Quote:
Originally Posted by DylanFRS
Some of the posts in this thread seem to be talking about the valve overlap changing for cold startup idle. I was under the impression that the FA20 doesn't have the ability to to change valve timing... Am I missing something?
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Yes.
It has AVCS on intake and exhaust cams. Basically, a hydraulic cam phaser moves the cam centerlines. Intake cam can be advanced from the most retarded position, and exhaust cam can be retarded from the most advanced position. This allows overlap if the cams are phased far enough.
Now, it depends on the grind of the cam. If the intake valve opens at 20 degrees ATDC intake, and exhaust closes at 10 degrees BTDC intake, you need over 30 degrees of intake cam advance to create overlap and backflow into the port.