Nat gas powered 20kw turbine gen set Jul 14, 2015 20:18:08 GMT -5 Quote Select PostDeselect PostLink to PostBack to Top Post by rythmnbls on Jul 14, 2015 20:18:08 GMT -5 Kamps recommends a grade 12.9 bolt to use as a shaft. has anyone used anything else with success? The GTBA also recommends either a 12.9 class metric bolt or EN24T / 4340 steels for these types of engines.Regards,Steve.