The chainsaws are all air cooled. I just was running no main deck for testing it. A speed 400 motor and prop could draw in air from the gun tubs floor openings and blow the heat out the deckhouse windows.
Engine exhaust goes out the stern model mufflers. Same as the real thing.

I spent a LOT of thought on gas power.

Electric and timing gears with pullies beats anything for easy to run PTB's.