Clearly the tanks that used aircooled engines solved the problem; I'm not sure what the full size systems used besides some giant sirrocco fan and efficient ducting. Porsches and VW's solved the problem handily. I was plannig to emulate the clever ducting that Porsche used on the VW and 911 series. I think in my case while the Saito 90TS fit, it was uncomfortably snug not allowing sufficient space for proper ducting. I had planned to use sirrocco fans I had made up specially but when it all came together as a "power pack" it was just too limiting because of its size; due to constraints in the interior of my King Tiger there were only two positions I could install the engine. So I opted for a proven design layout I have and I'm glad I did. The 4 cycles need strict maintenance( valve lash adjustment for one) and after run care, very difficult in a tight compartment. The two strokes don't sound anywhere half as good as a 4 but they are self cooling ( in part), simple, robust and very powerful. High cost of fuel and sound(however this can be mitigated with clever exhaust design) are the main complaints but after a while you grow accustomed. My oldest engine in basically continual service is 32 years old although it is time for an overhaul now...

You gents who have a mind to use a radial can take it on as a challenge. It should prove to be quite the model engineering showcase.

Jerry