ENGINE TECHNOLOGIES MADE EASY

HERE IS HOW IT WORKS

DIRECT FUEL INJECTION or DFI
is as the name implies, a process of injecting a fuel charge directly into the combustion chamber. Not to be confused with electronic fuel injection (EFI) or programmed fuel injection into the intake passages of a four stroke.

Up Stroke - Intake and Compression
On the up stroke the top side of the piston is compressing only air in the cylinder. At the same time the bottom side of the piston is pulls more fresh air into the crankcase past a one way reed valve. Near the top of the stroke, the direct injector sprays a plume of fuel directly into the cylinder after the intake and exhaust ports are closed. This is accomplished in several ways depending on the engine manufacturer, all serve the same purpose and have more or less the same components. That fuel/air mixture is ignited by the spark plug. The rapidly burning fuel expands and begins forcing The piston down.

Down Stroke - Power and Exhaust
On The down"power"stroke The piston is forced toward The crankcase. As it continues its downward travel it starts first to uncover The exhaust ports. Exhaust gases begin to rush out of The cylinder. The intake ports then uncover, fresh air compressed on The downstroke is then forced into The cylinder and continues to push The remaining exhaust out of The cylinder. Since there was only air in The crankcase The cylinder is cleaned very effectively and readied for The next injection of fuel.

More on The subject of Direct Injection, Electronic injection as well as an overview of The various systems coming soon. Mastertech will attempt to unravel The claims made by The motor manufacturers. Stay tuned!!

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