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Old 11-18-2013, 05:32 PM   #9 (permalink)
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subey - '99 Subaru Impreza Outback Sport

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Originally Posted by MetroMPG View Post
Peak engine efficiency isn't the same as best cruising fuel economy.

Peak efficiency on a BSFC map shows at what load & RPM your engine makes the most power/torque per unit of fuel burned. It's usually when making a lot of power, which is why it's applicable to accelerating and using the pulse & glide technique.

But it's not applicable when cruising in top gear because your power requirement then is a small fraction of power needed for accelerating (or climbing).

So you have to operate the engine outside of the "ideal" BSFC zone.
I get all that. It still doesn't explain DWL. I'm not trying to be annoying, just trying to understand the fundamentals.
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