This is a really really hard one. Here are two parts of an amazing marine engine I saw the other day. I was a bit gobsmacked. They are part of an exhibit, and so you see cutaway sections.
Apologies for the poor photos, it was gloomy and I only had my phone, which has no flash. The first photo shows a cutaway of the cylinder head and piston. I wouldn’t expect you to recognise the engine so here are some extra clues.
It is a type of semi diesel engine. It has I think three (maybe four) cylinders, and is very very compact. It was produced in a number of versions, the latest one developed 465hp at 1300 rpm and weighed 210lb, (that’s some power to weight ratio!) and it could propel it’s craft (which weighed well over a ton) at a speed of over 40 knots over a range of a few miles.
Rick wouldn’t believe me when I told him such things existed, and he’s an engineer!
I don’t expect details of make and model, but can anyone guess what this engine is for?