On the other hand of course, you could hie yourself off to B&Q, buy a can of their black BBQ aerosol paint and use that!
If the engine has a rough finish, it might be worthwhile taking a little 280 wet 'n dry to the major surfaces simply for cosmetic effect, but the barbeque paint sticks like a limpet, doesn't flake off AND has the huge advantage of smelling like the old fashioned cellulose paint of yore! Who needs beer to get high?
The beauty of the BBQ paint is that it dries extremely quickly. This means that the engine can be given a quick touch-up on occasion (with a little judicious masking off of non-paintable bits) and, because it's semi-matt (and obviously heatproof) dirt washes off easily.
It's also excellent for brake calipers.