Yes, I imagine it would be possible to use caliper paint on the engine block. Be aware that most of the caliper paints that I'm aware of are a two stage epoxy, with about an hour and twenty minutes of "open" time. After that, your $45.00 can of paint is done. You can certainly mix half a batch at a time and get great results. I've also had good success with the POR products, as mentioned elsewhere. I wonder if POR stands for "price on request" here as well? HA! No matter what, cleanliness is the key here. Any loose paint, rust, etc. will make a mess of a tedious job. Send us photos of your finished product!