V8 Miniature Engines

They are available from Conley Precision for 5300 $. Some guys in germany built a fully working miniature v12 and a small 14 cylinder radialengine and they have a projectwebsite for the V12 here.
Of course they are not alone: The man behind Weber Precision shows how he built his mini-V8 and explains some technical details like camshaft timings, and someone named “Ken” presents his engineering skills at his site.

Flathead V8
12 Cylinder
14 Cylinder Radial Engine