One example injects a very lean mixture that is NOT stochiometric in fact, so lean as to be nearly impossible to ignite. However, there's even the possibility of multiple injections, perhaps during some part of intake and/or compression stroke. Injection timing is only limited to the injector capability, which can be precisely controlled (as mentioned). There is another advantage in some iterations. The timing and data processing requirements are made trivial with modern computers - this is also true of port injection schemes. Because of reduced detonation (engine knock), engines can be built with a higher compression ratio - improving power output, while using the same octane gasoline.ĭirect injection systems do cost more as the injectors require much higher pressures, and are exposed to the rigors of combustion. By injecting the fuel right before the spark plug fires, you can avoid detonation. To produce more power, the same tactic is used as ultra lean burning, but with a stoichiometric fuel/air mixture. In addition to using less fuel, it keeps the cylinder walls cooler, leading to longer engine life. By injecting the fuel near the spark plug just before it fires, you can have a stoichiometric fuel/air mixture in the center of the cylinder for proper ignition, while there is an ultra lean (very low fuel/air ratio) near the cylinder walls. With direct injection, you can create a stratified charge, where the fuel/air mixture is different depending on location in the cylinder. Port fuel injection engines need to run near stoichiometric fuel/air mixtures (slightly lean is possible), in part because it is difficult to ignite very lean fuel/air mixtures.īy design, port fuel injection creates a homogeneous charge (the fuel/air ratio is the same everywhere in the cylinder when the spark plug fires). Gasoline direct injection can improve both fuel efficiency and power in an engine. The ultimate advantage of GDI is that through this technology everything happening inside the engine can be precisely controlled by the electronics and nothing is left to chances.įor example in mpfi some amount of fuel can be left over inside the injectors though not causing an issue, causes slight variation in every stroke but when you move over to GDI, its like a German train time table. GDI engines are built sturdier compared to MPFI engines and last longer.there are a whole lot of possibilities to explore. Better control of the engine since before GDI it was only possible to manipulate valve timings in real time operation to change the efficiency/power characteristics of the engine, now since you can vary the fuel pressure,amount.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |