MRMRacing
February 19th, 2008, 11:42 PM
"M" Generation double VANOS like the S54 and S50 B32 (not the S52) are also infinitely variable timing for both the intake and exhaust camshafts except their control methods are different. To sustain the more rapid changes of valvetrain timing and greater forced exerted, each camshafts are controlled by 2 hydraulic solenoids (1 inlet pressure and 1 outlet pressure by camshaft) so you end up with 4 solenoid to control. That will require 4 x GPC's on the SM4 (2 for intake, 2 for exhaust) they are PWM by 12v switching and also require the 2 cam inputs. The cam feedback is via 6 teeth wheel on the intake side and 7 teeth on the exhaust side for more accurate monitoring of cam position. The max VANOS spread on the intake side is of 60 degrees and exhaust 40 degrees (crank) so be careful with the initial setup. I attach attach a picture of the base setup for your reference as it might help you get started.
http://www.mrm-racing.se/images/vanos1.gif
Hopefully this will help understand the major controlling differences for the various VANOS systems. They are "normal" hall effect sensors unlike their M52 cousins. You need to modify the cam triggers so they have either 6, 3 or 1 tooth. This simplest is to make them all one tooth and then also share one of the cam signals with the reference signal. The term BMW commonly uses is Single and Double VANOS. Here is a brief overview of what BMW refers to as "Single VANOS" and "Double VANOS". If only the intake valvetrain timing is controlled it is called "Single VANOS" and if the intake AND exhaust valvetrain timing are controlled it is then called "Double VANOS" same rules apply for all BMW engines, straight or V type (you just end up with twice the hardware on a V engine)
Here listed is examples naming Single or Double VANOS for each engine and how many solenoid outputs required on the SM4 to drive them:
6cyl.
M50tu = Single VANOS (on/off) - 1 solenoid I/O
M52 = Single VANOS (on/off) - 1 solenoid I/O
M52tu = Double VANOS (Infinitely variable) - 2 solenoid pwm
M54 = Double VANOS (Infinitely variable) - 2 solenoid pwm
N52 = Double VANOS (Infinitely variable) - 2 solenoid pwm
("M" Engine)
S50 = Single VANOS (Infinitely variable) 1992-1994 not in u.s - 2 solenoid pwm
S50 = Double VANOS (Infinitely variable) 1995-1998 not in u.s - 4 solenoid pwm
S52 = Single VANOS (on/off) 1996-1998 u.s - 1 solenoid I/O
S54 = Double VANOS (Infinitely variable) - 4 solenoid pwm
8cyl.
M62tu = Single VANOS (Infinitely variable) - 2 solenoid pwm
N62 = Double VANOS (Infinitely variable) - 4 solenoid pwm
("M" engine)
S62 = Double VANOS (Infinitely variable) - 8 solenoid pwm + 1 pwm solenoid pressure regulator
S85 = Double VANOS (Infinitely variable) - 4 solenoid pwm + 1 pwm pressure regulator
12cyl.
N73 = Double VANOS (Infinitely variable) - 4 solenoid pwm
Note: The engines starting with an "N" also have valvetronic variable intake valve opening, you would require extra outputs to drive the valvetronic adjusting motors and inputs for valve position feedback. Valve lift can be varied anywhere from 0.3 to 11mm.
The left piston is exhaust, right intake. This position is at idle.
The solenoids are as follow from left to right: -Exhaust Advance
-Exhaust Retard
-Intake Retard
-Intake Advance
Please note prior in this post it is mentioned cam timing spread angles for S54. For your S50B32 it is slightly different: intake 70 - 130, exhaust 76 - 114 degree. http://www.mrm-racing.se/images/vanos2.gif
The diagram was mainly so you could identify the piston position relative to advance & retard. Piston out=advance, piston in=retard. So you are right in saying that this diagram represents exhaust advanced and intake retarded (minimum valve overlap). You are mentioning about rpm criteria to adjust camshafts position: if you observe the current (stock) behavior, it is based on 4 main criteria. Corse adjustment = RPM & throttle position, fine adjustment by intake air & coolant temp. This OEM mapping is not 100% oriented towards performance since it has to perform certain functions like adding a bit more overlap on intake side when under part load and hot engine to allow limited exhaust gas re-flow to act as internal EGR to reduce NOx. I therefore recommend you do not try to emulate too much the stock control strategy if you are trying to map an all-motor vehicle.
Below is for BMW "Dual Vanos"
http://www.mrm-racing.se/images/bmw1.gif
Inlet Cam Retard Solenoid is located on front head, inlet side lower.
Inlet Cam Advance Solenoid is located on front head, inlet side upper.
Exhaust Cam Retard Solenoid is located on front head, exhaust side lower.
Exhaust Cam Advance Solenoid is located on front head, exhaust side upper.
Remove stock connectors on solenoid and replace them with new since stock contains some electronics.
http://www.mrm-racing.se/images/vanos1.gif
Hopefully this will help understand the major controlling differences for the various VANOS systems. They are "normal" hall effect sensors unlike their M52 cousins. You need to modify the cam triggers so they have either 6, 3 or 1 tooth. This simplest is to make them all one tooth and then also share one of the cam signals with the reference signal. The term BMW commonly uses is Single and Double VANOS. Here is a brief overview of what BMW refers to as "Single VANOS" and "Double VANOS". If only the intake valvetrain timing is controlled it is called "Single VANOS" and if the intake AND exhaust valvetrain timing are controlled it is then called "Double VANOS" same rules apply for all BMW engines, straight or V type (you just end up with twice the hardware on a V engine)
Here listed is examples naming Single or Double VANOS for each engine and how many solenoid outputs required on the SM4 to drive them:
6cyl.
M50tu = Single VANOS (on/off) - 1 solenoid I/O
M52 = Single VANOS (on/off) - 1 solenoid I/O
M52tu = Double VANOS (Infinitely variable) - 2 solenoid pwm
M54 = Double VANOS (Infinitely variable) - 2 solenoid pwm
N52 = Double VANOS (Infinitely variable) - 2 solenoid pwm
("M" Engine)
S50 = Single VANOS (Infinitely variable) 1992-1994 not in u.s - 2 solenoid pwm
S50 = Double VANOS (Infinitely variable) 1995-1998 not in u.s - 4 solenoid pwm
S52 = Single VANOS (on/off) 1996-1998 u.s - 1 solenoid I/O
S54 = Double VANOS (Infinitely variable) - 4 solenoid pwm
8cyl.
M62tu = Single VANOS (Infinitely variable) - 2 solenoid pwm
N62 = Double VANOS (Infinitely variable) - 4 solenoid pwm
("M" engine)
S62 = Double VANOS (Infinitely variable) - 8 solenoid pwm + 1 pwm solenoid pressure regulator
S85 = Double VANOS (Infinitely variable) - 4 solenoid pwm + 1 pwm pressure regulator
12cyl.
N73 = Double VANOS (Infinitely variable) - 4 solenoid pwm
Note: The engines starting with an "N" also have valvetronic variable intake valve opening, you would require extra outputs to drive the valvetronic adjusting motors and inputs for valve position feedback. Valve lift can be varied anywhere from 0.3 to 11mm.
The left piston is exhaust, right intake. This position is at idle.
The solenoids are as follow from left to right: -Exhaust Advance
-Exhaust Retard
-Intake Retard
-Intake Advance
Please note prior in this post it is mentioned cam timing spread angles for S54. For your S50B32 it is slightly different: intake 70 - 130, exhaust 76 - 114 degree. http://www.mrm-racing.se/images/vanos2.gif
The diagram was mainly so you could identify the piston position relative to advance & retard. Piston out=advance, piston in=retard. So you are right in saying that this diagram represents exhaust advanced and intake retarded (minimum valve overlap). You are mentioning about rpm criteria to adjust camshafts position: if you observe the current (stock) behavior, it is based on 4 main criteria. Corse adjustment = RPM & throttle position, fine adjustment by intake air & coolant temp. This OEM mapping is not 100% oriented towards performance since it has to perform certain functions like adding a bit more overlap on intake side when under part load and hot engine to allow limited exhaust gas re-flow to act as internal EGR to reduce NOx. I therefore recommend you do not try to emulate too much the stock control strategy if you are trying to map an all-motor vehicle.
Below is for BMW "Dual Vanos"
http://www.mrm-racing.se/images/bmw1.gif
Inlet Cam Retard Solenoid is located on front head, inlet side lower.
Inlet Cam Advance Solenoid is located on front head, inlet side upper.
Exhaust Cam Retard Solenoid is located on front head, exhaust side lower.
Exhaust Cam Advance Solenoid is located on front head, exhaust side upper.
Remove stock connectors on solenoid and replace them with new since stock contains some electronics.