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Actually x2.... (archive)

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Posted by Mel - Seattle on October 24, 2000 at 16:47:09:

In Reply to: Re: Actually.... posted by Shawn Fogg on October 24, 2000 at 15:24:33:

You are right, I didn't mean to say that the profile changes on VANOS but I did wanted to present it in simplest terms as possible.

Acutally I am not a fan of either system, what's got me grining is the new variable compression engine from SAAB. I think the future is absolutely there. You can get a small 4 banger 1.8L or so to put out some serios HP, maybe even as much 300+ and have very good low end torque with no turbo lag while at the same time the compressor is pumping some well over 25 psi.

Unofortunately SAAB doesn't make nearly as fun cars as the BMW. Before I bought my MZ3 I really didn't know what I wanted and I went and test drove many different cars, one being the new SAAB 9-3 Vigen. It is fun car but it lacks some serious sportiness and refinment. But that's another story.

"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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