Gasoline Direct Injection for a Loop-Scavenged Two-Stroke Cycle Engine 871690
A jerk-pump and poppet injection nozzles for direct gasoline injection were installed onto a Schnurle scavenged spark ignition engine with crankcase compression. The horsepower of the injection engine was nearly the same as that of the carburetor engine, while the BSFC was reduced by 25 to 45% and the exhaust HC emission was so reduced that it became closer to that of a four-stroke engine at medium to high loads, where other specifications of the engine were kept the same as the carburetor engine. At low loads, however, the HC emission did not improve due to misfiring. When the specifications were modified to make use of features of injection engines, the horsepower increased by twofold, and the BSFC dropped by 30%.
According to studies done on MBT injection timing, the vaporization characteristics of a single gasoline droplet was found to be similar to that for the entire spray.