S20W Spec Sheet Tapered cone- generator head 11,000 watt continous/13,750 watt surge. 3600rpm 60hz, plain panel with 4 pin electrical connector for a power panel, 120/240 volts. This generator head is made to fit an engine with a tapered shaft 4-11/32" long. Brushless generator design. A 20 hp or more engine is required for full output. Model S20W-130T.