This is the O.S. Max 18TZ Turbo Engine with Pilot Shaft and 3 needle 11K Slide Valve Carburator. Oversize case fins dissipate heat to keep engine temperatures lower. Five port cylinder liner for increased air flow. 12mm rear bearing lessens vibration and allows engine to handle more torque. Slide valve, three needle 11K carburetor designed for on-road vehicles. Super-hot turbo P3 glow plug for more power and improved fuel economy. Rear exhaust, round port design. Two-piece head design (inner head or head button and outer head)