Automotive Powerplant Conversions: Caveat Emptor
Editorial
I offer my opinion and experience on the subject of using high performance water-cooled automobile engines in your homebuilt airplane. Although I am not a mechanic, I have flown behind several professionally built and maintained auto conversions. In fact one of those car engines put me into a field and destroyed a beautiful replica mustang. I have also had some close calls testing various auto-derived powerplants, which I believe makes me qualified to speak on the matter.
Disclaimer: There are actually some really viable automotive powerplants for airplanes. Corvair, VW, and sub-2 liter variants, like the Geo Metro and Honda motors. Also, this discussion is limited to 4 stroke only powerplants.
Notice from my disclaimer that most of the engines that seem to work well are not fire-breathing V12 Merlin type engines. Where we get into trouble is when we want to put a 400+hp Chevy Corvette motor in our airplanes and think if we gear it down and derate to 300 hp and there won’t be any issues. That’s not how it works in real life. Not to mention that most folks are bolting these to airplanes with stall speeds that make an engine-out off airport landing dicey at best. Continue reading →