Thread: VNT Control - Observations for Dawes setup

Originally Posted by jakeslouw

" I think Bush65 put up a diagram of how that needs to be configured."

I think I need that diagram.......

found the diagram, edited my last post to add it.

Yeah, it seems that was nicked from the here:

Manual Boost Controller



More on how NOT to do it and how to correct the mistake:

Dawes & Needle Valve installation gone wrong - Patrol 4x4 - Nissan Patrol Forum

Slug your right about what you said by putting boost to the oppiset side of the vacuum actuator will just push it harder the same way the vacuum is drawing it maby im on the right path using 2 actuators one for vacuum to suck the vanes closed then one for boost to force them open by overcoming the vacuum .
By putting a restriction in the vacuum line IE a valve to regulate the suction and depending on the size of the spring inside the can whit a boost actuator mounted alongside or near enough to get it to push the arm open as boost rises may be the shot tho id say it will take some fine tuning but i think it will work .

Originally Posted by lokka

Slug your right about what you said by putting boost to the oppiset side of the vacuum actuator will just push it harder the same way the vacuum is drawing it maby im on the right path using 2 actuators one for vacuum to suck the vanes closed then one for boost to force them open by overcoming the vacuum .
By putting a restriction in the vacuum line IE a valve to regulate the suction and depending on the size of the spring inside the can whit a boost actuator mounted alongside or near enough to get it to push the arm open as boost rises may be the shot tho id say it will take some fine tuning but i think it will work .

I don't know how sturdy all the linkages on the actuators are but with 15 psi on an actuator which has a diaphragm of 2 inch in diameter will result in about 45 lbs (~20kg) of force, to push against about 20kg will put a bit of strain on your fighting actuators (springs in actuators will take up some of the energy) if they are connected to the same point on your VNT control rod.

I think it could be done through an arrangement of levers but is is all getting a bit complicated with more moving parts than you want.

I had a crack at a diagram

Thats sort of what i was thinking you must have plenty of time to scribble on your computer i need to teach myself how to use a similar cad program so i can do diagrams like that

Ive been doing more reading and i think il go with the dawes valve set up using the vacuum can to pull the vanes shut at idle thwn the boost to open them through the dawes its less complex and now i have more of an understanding on how it works its fairly simple and effective

Lokka, after mucking around with the set up on mike_ie defender, you need to use a needle valve as well to reduce the vacuum as there is way to much. The set up is so simple, just a bit fiddly adjusting the vacuum to suit.

My Dawes valve arrived today so i will be doing this on TD5 with a GT2260V where would one get the damper from? I have what looks like a damper for the wiper lines i got of a P38 wreck. Is it just a non return valve?
Mick

Originally Posted by disco_ute

My Dawes valve arrived today so i will be doing this on TD5 with a GT2260V where would one get the damper from? I have what looks like a damper for the wiper lines i got of a P38 wreck. Is it just a non return valve?
Mick

The so called damper, that is what Nissan call it (that circuit uses the stock Nissan system but with the Dawes valve replacing an ecu controlled valve), can be an orifice fitting (about 0.8 to 1 mm dia orifice). This is where Vern said to use a needle valve, which would be a suitable replacement for an orifice.

It needs to be there to slow/control the rate that vacuum can lower the pressure at the actuator when the Dawes valve is open.