Plus another on that - although it's not my line I've rebuilt a good few engines over the years so I'm genuinely interested.
On edit Please please don't let this thread turn in to an engine building fight as in ''my Harley beats your nascar'' shite.
What if I put a NASCAR engine on my Harley? :P ...or compete in the Sebring 12hr with a v-twin VW beetle?
Bottom line is: listen to the guys that consistently make 100+ hp/liter N/A, and live to tell about it.
My machining birth came in production and got the opportunity to use those machines for parts in off time, as long as I didn't move any work vices etc. When going on my own, the first two items were an auto floor lift and a flow bench, 16yr later and the clients are on national podiums in various road racing circuits.
BMW has been by far, the most stringent OEM engine we have worked with at work. They see a quarter to a million miles and even when totally neglected and/or with power adders, they show ridiculous promise. If you can keep the head down on a turbo engine, the m20b25 is capable if 500whp/tq from a single cam and 2.5l. In 1986 the piston to wall clearance is .02mm on 84mm, and many are well within stock spec this many years later.
400 grit and 25rpm hasn't failed me in the last 18yr of competition, just adjust clearances with bearing size. Don't be afraid to use an oversized/undersized cap-side bearing shell on each journal, even with a main cap straightening.
In all honesty, many people would be quite upset at the carnage upon disassembly of our engines after a season.
