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Would anyone please compare a stock 633 bottom end with my stock 528i motor? I have a naked 2.8 head that was pressure tested & set aside. Could I install a lil hotter cam with the 3.3 & have a much faster car, or just a lil faster car overall? Then there's gas mileage? Thanx In Advance,,,,Greg

It's a bit faster, but nothing dramatic. There's 2 different 3.3s, the later motronic one from 82-84 having higher compression, 8.8 instead of 8.0:1, but still nothing too dramatic. If you are doing an engine swap for more power, don't even consider anything besides a 3.5, they're cheap, plentiful and never seem to wear out. Or even go to the late 3.5 that came in E32/E34 cars. Mileage will probably drop by one MPG, but not much.