Here's the engine for my current project, the Ki-27. It's a 780hp Nakajima Ha-1 Otsu (Type 97) "Kotobuki".
Although this engine was common in the late '30s on Japanese aircraft, it's incredibly hard to find good references for it. The colours are partly guess work as a result, so feel free to comment on them. Detail on the cylinder heads and beyond is limited, as this will be hidden inside the aircraft cowling anyway - and most of this will be pretty much invisible as far as profiles go!