Quote:
Originally Posted by drmiller100
diesels don't have throttle plates, nor throttle plate pumping losses.
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I work at a dealership, although I am not trained as a diesel tech, I do work on the Mercedes OMP 3.0L in the Sprinters and the Cummins engines in Dodge pickups, both of which have throttle plates (electronically controlled, the old 5 cyl inline merc diesel did not.) Also, the lastest VW 16v 2.0 TDI engines have a motorised throttle body and lambda sensors to control egr and air fuel ratio.
Any combustion reaction has a perfect stoichiometric ratio (thermodynamics.) In a diesel there usually is never enough air in the engine to burn all of the fuel that is injected because of design and practical application, however, from my thermodynamics book- diesel will burn in the range of 3:1 all the way to 42:1. This is very different from gasoline which has a perfect ratio of 14.7:1 and will burn from only from about 10:1 to 16:1. The perfect ratio will minimize 5 gas emissions. For example- a gas engine with an afr of 16:1 will produce more NOx gases than one at 14.7:1, an engine with an afr of 10:1 will produce more HC and CO. (see picture) Diesels work the same way, but at different levels/rates but I cannot find a picture.
