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      07-14-2017, 10:17 AM   #324
M.Hagen
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Drives: 2009 E90 M3
Join Date: Oct 2013
Location: Layton, UT

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Quote:
Originally Posted by JsL View Post
Why does boosting in lower rpm have more tendency to knock?
Cylinder filling happens over a longer period of time.

Because of this, if you have high loads (or positive pressure "boost") and aggressive ignition, the opportunity for pre-ignition increases; aka knock.

You can mitigate this by having low ignition targets and/or limit the load potential/boost levels.

At higher RPM, the ICE cycles happen so quickly that there is less likely to be knock with the same load/ignition variables as there is less time spent in the 'sensitive' regions of the compression/ignition cycle.
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