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Re: Actually.... (archive)

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Posted by Shawn Fogg on October 24, 2000 at 15:24:33:

In Reply to: Actually.... posted by Mel - Seattle on October 24, 2000 at 14:05:05:

"A truly variable valve timing, like VANOS, is a single cam whose profile can varied throughout the all engine speeds. It is a lot more expensive and complex system than VTEC, but it is more efficinet."

The profile isn't adjusted at all in a VANOS engine. ALL that is altered is the cams timing.

To say that VANOS is better then VTEC because it is continuously variable whereas VTEC only has two positions is wrong. They don't do the same thing.

VANOS in effect rotates the cams a little more ahead or behind based on engine RPM to adjust overlap and such. Kinda like what you can do with adjustable cam sprockets except here it optimzes cam timing through the rev range.

VTEC is very different. At its changeover point it is much more like changing out the camshafts entirely and replacing them with a more aggressive high end cam. When VTEC changes over timing is changed but so is lift and duration. VANOS only does timing.


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