I see adverts for billet heads and find it hard to imagine that machine tolls can reach all the nooks and crannies necessary to make an efficient working head. Can anyone explain this to me? And to what extent are they a performace item, and to what extent they're for show?
Multi-axis CNC can reach some pretty tricky nooks and crannies and has been doing port jobs for a while. I'd imagine casting is actually more geometry-limited compared to a 5-axis.
Keep in mind that billet heads are also a lower cost option to tool up than a casting, and when you are getting out at the pointy end of the stick, tooling cost plays a real role in taking something to market.
They also let you try a bunch of iterations without having to make pattern and core box changes.
Billets are going to be more sound, with less voids and discontinuities than castings just by nature of the process, so thats nice too.
I honestly can't see how the cooling passenges can be machined. Combustion chamber, easy. Ports- harder but doable. Cooling? How do you get a cutting tool through tiny holes to take that much out?
3D printing seems more likely. But even then, 3D printing the casting cores would probably be the path.
If this is about cutting a head from a solid billet, I can't imagine the cost- it would be days of CNC cutting to do it.
In reply to 93gsxturbo :
Having been involved in both making parts from billet and sand casting, the tool up cost of a billet is way higher.
A sandcast mold is cheap. The tooling alone of a multiaxis machine will be more expensive than the mold.
Yeah, it seems to me that the most efficient way to make a high-performance custom head would be with 3d additive printing followed by machining. I don't get how they can make a decent head starting with a big hunk of aluminum.
In reply to Slippery :
But that tooling is not design-specific. You can tweak the design using ones and zeros but recycle the fixturing for the most part. A casting redesign is more involved *once you get rolling*. Castable aluminum is also a different class of alloys than billet, so, in addition to nearly no voids, the metal itself is better.
Depending on the make and model billet heads are often intended to run only 1/4 mile at a time, so cooling isn't as important.
Kreb (Forum Supporter) said:Yeah, it seems to me that the most efficient way to make a high-performance custom head would be with 3d additive printing followed by machining. I don't get how they can make a decent head starting with a big hunk of aluminum.
Actually, I would think 3D print the core and cast it would be better. 3D printing metal is still pretty slow in the precision you want to have as little post machining you want.
Given the plethora of really good high performance heads out there, getting really high quality casting isn't that hard.
You'll need to log in to post.
