Fuel Consumption

Just to be clear, this is 20 gph computed using actually measured amounts & timed, not a the results of a computer or meter of some sort. 

Rick,

The O.P. states 20 L per hour not 20 gallons.  So that’s 5.3 gallons an hour which seems appropriate for the carbureted 912.  I think he is trying to tune for a bit lower fuel usage.  

Something is not right.

I have a near new Sonex/Rotax 912uls/Airmaster CS/Whirlwind 3 blade prop.

My whole of sortie (average) fuel consumption, Cruise 130 Knots True/ 5000 engine rpm, is a around 14L/hr (often as low as 13.25L/hr) . I flight plan at 15L/hr.

The above is calculated on actual quantity refilled, to top of tank(s)/Hobbs hrs flown,  not instrument indications.

My last aircraft, ATEC Zephyr/912ULS/Fiti 2 blade, ground adjust prop, delivered 100 knots Indicated at 5200 rpm for an average fuel burn of 13L/hr😈

Europa XS Mono Wheel

I’m flying a Europa XS with the same engine/propeller configuration and normally see 4.4 gph at 5000 rpm at 7000’. I’d say you’re fuel flow calculations aren’t accurate and much of Europa’s published data isn’t either.