The engine from Russian car VAZ-21099 Sputnik. semi-accurate to power and sound. runs at sim freq of 2560 Hz (you can...

Simply 40 cc engine i made (powerful). 21 hp, 7 lb-ft. top speed 74 mph on 50 kg vehicle

Single 1.5 cylinder engine 71 hp, 318 lb-ft, low end pc possible, very cool sound

Weird rotor, runs at 5000Hz, torque 274 lb-ft, 77 HP. Top speed 87 Mph FPS Friendly, for low end pc