I've never seen an engine painted with bc/cc fail, but I supposed it could happen. I would suspect poor prep more than high heat, in which case any paint system would fail. I've posted this before, but here it is again: engine blocks simply do not get all that hot, and with the exception of the exhaust port area, the paint will have no problem at all with heat. For some reason, everyone thinks their engine gets a bazillion degrees and would melt any paint that isn't certified to withstand extreme temps. Ask yourself this: ever paint an engine with plain old Krylon? We all have and the only thing that causes failure is oil, water and gas leaks that take the non-catalyzed paint off in a hurry. Other wise regular old cheap spray cans work fine. Your engine block is heated by the coolant which is heated to 180-200 or so degrees by combustion and regulated by the thermostat. So how could the block get much hotter than that? True, the headers and exhaust transfer a little heat, but if you think they heat the whole engine to 900+ degrees, think again. As far as how many coats of paint, and what color sealer you should use, just use the same basic techniques you would to paint a car body. The rule of thumb is to use a sealer that's as close as possible to the color your using and use as few coats as will give you complete coverage, typically 2-3 medium coats. Heavy coats cause all kinds of problems like cracking, solvent pop and delamination.