OSM38157 OS Engines GT15HZ II 15cc Gas Helicopter Engine (Special order, enquire within)OSM38157 OS Engines GT15HZ II 15cc Gas Helicopter Engine The GT15HZ II 15cc gasoline engine with from OS engines comes with a power boost pipe and is designed for 700 size helicopters. Features Large machined cooling head is equipped for better heat dissipation Rear cover find is equipped for better heat dissipation Due to the above, head temperature at spark plug is 15 degrees Celsius lower compare to the previous model GT15HZ Adjustment of Walbro