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      03-09-2013, 01:29 PM   #243
BMRLVR
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Originally Posted by bruce.augenstein@comcast. View Post
OK, we're so far down in the weeds now that I am quite sure other readers think we're so anal that we had to've been potty trained at gunpoint.



Think about what you're saying here. Say the cam is advancing, so when that begins, the valve begins opening sooner - but it also closes sooner. Then for each revolution, the valve opens that teensy bit sooner, but also closes that teensy bit sooner - until cam advance stops while the valve is on the lobe. For that single revolution (and only when assuming the valve is riding the lobe at that point), duration fractionally changes.

This hardly counts as a change in duration.
The phaser can advance or retard the cam while on the ramp of the lobe so that can change duration. It is actually very cool to watch camshaft angles via the cam position sensors on an engine with VCT. We had the opportunity to do this in one of my technical training courses in engine control systems!





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Originally Posted by bruce.augenstein@comcast. View Post
Then we're in agreement.

Bruce
For sure!

It is nice to have a conversation/debate with someone who is on the same page! I have thoroughly enjoyed this discussion so far!
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Last edited by BMRLVR; 03-09-2013 at 01:35 PM.
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      03-09-2013, 02:02 PM   #244
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Originally Posted by BMRLVR View Post
The phaser can advance or retard the cam while on the ramp of the lobe so that can change duration. It is actually very cool to watch camshaft angles via the cam position sensors on an engine with VCT. We had the opportunity to do this in one of my technical training courses in engine control systems!
OK, point taken. So for that tiny fraction of a second (while VANOS is on the "step" of a cam adjusment) duration changes.

That hardly counts as a duration change, in the sense that a classic change of duration changes performance at whatever rpm. In that sense, cam phasing has a performance affect, but not the instantaneous affect generated by a permanent change in duration at whatever rpm.

In effect, cam-change "steps" are few and far between, based on the speed at which cam phasing can occur compared with the leisurely climb in rpm.

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      03-09-2013, 09:29 PM   #245
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Ride height as in too low or too high? I personally find it low enough to feel great cornering while still high enough that I'm not constantly scraping.

As for exhaust, I agree you don't hear a lot of exhaust sound, but you get plenty of intake and engine sound any time you're running more than 50% throttle -- which is kind of cool, lets you have a sleeper car when driving calmly and a monster when driving harder. I haven't looked into aftermarket exhausts, but if more exhaust noise would mean hearing less of the sweet intake and engine noise, I'm not sure I'd want that tradeoff.
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