Max Kallio wrote:
2-stroke diesels need compressed air for starting the engine, so the
turbo (exhaust driven centrifugal supercharger) is out of a guestion
and it produces very little boost at low rpm anyhow.

Modern large 2-stroke Diesels (EMD 710 series for example) have a
mechanical drive to the turbocharger which spins it at low power
settings and it acts as a mechanical blower. As power settings come up
and exhaust volume increases, the turbine takes over and operates the
supercharger. Much more efficient than converting mechanical power to
electrical then back to mechanical again.