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Unfortunately, Daox's OP "increasing EGR flow for better mileage" is written concerning gas or "petrol" vehicles. Without a gas engine's throttle plate and high vacuum at light load, the diesel is a whole different animal. In post #40 of this thread there is a link to scientific testing of a diesel with varying rates of EGR. To summarize their findings: A diesel engine is most fuel efficient with zero EGR but NOx levels are high due to excess oxygen in the cylinder leading to high temperature combustion. With EGR, power output drops slightly but NOx is greatly reduced. So we diesel owners burn a wee bit more fuel to have less toxic tailpipe emissions.
FWIW, my 04 TDI with 60,000 miles shows almost NO intake or EGR valve clogging. I know this was a problem with earlier VW diesels, hopefully solved now with EGR coolers and low sulphur diesel.
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60 mpg hwy highest, 50+mpg lifetime
TDi=fast frugal fun 
https://ecomodder.com/forum/showthre...tml#post621801
Quote:
Originally Posted by freebeard
The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.
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Last edited by COcyclist; 03-22-2011 at 02:30 PM..
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