Direct Injection Video

[NewbVetteGuy]

This YouTube video answered so many questions I had and questions I didn't even think to ask about Direct Injection.
https://www.youtube.com/watch?v=VNdYv5ER-fo

Really enjoyed it.

*Fuel distribution charge modes
*throttling of torque by using fuel stratification / ultra lean mixtures to reduce pumping losses (because the throttle can be opened more while still providing reduced torque)
*techniques used to shape the distribution of fuel in the chamber (wall guided, air guided, hybrid wall-air, & spray guided)
*DI injector control strategies

"GDI engines struggle with producing peak power at high engine RPM due to the limited window for introducing fuel to air". -> 6:32 in the video: https://youtu.be/VNdYv5ER-fo?t=392

-This point I didn't understand. GDI injectors seem like they should have NO problem introducing fuel to the air; they have a LONGER window than port injection as they can spray fuel when the intake valve is closed. Why can't they just abandon the ultra lean, ultra late, controlled stratification when peak power at high RPM is required?



Adam

[BLSTIC]

GDI Injectors are still flow and range limited, and they only have the intake and part of the compression stroke to inject fuel, unlike port injectors which can just be always on if there's need. Port injectors don't need to inject through an open valve.

This limited window of fuel flow is also a limited window of evaporation and mixing.

That's one reason why the new M139 Mercedes (100hp per 500cc cylinder, still at sane normal car RPM) uses port and DI, because a DI that still idles isn't big enough (also, you can keep intake valves clean with a port injector)