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Old 04-22-2013, 11:27 PM   #21 (permalink)
Blue Angel
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Join Date: Feb 2013
Location: Ottawa, ON, Canada
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Previous Car - '12 Chevrolet Cruze Eco MT
Team Chevy
90 day: 44.29 mpg (US)

535d XDrive - '16 BMW 535d M-Sport
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Quote:
Originally Posted by Cobb View Post
Good question, depends on where the mpg improvements comes from. Is it less effort for the water pump, power not needed for the electric or mechanical fan, is it allowing more aero mods or is a poorly cooled engine able to maintain and run advance vs retarded timing?
With a diesel there's no timing to worry about. Their claims are based on raising the engine operating temperature to increase combustion efficiency (the hotter the head the less heat wasted), as well as less use of the cooling fans. Heavy trucks have HUGE fans that consume lots of engine power, but this test isolated the fans. The +3% gains reported were from simply operating at higher temperatures.

WRT the water pump, the Evans coolant is actually thicker than a water/glycol mix, so all else being equal it would take more power to turn the pump. This could be part of the -0.26% they recorded while simply adding the Evans coolant without increasing the operating temperatures, though a variance that small could be considered "noise", especially in non-laboratory controlled testing.

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