Quote:
Originally Posted by Martinjlm
Great points!
Part of the reason for adding port injection is that direct injection at start up generates a lot of hydro-carbons and NOx. Port is less susceptible to NOx. So starting the drive cycle with port injection at low speeds then bringing in DI at higher speeds provides better emissions control.
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Also Fuel coming in over the intake valve from port injection can pull heat off the valve, which can bring cylinder temps down, which can bring overall combustion temps down to reduce NOx.
Dual fuel has more flexibility. If they were to pair them together but run the port injection off the high pressure fuel pump, it would create a better atomization than traditional port injection. But the tight space it will be limited to could end up with the fuel cutting the metal in the intake port.
You could also run a periodic maintain routine to clean the valves of carbon build-up.
Direction injection has the ability to inject raw fuel into the cat in the exhaust stroke to warm it faster or hotter.
I feel one of the best improvements auto makers could do is make wide band sensors smaller, and have one on each exhaust port. I know no two engines are the same so I'm pretty sure no two cylinders are the same. So if you could more accurately control fueling for individual cylinders, the overall efficiency and performance would be better.