Valvtronic/Double Vanos question

Hi all. I have been driving my 330i manual for a little over a week now. I only have 450 miles on it, so I am taking it easy, observing the 4500 rpm break in limit.

I notice that around 4,000 rpm I feel a surge of power that suggests the valve timing/intake has adjusted for more power. It is similar to the sensation I get when my Honda S2000 hits the Vtec transition point around 6,000 rpm.

I was wondering what, exactly, is happening at this point. Is the surge a result of the valvetronic system increasing lift/duration, or is the double vanos system changing the timing, or is it both?

Also, I was wondering if anyone knows of a publication that has a good discussion of the double vanos and vlavetronic systems and how they work. I read the Car and Driver article that had a couple of paragraphs about it, but I found it very superficial.

Thanks for your comments.

Bill

Reply » Valvtronic/Double Vanos question

Try this: http://www.bmw.ca/technology/tech_fs.asp?lang=en

Reply » Valvtronic/Double Vanos question

Thanks.

Reply » Valvtronic/Double Vanos question

http://www.bmwusa.com/bmwexperience/...gy/Performance

There is a video and some other stuff!
What I think you are feeling is the intake changing its position.

Reply » Valvtronic/Double Vanos question

Like Legal Bill, I also drive a Honda S2000. The Honda VTEC system is essentially binary; at 6000 rpm, a solenoid is actuated which allows oil pressure to move a rod which locks up the cams on the high lift cam follower set. There is a sudden change of engine noise, and a very distinctive surge of power begins. It is not especially refined, but it is very noticeable and exciting. By comparison, one expects the continuously variable VANOS to be quite smooth and refined, more in keeping with the character of a sophisticated sport sedan [vs. the blue collar sports car personality of the S2000]. On our 325i, I do not notice any surge, but then again the 325i has a less aggressive intake system than the 330i, and of course 40 less horsepower.

Reply » Valvtronic/Double Vanos question

Vanos adjustments are smooth and stepless. Inlet manifold has three effective lengths and switches are made abruptly between them at specific revs.

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