Exhaust gas turbocharged single-acting four-stroke marine engines
can deliver three times or more power than naturally aspirated engines
of the same speed and dimensions. Even higher power output ratios
are achieved on some engine types employing two-stage turbocharging
where turbochargers are arranged in series. At one time almost all
four-stroke engines operated on the pulse system, though constantpressure turbocharging has since become more common as it provides
greater fuel economy while considerably simplifying the arrangement
of exhaust piping.