How efficient is the 4 stroke engine?

typical efficiency is about 270g/kw/h=201g/hp/h=0.443 lb/hp/h norm is less at higher power levels (higher RPM) sfc figures are less at 400 g/kw/h=298g/hp/h=0.658Ib/hp/h are norm. a good fuel effecient carburettored 4 stroke engine consumes 200g/h/hp/h divided by 740g/l =0.270L/hp/h =0.701 us gal/hp/h for example an engine that produces 60 hp constantly presuming at point of most efficiency than fuel consumption would be 60hp x 0.270 liter/hp/h =16.2 liters/hours or 60 hp x 0.071 us gal/hp/h = 4.3 us gal/hour 26.4 lb/hp/hr