I am not concerned about the ebay cams other than they imply failures might still be happening. The rough surface means they are not full machined. So they are either cast or forged. Both processes leave the impression of the mold / forge die, typically some what rough. Misspelling on the part label is typical of counterfeit products. I will call GSC and Cosworth and see what they say. Just hate to lose an engine to that sort of failure.

 

There are literally zero camshaft failures still happening. Haven't had failures in years.

 

I'm no metallurgist but AFAIK a billet of cold rolled material would already be better than a forging. More uniform grain structure and less internal stress. Then layer on top of that the precision of machining the part from a billet and you end up with a superior end product.

Again I'm not a metallurgist or a machinist, I'm just a fan of both.

 

I guess people should throw away all those forged cranks and connecting rods, right?

Forging flows the grain structure along the shape of the part. This is like the grain in a baseball bat. Stronger in the desired direction. Biliet lacks those qualities. Biliet is used because small mfg can afford it. They do not have the resources to make a forging. So they claim billet is best for everything. It is not bad but has it good and bad qualities like everything else.

 

I didn't say forgings were bad.

 

^ This

BUT - only if you dont machine them.
Machining forgings make them weaker as you're chopping into the grain structure.
So for cams - it's a moot point as they need to be ground to final shape.

 

like I said, I'm just a fan. I probably shouldn't have crafted my statement to be so absolute. In the end it comes down to what you are trying to make and what process is viable and available to produce that thing. In the context of what is available to us, for our purposes, billet is probably going to be the top shelf.

I wasn't really thinking about forging on the scale of say a 50 ton press but I am willing to admit I am wrong about billet being the best in an absolute sense. The ability to machine a broad range of things from billets is certainly higher then the range of things that can be forged though. A billet is only as good as the process that created it though, obviously starting with a cast billet wouldn't produce as high quality a product as something that was machined from a cold rolled or extruded billet.

Here is a pretty good youtube video I found a while back that gives some good context / history of forging on the kind of scale I think you are getting at. (incase anyone is interested)

 

I am sure you mean well but you are totally wrong, machining changes nothing in the grain structure of a forging. Heat above the re-crystallization temperature would be required to change grain structure. Think orange / yellow heat.

 

I never seen a failure with the GSC cams. And even there are failures with the GSC, keep in mind what share they have in the Evo market. Probably 70-80% of Evo owners have GSC cams at their Evos. I would buy anyday a billet piece instead of a cast one. What is more important regarding cam failures is the installation error. If the cam is not installed correctly it can be broken. I seen some other platforms cutting the cams in half, but this was not a cam error but a builder error.