- My model of MX-5 is: __Miyako 2.0 nc2 prht
- I’m based near: __exeter
- I’m looking for technical help or recommendations on: __oil viscosity and VVT
It was suggested today that at least some VVT engines use oil pressure for regulation and that oil viscosity can have an effect on the system.
Can anyone expand on this??
I would have thought that the vvt system only comes into play as revs increase, by which time the oil pressure relief valve will be controlling the oil pressure, (allowing excess pressure generated to return oil to sump) meaning oil viscosity is irrelevant.
It’s usually computer controlled, measuring intake temp, throttle position, engine temp, revs etc to determine the ideal cam timing (intake on a simple system, intake and exhaust on more complex versions)
The cam/s timing is moved via a solenoid and oil pressure.
BMW’s double VANOS also controls valve lift and duration along with timing, which removes the need for a throttle (butterfly valve) in the intake tract.
This is one step away from pneumatic valves, as complete control of start of opening (timing) speed of opening, lift, duration, start and speed of closing, on both intake and exhaust valves is computer controlled. It’s also probably why my last c400hp, 1.6 tonne auto BMW averaged 35mpg !
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