E90Post
 


European Auto Source
 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Questions about VANOS



Reply
 
Thread Tools Search this Thread
      08-24-2009, 10:48 AM   #1
Joshboody
Lieutenant Colonel
25
Rep
1,708
Posts

 
Drives: pickemuptruck
Join Date: Jul 2009
Location: Phoenix, AZ

iTrader: (7)

Questions about VANOS

I did some searches, but not much info. Can someone explain VANOS in more detail?

My understanding:
VANOS is basically a gear system inbetween the crank chain link and camshafts that alters cam timing. Supposedly valves open sooner during midrange rpm. That's all I know... below are my questions.

1. The cam durations stay constant, but open/close either sooner or later correct? It cannot increase/decrease cam durations? Basically the cams are adjusted rotationally and not axially?
2. Is there a direct link between intake and exhaust, meaning both have same timing changes, or can the timing be adjusted independently?
3. Actuated by engine oil in some type of reserve solenoid configuration?
4. During full throttle are there any VANOS activity?
5. Within some threads there are claims that timing is retarded because of VANOS... can this be confirmed? This would be because cylinder pressures increase from intake closing sooner, correct?
6. How do tunes alter VANOS to increase power?

Thanks
Appreciate 0
      08-27-2009, 11:22 AM   #2
Joshboody
Lieutenant Colonel
25
Rep
1,708
Posts

 
Drives: pickemuptruck
Join Date: Jul 2009
Location: Phoenix, AZ

iTrader: (7)

Hoping someone could give some insight into how VANOS works. Or at least let me know if my thinking is close or not. Just curious. Thanks
Appreciate 0
      08-27-2009, 11:39 AM   #3
O-cha
Brigadier General
O-cha's Avatar
81
Rep
4,729
Posts

 
Drives: Mcoupe
Join Date: Oct 2007
Location: In front of you

iTrader: (2)

Send a message via AIM to O-cha
Lift and duration stay the same as that is a function of the cam lobe which cant magically be remachined.

Timing is altered on both intake and exhaust, and independently, in other words overlap can be changed.

It's actuated by very high pressure oil which acts as a hydraulic fluid (from a separate pump in the vanos unit, engine oil pump is not capable of the pressures needed). Their is not a reservoir but there is a pressure accumulator, this is not so much for oil volume but for oil pressure to insure it's always available.

I'll see if I can find a picture of the actual actuator mechanism for gear heads better understanding.

The actual actuation is made by splines in the camshafts and a piston with splines that moves in and out. In simple terms the splines have a curve to them so that when the piston pushes in the camshaft has no choice but to rotate a certain # of degrees. This is where the adjustment comes from.

Yes at full throttle vanos is actuated, that's kind of the point, it's more RPM dependent than anything.

Piggybacks cannot (and/or do not) alter the VANOS timing.

What you said about ignition timing doesn't make much sense, you wouldn't want a situation where cylinder pressure is reduced because of the intake closing later. That would be sub optimal unless your desire was to reduce HP.
__________________
Appreciate 0
      08-27-2009, 02:20 PM   #4
Joshboody
Lieutenant Colonel
25
Rep
1,708
Posts

 
Drives: pickemuptruck
Join Date: Jul 2009
Location: Phoenix, AZ

iTrader: (7)

hey thanks for the info... i picture would be great.

I guess what i was asking about ignition timing is that if intake and exhaust timing changes then cylinder pressure would change and thus timing would have to change. So at full throttle there would be very noticable timing change due to this at certain rpm.

I'm about to get a BT Tool I hope, and would like to run some stock hot/cold weather logs with timing at full throttle, and hope to better understand what i should be seeing. Just want something for comparison if i ever get a tune.

Thanks again.
Appreciate 0
Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 12:57 AM.




e90post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST