greater heat retention in the chamber of a iron head makes for greater power as it's expanding heated air that powers the piston down the bore.

[PAUL K]

Originally Posted by steve25

Theory you say, may be you could back up your side of the discussion , remember we need Apples to Apples and about the closet we're gonna get that I can figure would be a SBC with tested with a first series Corvette Aluminum head and a iron 292 casting, and even the chambers on these two casting are not 100% the same, but about the closest I can think of.

I am sure you would atleast agree that greater heat retention in the chamber of a iron head makes for greater power as it's expanding heated air that powers the piston down the bore.

Young Steve25 calm down, I thought you might have some actual data. I was surprised at the magazine dyno test and thought you might have some real world "facts". If I remember correctly they compared Dart aluminum and Dart iron heads. They tried to make it an apples to apples comparison, they used the same CC ports and compared flow numbers. Maybe you only do Pontiac heads and aren't aware that Dart gives you a choice of iron or aluminum for most of the Chevy heads.

[BADDTA]

Buy a set of round ports. Why bother with D ports? Upgrades in the future will get u more than D ports. Let's not go down the road of header swap...

Brian

[PAUL K]

Originally Posted by BADDTA

Buy a set of round ports. Why bother with D ports? Upgrades in the future will get u more than D ports. Let's not go down the road of header swap...

Brian

I couldn't agree more but you'd be suprised how hard it is to convince a fellow to change their headers. You're trying to make power but starting out with a big cork screw in the way.

[Dragncar]

Jim Butler told me years ago, "you cant accelerate a crankshaft with those pinched together center exhausts".