A couple of years ago, there was a midget racer with a Drake water cooled Harley Davidson engine for sale. The car looked really nice but you could barely see the engine. I just noticed, there is another one of these for sale, but this time the car is all apart and the engine is shown very clearly.
The cylinders are completely covered in water jackets with all of the associated plumbing necessary to carry the coolant. You have to wonder, with all of the strict emission controls on engines these days and the difficulties that come with keeping an air cooled engine clean, maybe Harley could just go back to the Drake. Sure would save on engineering costs. ... Only kidding!