Dawes and Needle Valve?

[Gunner93]

Hey all,

I'm looking at buying an '04 patrol and it has half of the NADS (3" Exhaust, Boost and EGT gauges, and I will be blocking EGR when i get it if not already done) and was just wondering if its worthwhile doing the dawes and needle valve aswell? I understand that it is to control boost and spool up times, but can't boost be controlled by the VNT grub screw?

Any comments/help is greatly appreciated. (:

P.S. Sorry for my lack of knowledge/incompetence haha.
Cheers,
Gunner

[boots]

The grub screw is to limit max boost . When fitting dawes valve , most people plumb it bypassing the vacuum / ecu control solonoid . This makes it full manual control and take it from me , It is so much better once done .Spool up is much smoother this way . well it was for me anyway . mines an 04 aswell .

[threedogs]

As you can see both Boots and myself have 04 models, Boots helped set my DAWES valve, and later I fitted the needle
valve. For any Di Z30 this is the single best mod you can do. As Boots said now you control boost 4x4 runs so much smoother
Cannot recommend enough. Great driving by guages too. Easy mod once you know how.

[Gunner93]

The grub screw is to limit max boost . When fitting dawes valve , most people plumb it bypassing the vacuum / ecu control solonoid . This makes it full manual control and take it from me , It is so much better once done .Spool up is much smoother this way . well it was for me anyway . mines an 04 aswell .

Ok thanks, another (perhaps) stupid question, but when the dawes valve is fitted does that then control max boost?

Cheers
Gunner

[boots]

Yes I never bothered tinkering with the grub screw as it is so difficult to get at . Mine peaks at 17 psi but normal driving hovers at 12-13 psi . before fitting dawes it used to peak at 22psi .Please be mindfull that some engines differ slightly and you have to adjust yours accordingley ,ie- what suits it .

[threedogs]

Yes You take controll of boost as you have now bypassed Vacuum solenoid and ECU

[WYLD333]

Bestest bestest bestest mod ull ever do on the partol, top of everyones to do list

[the evil twin]

Uuummmmm... agree wit the majority but just to clarify a few points...

VNT grub screw adjustment - will control spool up not boost pressure but helps reduce pressure spikes by slowing the spool up as it reduces the amount of angle the actuator can put on the vanes. Us patrollers are stuck with this adjustment option because unlike Skylines, Soarers, WRX's etc we can't easily remap the ECU when we mod other aspects of the engine. Too much adjustment will kill the spool so badly that yes, you won't appear to get max boost and you'll almost think you are in limp mode.

Dawes Valve - will primarily control max boost not spool up as it opens/closes at the set pressure. If you are "factory" and all you are worried about is boost spikes then this is all you need BUT may need to be tweaked to get the correct pressure as some of them out of the box will have too much/not enough spring pressure.

Needle valve - will primarily control spool up as it controls the rate of change of pressure to the actuator. If you have mod'd the exhaust or EGR or whatever and fitted a Dawes then this is very handy for setting up the manual spool rate that best suits your vehicle use.

CRD's seem to be a different animal to the Di's in that as mentioned above the Di's love the Dawes/Needle mods but the CRD's seem to go quite OK with just a minor tweak of the VNT. Dunno why, just the nature of the beast.

Having said the above obviously each item or adjustment will affect other parameters but as a side effect not a primary adjustment.

[boots]

Some word terminoligy differences here . Actuator adjustment shaft is my description of it , but the grub screw would be the limit adjust . This is how I have understood and answered it , so my blew if this is wrong .

[Gunner93]

Uuummmmm... agree wit the majority but just to clarify a few points...

VNT grub screw adjustment - will control spool up not boost pressure but helps reduce pressure spikes by slowing the spool up as it reduces the amount of angle the actuator can put on the vanes. Us patrollers are stuck with this adjustment option because unlike Skylines, Soarers, WRX's etc we can't easily remap the ECU when we mod other aspects of the engine. Too much adjustment will kill the spool so badly that yes, you won't appear to get max boost and you'll almost think you are in limp mode.

Dawes Valve - will primarily control max boost not spool up as it opens/closes at the set pressure. If you are "factory" and all you are worried about is boost spikes then this is all you need BUT may need to be tweaked to get the correct pressure as some of them out of the box will have too much/not enough spring pressure.

Needle valve - will primarily control spool up as it controls the rate of change of pressure to the actuator. If you have mod'd the exhaust or EGR or whatever and fitted a Dawes then this is very handy for setting up the manual spool rate that best suits your vehicle use.

CRD's seem to be a different animal to the Di's in that as mentioned above the Di's love the Dawes/Needle mods but the CRD's seem to go quite OK with just a minor tweak of the VNT. Dunno why, just the nature of the beast.

Having said the above obviously each item or adjustment will affect other parameters but as a side effect not a primary adjustment.

Thanks mate, that helps heaps, have got my head around it and thanks to all that have contributed, will definitely be doing this mod.

Cheers,
Gunner