Dawes and Needle valve

Hi all, just a quick note to tell you I have finally got around to having the Dawes and Needle valves fitted. Have kept stock boost level (15psi) which my stock patrol would only ever reach 14 no matter what the revs ?? The needle valve has been set to give a slightly quicker boost actuation. What a difference .. much smoother/powerful at lower RPM and more power on hilly sections where I live. Egt is fine as well .... to all those who havent done this mod yet (or am I the last), then I do encourage you to get it done. Had mine done at Southwest Mechanical and Offroad, Bunbury WA ...

This needs to be done to all modern diesels not just Patrols. I sold 100’s of kits to workshops and owners of Tritons, Navaras, Hilux’s etc etc. Anything with a variable vane turbo needs this mod in my opinion. Letting the ECU decided on boost pressures is just asking for trouble.


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I was a bit shocked at how effective it is to be honest .. and my max was 14 but that extra 1psi makes a heck of a lot of difference. The quicker response at lower rpm is a godsend in traffic too .. very happy😁👍🏻

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Originally Posted by timbo2410

I was a bit shocked at how effective it is to be honest .. and my max was 14 but that extra 1psi makes a heck of a lot of difference. The quicker response at lower rpm is a godsend in traffic too .. very happy[emoji16][emoji1303]

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When I had the old ZD it was running 25psi and that was really good. Drove fantastic.


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Why the dinosaur engine conversion then Mark Mate? Did it go pop or you just needed more low down slow slug clutch saving torque like us family needed too?


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Originally Posted by MB

Why the dinosaur engine conversion then Mark Mate? Did it go pop or you just needed more low down slow slug clutch saving torque like us family needed too?


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The injector pump died on the ZD, I wasn’t prepared to spend a cent more on this donk. Hence the TD conversion. After the conversion was done we stripped the ZD and number 4 piston was cracked anyway so it was just a matter of time...


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We too truly loved our zippy as all get up 2002 ZD, albeit bog stock OEM Mate!
It’s only two downfalls for us found were clutch shagging potential predicted hauling Nags through the slow welfare careful hill starts. Second was a piss poor OEM intercooler strength design which kept hissy fitting with a shipload less than 25psi shoved through her [emoji51]


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Can the Dawes valve be used on petrol engines with variable vane turbo??

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Originally Posted by timbo2410

Can the Dawes valve be used on petrol engines with variable vane turbo??

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If the turbo is controlled using vacuum and not boost pressure. I can’t see why not.


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Bought a 2004 GU secondhand, installed some extra gauges, I was getting 7psi max boost and EGT were often over 500, sometimes over 600
Fitted dawes valve myself, set it to 14psi and now, way more power and EGT sit around 300 cruising 400 working, and 500 with a thrashing, way better.
I think the computer was no longer controlling the turbo as it should have, and was on its way to [grenade ], hence previous owner sold it.

I have mine set at 15psi max. Its a lot more progressive power than before. A lot better at lower rpm and a lot more usable in traffic. EGT's have gone up slightly at lower RPM (i have a 3inch exhaust as well) .. but pretty similar to yours. Around 280 around town and about 470 at 110 with a strong headwind. Thumbs up all round :-)

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Originally Posted by Dagwill

Bought a 2004 GU secondhand, installed some extra gauges, I was getting 7psi max boost and EGT were often over 500, sometimes over 600
Fitted dawes valve myself, set it to 14psi and now, way more power and EGT sit around 300 cruising 400 working, and 500 with a thrashing, way better.
I think the computer was no longer controlling the turbo as it should have, and was on its way to [grenade ], hence previous owner sold it.

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Yeah they work well when tuned right. I had my old ZD at 25psi max and 18psi cruise level and she flew. The ECU really does a shit job of controlling the boost levels.

How long did she last at that pressure

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Originally Posted by timbo2410

How long did she last at that pressure

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Had it at this for two years, then the injector pump died and I wasn't prepared to spent 4-5k on a new pump, so out the ZD came... 25 psi is about the max the turbo can handle, bloody hell did it go though.

Haha i bet it did. One psi higher on mine was an amazing difference .. she would only get to 14 psi prior to the vlaves going in. Im fine with that as its a long term vehicle for me and the missus

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Originally Posted by timbo2410

Haha i bet it did. One psi higher on mine was an amazing difference .. she would only get to 14 psi prior to the vlaves going in. Im fine with that as its a long term vehicle for me and the missus

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Don't be scared off about high boost pressure. The myths of high boost pressure and the ZD "grenading" is false. From my many years of selling the Dawes and needle valve kits, installing them etc and seeing a stock motor running a boost gauge alone. its the poor ECU control, low boost and super high EGTs combined together I truely believe is the main contributor to the premature death of this zippy little donk.

Most ZD's however will chuck a wobbly when they hit 16psi and throw you into limp mode. Theres a few ways around this now, one is to run a resistor in one of the wires to the air flow meter, not sure of which one but a google search will reveal what and how to do. Then there is a ECU remap. Expensive and irreversible. But proven. Then theres what I did. Buy a HPD billet air flow meter housing. Prior to this, I could not go past 16psi. After installation, I could get boost of the 30psi gauge and still not get limp mode.

Also make sure your intercooler is 100% sealed, and ditch the shitty OEM scoop and buy a taller scoop to trap more air. Also a bigger exhaust helps a heap too. 3inch is the sweet spot. 2.75" for the CRd ZDs is another myth, just a selling hype made up from whoever it was those years ago to get people to buy their pipes.

| also noted better fuel economy (i thought that around 10l per 100 was good), but now its around 8. Nothing else has been done (not even the service) between when the valves were installed and when I took note of economy. I kinda wish I had bought the auto .. it would be a lot easier crawling around the tracks and rocky sections .. it would also be easier in traffic. Had a 3.0 blow past me from a standing start .. it is what it is I suppose. I also dont like the clutch. Feels like a lot of backlash but the mechanics have said it's all good ..

Get some more boost into it and you won't have that 3.0 blow past you again.

I installed a Needle and Dawes valve on the ZD30 and adjusted boost to 18psi, all good. When I started adjusting the needle valve the boost dropped. Is this normal or have I installed something incorrectly? Also when adjusting the needle I am having trouble picking what is changing apart from the boost.

Your max boost won't change, well it shouldn't unless you have the needle valve open too far. The needle valves purpose is to control how fast the boost will rise, the Dawes is just a boost limiter. If you open the needle valve wide open and go for a drive, you will see the boost rise very slowly and the car will feel sluggish. As you shut the air supply off from the needle valve, the boost will start to rise quicker. Then its just a matter of finding that sweet spot. its a set and forget setup too. So theres no need to run the needle valve in the cab like many do.