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geeyoutoo

Dawes Setup Dual or Single

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For anyone wishing to fit and tune a Dawes valve system. The following shows an in cab needle setup and single or dual Dawes valves.

Single Dawes setup with early model vacuum surge canister, the tank is not really needed and often one of the barbs will break off so bypassing is OK, if you don't have one (around 2002/2003 it was deleted anyway) just go straight to the vacuum take off point under the IC

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This is the dual dawes setup, the same info as above applies to the surge canister, the solenoid that controls which dawes is selected is setup to default to the high boost side if the solenoid fails, this could be handy when doing a lot of towing

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This is the standard setup for ecu control of vacuum to the VNT through the ECU

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This is the bypassed vacuum switch giving more linear control of the VNT vac hence better boost control

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My personally prefered position for the boost take off point, easy access and easily protected

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Internal view of the fitting in the IC inlet pipe showing a smooth transfer

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External finished view of boost take off point

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Boost line from take off point is 4mm ID, the gauge usually has 3mm OD (1mm ID) tube, so a 3mm quick fit coupling was adapted to a 1/8th BSP barb fitting to make the transfer of size before the 3mm tube went through the firewall, The 3mm tube was pushed inside 6mm airline which made a protective shield before passing into the firewall

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Vacuum damper relocated as schematic

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Dual or single Dawes secured inside a rubber shield and cabled to the loom on the passenger side

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Location of needle valve in the cab, this hole exists and only needs opening a little, the needle valve has been fitted with 90 degree 1/8th BSP fittings for ease of tube attachment

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Fabricated a steel bracket to hold the dual Dawes solenoid to an existing threaded hole in the firewall

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Location of dual Dawes solenoid control switch beside driving light switch, picked up power from the cigarette lighter

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Dual Dawes solenoid and Dawes overview

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Dual Dawes Solenoid and Tube overview

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Could you please indicates suitable values for the two boost pressures settings on the individual Dawes valves?

My 2002 GU Y61 has already “hand grenaded” and been rebuilt with EGR blanked off, catch can fitted, needle valve and single Dawes (giving 14 psi boost) in place, and an electric Boost Controller Switch and second Dawes valve supplied.  The mod.s are working well and I would now like to fit and use the second Dawes valve, hence the question regarding recommended pressure settings.

The vehicle is running 33” x 16” tyres, a 50mm suspension raise and spring/shock absorber upgrade with a 3” exhaust and front winch/bar replacement.  It is used mostly for off-roads and also a bit of camper trailer towing (about 1500 kg).

I have read quite a bit of yours and others output about this “interesting” engine with great attention, but have not come across much in the way of definitive guide lines on these pressure values involved.

Many thanks for your continuing interest and output and I look forward to your reply.  

Cheers,

Rico.

,

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G'day,

The above is now pretty much just as historical info. Most of us have moved on onto next level which is basically re-mapped engine ECU making Dawes valve and similar as such redundant. The reason for Dawes valve or Timid valve are still valid though in case the factory ECU map is used.

I run combo Dawes with Tilix  valve because I have retained the dual boost control setup I had before going full re-map. GU2 has reinstalled factory boost control since the re-map fixes the short comings of the factory setup (limp mode due to overboost etc.)

I have retained manual overide so I can force low boost ( set to 14 psi)on  Dawes valve for economy or high boost setting ( 24 psi) on Tilix valve for mx power output and auto switching based on TPS percentage via voltage switch.  Before re-map high boost was set to 18 psi due to factory induced limits.

Regards

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