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Old 01-25-2012, 06:16 AM   #79 (permalink)
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Originally Posted by oil pan 4 View Post
Anything much leaner than 16:1-17:1 (around where honda lean burn is) burns at a good temperature but doesn't create much power, getting up to speed on the highway, passing and going up mountians could become a problem.
side note: ... 12 year old Honda Insight Lean Burn is significantly above 17:1 ... independently measured peaks at up to 25.8:1 ... and regular operation up to 22:1 is common.

Efficiency is a higher importance to me than Power ... just my personal preference... the Peak Torque or Peak Power Points of the ICE are way down my personal list compared to the Peak Energy Efficiency points.

Loads always vary in the real world ... and their are a number of solutions to that ... over size the engine ... have a more variable engine design so the same engine can choose to sacrifice some engine efficiency for more power when needed ... HEV systems ... etc...

The insight's design is a good example of using multiple approaches to give a variable system that can go from a very efficient cruising condition to trade off some efficiency for more power as needed ... the IMA motor is able to produce ~40% of the system's drive torque under 2,000 RPMs ... AFR varies from as rich as 12.5:1 to 25.8:1 and Ignition timing varying from -20.5 to +46.5 ... V-tech engages and disengages ... etc ... because on the relative flat of the highway running the system like when you need power to climb a mountain is just wasting fuel.

The occasional ICE purge events ( AFR 13.5:1 ) in the Insight while running in LB are to reduce the toxicity of the emissions produced during LB ... has nothing to do with needing more power ... my comment you referenced/quoted was referring to the potential alternative method of dealing with the emission toxicity without leaving the more efficient ICE LB operating condition when conditions do not need the additional power.
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