From Internal Combustion Engine Fundamentals by John Heywood
Consider the Diesel:
At 1800 rpm, 15 KW output, the Diesel pumping is about 0.25 KW. Piston + crank friction is about 2.3 KW. (friction about 10 times pumping)
At 3600 rpm and 20 KW, pumping is about 2 KW and piston + crank is about 5 KW (friction twice pumping)
Also: double the rpm and the pumping goes up by a factor of 10.
-mort