V12 68hp/l

68 horsepower per litre! Air-cooled? You betcha. As it weighs in at a hefty 87cc in displacement this beauty dishes out a whopping great 6 horsepower.

Hobbyist Ralf Drendel designed it with RC planes in mind, but it's so thirsty he's having second thoughts.

It sounds utterly glorious, and I want one despite the fact that I have no idea what on earth I'd do with it... suggestions anyone?