Originally Posted by
CONSO
As to the SH1- wasp - I recall but cannot find that many years ago [early internet ?] or somewhere there was a ' story ' that the higher power WASP engine at that time was NOT known outside of Military- and not available to ' civilians'
You may be thinking of the engine on the U.S. Army Lockheed X-35 (?) (first pressurised aircraft) which was a turbocharged R-1340-43 but still rated at 550 H.P. , the turbo allowing the rated power to be used to a higher-altitude
The max. power in the Wasp R-1340 range of engines was 600 H.P. up from the normal rating of 550 H.P., except that is, for the Australian Wirraway the licence built Wasp was rated at 650 H.P. driving a three-blade propeller though a reduction gearbox (-G suffix).
For Earhart this 600 H.P. was achieved by the use of 100 Octane for take-off the fuel higher octane number orevention "pre-detonation"or "Knock". According to a contributor to the TiGHAR Forum years ago, the 550 rating was changed to 600 in 1941, probably when 100 Octane became more freely available.
Th next higher rating was with the P & W Hornet R-1690 of 700 H.P. used in the Martin bomber of the mid-30's (B10/B13) this engine eventually achieved 825 H.P.