Thread: Engine Braking
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Old 09-29-2012, 09:01 PM   #1 (permalink)
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Engine Braking

Hi. So I was reading the article on wikipedia about engine braking.
First, I had always thought that engine braking was because of the friction to be overcome in the engine, not because of vacuum differences. Is that really the main reason for engine braking/loss?

Two, Wouldn't this mean that an engine that is idling uses a lot of power because the throttle plate is blocking airflow?

Three, how do automatic transmission cars avoid this problem, as autos in gear don't slow down as much without acceleration as manuals. Is this solely because of a lack of a direct connection?

Four, as far as I can tell, diesel engines completely avoid this form of engine braking. Why then are they not more popular and too much more fuel efficient? Is it because of higher compression ratios?

and Five, what effects does this have on hypermiling? It seems to reinforce the info found in BSFC charts and the P&G technique.

If anyone could expound on this subject, it would be highly appreciated. There seems to be almost no information about this on the web.

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