Sandblasting?....
Because most of the engine components are made of aluminum, I'd recommend you blast with pecan shells. It's much more expensive because of the cost of the shell verses the cost of a silicone sand grit.
You might think of mechanically cleaning and then using a high price primer and high heat paint. I use Sherwin Williams because they sell a really good marine, 2 part epoxy paint that runs around a $100 bucks a gallon. But for me, it's worth it. Most of my primers (which is the most important coat before a top coat is the "235") .........:cheers: