I found some info on the hp question - the 55 was rated at 123hp GROSS @ 3800rpm, 109hp NET @ 3600 ... not sure what changed, but the 56 is rated 140hp gross @ 4200rpm and 123hp net @ 4000rpm, and by 58 [my tag] the net was 125hp @ 4000, 145 gross @ 4200 .... so it looks like the tags were NET hp and the books cite gross hp ..... advertising
gross hp is atmospherically corrected to dry air, 59°F at sea level, and figured with no accessories or exhaust - net is corrected to 32% humidity, 77°F and engine complete as used
Bill
