MrPotatoHead wrote: ↑19 Dec 2017, 17:47
godlameroso wrote: ↑19 Dec 2017, 17:36
Yes and no. Billet blocks aren't made like swords, the aluminum isn't folded on itself a few hundred times. A billet is just a block of metal, granted not all aluminum alloys are equal. Like I said, it all depends on material and process being used, and the architecture of the block.
Cheap mass produced engines are built with cost in mind, so block structures reflect this. Thin die cast open deck blocks, heads full of casting marks, slag, thin block casing from cheap aluminum, etc. Using billet let's you rectify these shortcomings, but if all the materials and processes are of higher quality than your than a standard civic, casting is just as good.
I totally agree on cost being the driving factor on production blocks and heads for sure. It's all about saving pennies when you make millions of an engine each year. The OEM machining tolerances leave a lot to be desired as well.
You wouldn't believe some of the loose tolerances on EM engine blocks.
As far as billet blocks go, most are made from 6061-T6, either a rolled billet or in some specific cases a forged billet.
If they have a bedplate that is typically made from 7075 or steel, otherwise they use aluminum or steel main caps.
Higher end billet race blocks will also get an additional heat treat stage curing the machining process to further increase the strength of the block.
I've always found the interesting aspect of a billet engine are adding structural features to the block, like using cooling fins, thicker main girdles, re-worked coolant passages, reworked oil passages to optimize the routing, which can by itself make a big difference as far as friction in the oil pump is concerned. However, it's nothing that can't be done through casting if your materials and processes are up to snuff.
Frankly if you have a good process, casting is every bit as good as raw block machining and pieces can be churned out in half the time.
As far as waste is concerned, I don't think it matters, you collect as many shavings and "wasted" metal as you can and you recycle 95% of what you machine away.