Quote:
Originally Posted by drmiller100
Diesels do not have pumping losses (no throttle plate restriction).
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That's not entirely true. You are correct that diesels typically don't have throttling losses, however, there still are pumping losses. This includes all the losses associated with getting the air & exhaust through the manifolds & ports. In addition, in a turbodiesel, there are turbo inefficienies that are considered pumping losses as well. In some cases, however, if the turbo is being run in an efficient manner (in the sweet spot of the turbo maps), there are some speeds and loads where the tubo actually results in "positive" pumping work (negative pumping losses). The intake manifold pressure can actually be higher than the exhaust manifold pressure. I imagine this might also be possible on a gasoline turbocharged engine, but that's not really my area.