Virtually all Diesels in vehicles are both turbocharged and have air to air intercoolers, or aftercoolers. Yes they reduce the air intake temperature, but a naturally aspirated engine will still have a cooler air charge coming in. The main way now that engine manufacturers are combating the NOx is to have up to 5 injection events per power cycle. The one big hit that mechanical injection does creates a big spike in combustion temperature causing higher NOx. The multiple smaller hits keeps the combustion temp down and NOx down. The nice sideline of this is that it also quiets the engine down with the old fashioned Diesel knock. Good Luck, TomC
things I wish I understood better -
Cooler air charge in a naturally aspirated diesels does not apply to DD 2-stroke engines because of the Rootes "blower." I keep wondering about replacing the Rootes blower with a twin-screw (whipple) supercharger which supposedly uses less power and heats the air less. Does anybody have info about this ?
as best I can tell, the intricate passages in the DD's unit injectors either do or could accomplish the same thing as the multiple event injectors on newer engines but I have not seen this issue addressed. Any pointers ?
My interest in the above is fuelled by the need to decide exactly what I'm doing building a new engine for the 4104 I rescued.