Billet Aluminum Hemi Heads for SB Ford & SB Chevy

[Big-Foot]

Originally Posted by Al Wohlstrom

Stronger, lighter, no structural flaws

I agree with the first and third premises but disagree with the second.

Billet aluminum is far more dense than your typical casting..

[Steve Briscoe]

Originally Posted by Al Wohlstrom

The chamber size is about 52cc. depending of what valves are used. The valves on the current configuration are 2.250 intake and 1.625 exhaust.
The flows are slightly over 400 cfm on the intake and nearly 290 on the exhaust.

Al-
What are the intake and exhaust runner volumes? What was the lift when the heads flowed at about 400cfm?

Thanks!

[Al Wohlstrom]

I stand corrected, the cast heads are lighter. This is a quote from a email from Chuck (the head builder), I hope this answers some questions.

Cast material, per unit of measure is lighter than wrought (billet). The amount is very minimal, however the difference in strength is alot. The advantage of billet is I can use less material to achieve the same strength part. Billet (wrought) material is cast material that has been post cast worked. It can be rolled, forged and stretched. All of these methods take the cast material which is made up of small pieces that are somewhat melted together and stretches or pushes or pulls the pieces into a grain like structure, removing the voids between pieces. It is much like the strength of fresh sawn lumber versus particle board.

Another advantage is wrought material is much more weldable. Should a cast head need to be welded, it often contains contaminates and yields a pitted surface that only gets more contamination from use. 6061 is considered the most weldable of the Aluminum groups.

A third advantage is I don't need to make patterns and cores for every single modification. I just machine the piece differently.

A fourth advantage is virgin A356 cast aluminum has a large amount of silicon in it. It is very abrasive. The life of cutting tools is dramatically reduced while machining heat treated cast aluminum. I have machined hundreds of cast heads over the years and I don't like the result. It is also difficult to achieve the finish on a casting that billet material yields with ease.

On a final note, wrought material being more dense, transfers heat more efficiently than cast.

I have been fussing with port configurations and have settled on a slightly lower flow at .700 lift, 388 cfm v/s 400 cfm (only 12 cfm different), but the low valve lift numbers are incredible with velocity numbers that are unbelievable! These ports are flowing 288 cfm at .400 lift! I went to a friends shop in Phoenix to verify the flow numbers. Mike Zimmerman of Zimmerman Racing Engines did an independent test and got the same results. He is just as excited as I am. I am preparing a Fox Body Mustang to do the street testing. My fingers are crossed but the data says I don't need to.

[flatrod]

Any idea on price on the whole set up heads valve train and valve covers. What about intakes? Is there one for the heads?

[Al Wohlstrom]

He's working on pricing and will have something soon. The manifold will be a 3 piece for injection (2 runners and a valley plate). He has a carb manifold he fabricated on his race car.

[Jeff]

Very interesting, cant wait to hear more!