The Merlin 1D engine! It is able to produce 190,000lbf at sea level with a specific impulse of 282s. It uses liquid oxygen and RP-1 (highly refine kerosene) as it fuel, and 9 of these are used to power the booster. A vacuum variant of this engine with a large engine bell is then used to power the 2nd stage. An amazing engine which is the very workhorse of the commercial rocket sector now.
