Caterpillar, Cummins, and many with no name plate. The search phrase is "engines for gas compression". They are generally the size of a small truck and require a much larger truck to move them around.
Robin2:
I always thought 1.2L engines in the USA were just used as starter motors.
The large engines in my example actually have fairly normal starter motors. The engines are "vented" when starting so the starter motor does not have to work very hard. The first ignition does not happen until the crankshaft is up to speed.
Jet engines (Allison) are also used for gas compression. Being near a jet engine running at 10,000+ RPM that is moving very large amounts of compressed natural gas at very close to critical pressure / critical temperature is an interesting experience. Pondering all the possible failures boggles the mind.