Direct vs Indirect Fuel Injection?

[Highbeam]

"Cummins are both DI. We always hear how superior the system is, and most don't have glow plugs,"

True, the cummins does not use glow plugs but it does utilize an intake air heater grid powered by electricity. At least in the 5.9 that Dodge uses.

 

[rockyridgefarm]

Most DI's have preheaters... They are much lower maintenence than glow plugs

 

[plaindave]

It's been a few years since I worked for an engine company, but back in my days at Caterpillar we sold both direct injection and precombustion chamber engines. My memory is fuzzy but the precombustion chamber engines offered much lower emissions than DI engines. They were not any where near as fuel efficient, but they were able to burn cleaner. In fact, most engines built for underground mining are of the precombustion chamber type.

The prechamber allowed you to ignite a small, rich fuel mixture which gave you a large flame front to ignite a lean mixture in the main cylinder. Which gave you lower emissions.

But again - my memory on this is fuzzy, I left CAT in 1999.

 

[HGM]

DI vs IDI has nothing to do with glow plugs, although some manufacturers will heat the incoming air instead of the combuston chamber. As far as wich is better, to my knowledge the emissions are better on the DI's, although I dont know that for a fact. The DI's do have more power due to the way fuel is injected into the cylinder, allowing the combustion to hapen in the cylinder rather than be wasted in the pre combustion chamber. The injectors can also be tuned to change efficency, noise and emissions by adding a split shot or pilot injection.Cat also uses the same injection system Ford used on the 7.3L Powerstroke since '94, although they may have used other systems as well. Noise is a big issue now, manufacturers are trying to get the 80"s diesel perception out of the public's mind.