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Old 08-16-2014, 10:20 PM   #25 (permalink)
serialk11r
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Quote:
Originally Posted by matt36415 View Post
I know engines vary ignition timing based on knock sensors, I didnt think they could change the compression ratio though. That would be a good trick if it can.

Is this real or just a mistake?
All engines nowadays have 40+ degrees of adjustment on the cams so you can vary volumetric efficiency by quite a lot, the compression ratio does not change.

However this technique is limited, you cannot dial the intake cam back past a certain point without incurring losses from the piston pulling down against a closed valve. It's highly unlikely that this engine is capable of achieving 50% volumetric efficiency, because its compression ratio is too high to use internal EGR to allow this.
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