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Old 04-12-2022, 11:35 PM   #17 (permalink)
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Remember that "efficiency" can mean many different things!

The BSFC graphs show the most efficient way for your engine to make power, not specifically the most efficient way to get from point A to point B!

Generally, we say "80% load" is the most efficient--but most vehicles are accelerating at that load. You really don't want to accelerate continuously from the start of your journey to the end; you have to bleed off lots of speed at the end and you wind up wasting all of that energy! And that ignores the potentially HUGE impact of drag at higher speed.

Pulse-and-glide, or pulse-and-coast, allows you to take advantage of the high-BSFC regions of the graph to gain speed, and then use little or no fuel when coasting to a lower speed.

The upshot is that hitting peak BSFC is the most efficient way to accelerate, but usually not the most efficient way to drive overall. You have to do more stuff than just that.

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