I agree, I brush painted an engine a few years ago, as a 'quickie', and it turned out to be one of the best paint jobs I ever put on an engine. I used POR-15's engine enamel. Takes over an hour to get tacky, several days to dry enough to run the engine, but even the stamped steel parts don't show a single brush mark. $22 for a pint, but that was way more than enough for one engine, and it's held up for years.
Engine kit:
ENGINE PAINTING KIT-POR-15 Inc.
Paint only:
ENGINE ENAMEL-POR-15 Inc.