Recently, the addition of direct injection and some
refinement of the crank case scavenging with reed
valves and lamellar intake plus precise lubrication
have produced more fuel ecient and less polluting
builds in outboard and snowmobile applications,
such as Yamaha HPDI [1] or Bombardier E-TEC [2,
3], meeting emission requirements and delivering acceptable
fuel economy in the engine’s most commonly
used rpm range.