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Old 11-02-2008, 11:37 PM   #15 (permalink)
ConnClark's Avatar
Join Date: Jun 2008
Location: Richland,WA
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Das Schlepper Frog - '85 Mercedes Benz 300SD
90 day: 23.23 mpg (US)

Gentoo320 - '04 Mercedes C320 4Matic
90 day: 22.44 mpg (US)
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Originally Posted by JQmile View Post
When you drive, make sure not to be under boost at all. If the load is too high (say, accelerating up a hill) then the turbo will start to make boost, and the fueling curve will respond to the rise in boost pressure (add more fuel). This only applies on a turbodiesel of course.
Boost pressure does not increase fuel. It does allow the injection system to inject more fuel if you have the petal floored. A turbocharger does however get its power from the energy not recovered by the piston. You are correct in that trying to drive with a low amount of boost is an indication of the piston extracting as much power as it can. This does not mean that you should try to prevent your turbo from creating boost via modifications. Boost actually increases the efficiency of a diesel engine by promoting more complete combustion and more heat energy going into the working fluid and less heat energy being lost to the engine block.

Originally Posted by Big Dave View Post
I put a free-flowing exhaust (you could drop a Cokr can through it) and a free-flowing warm air intake and it didn't help a bit.

One thing you can do. Put a pyrometer on it and drive to keep EGT under 600 degrees F.
Well as I stated before you shouldn't expect a lot. I also wouldn't expect a lot of improvement from anything on a big pickup truck

Also note that a warm air intake does not make a diesel more efficient. It actually lowers its fuel economy and increase NOx emissions.
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