Dawes valve set up

[Rock Trol]

Hi everyone. I have just installed a HPD Dawes valve to my CRD Patrol to stop the over boosting caused by the new 3 inch exhaust. Two separate suppliers advised that I just isolate the solenoid and hook up the Dawes valve directly to the vacuum pump and then to the turbo. I do not have a needle valve installed.

This seems to be working fine on the patrol. I drove it around town as well on the open road (110 km) and boost was linear. It would spike up to 16-17psi and then settle down to 14psi on the highway. Around town its 10-12psi or lower when not under load. The question I have is that most of the diagrams I see still keep the factory vacuum solenoid or use a needle valve so are these rally needed? On my car its just the Dawes valve connected between the vacuum pump and turbo.

Here is a link to an earlier version of the HPD Boost controller. Would this be any different to the older style Dawes valve as the instructions say to just bypass the solenoid.
http://gcg.com.au/category/performance-parts/boost-controllers/hpd-vnt-controller/vnt-manual-boost-controller-detail

Also, where should the dampener be placed? Between the turbo and valve (currently set this way) or the valve and vacuum pump? Or does it not matter?
Originally it was between the control solenoid and turbo.

[Rock Trol]

OK, I've found an answer (by Chaz Y.) to the question regarding the original solenoid on another forum. It's OK to bypass the solenoid if egr is blanked.

Now, does the position of the dampener matter?

[threedogs]

As long as its between the vacuum pump and dawes you will be fine,
what are your EGTs on the HWY?

[Rock Trol]

Hi threedogs. I don't have an egt gauge on the patrol. I use the water temp feature on the scangauge to monitor the motor. Yesterday was overcast and muggy, I had the aircon on and the highest the temp would go was 88 degrees celcius on the highway. Mainly stayed on 87 degrees. Before the exhaust and retune I would have been on 89-90 degrees so I think it is running a little cooler.

Have not had a chance to tow up a big hill at speed (Sturt Hwy going to Melb) yet as I have family from interstate visiting. Planning to tow to Morgan next weekend so will know more.
Sounds like I should swap the dampener to the other side of the Dawes valve.

[kevin07]

I would suggest a egt gauge be your next priority as your engine temp has absolutely nothing to do with egts

[threedogs]

Boost sounds about right if not a tad high, but all motors are different.
I'd take on board what Kevin has suggested and start fitting a boost and EGT gauge
to monitor whats happening under the bonnet, then you can "drive" by your gauges

[mudski]

The vacuum solenoid on the patrols is a two stage set up, three ports. It controls boost and spool up rate, one port for vacuum supply, the other two for max boost and spool up rate, if you want to call it that. Just about every other car I have seen, Triton, Ranger and Navara, with the VNT turbo it only has a single stage solenoid, two ports, supply and delivery to the turbo. One line in from the pump and one line out to the turbo. In this case you do completely by pass the solenoid.
In your case you cant. The solenoid still relies on the "bleed port", the third port on the solenoid which goes to the air resonator box, to let some of the vacuum pressure in and out to control the spool up rate. Using a needle valve in replace of the third port to control the "vacuum bleed" takes away the final control of the vacuum solenoid.
You still can do what you have done, but obviously the ECU is designed differently to the other vehicles and is designed for the three ports. So the way you have done it you have no control on spool up rate and you wont be getting the right performance out of your ride.
If you want to continue to not use a needle valve I would be putting the vacuum supply back onto the end port of the solenoid, the middle port to the Dawes and the inner port to the air resonator box. That is how it is done when NOT using a needle valve.

Edit : I just looked at the link the OP supplied. Going by their description it would be for the single stage solenoid setup, like a Triton. Love their price too. lol.
Edit 2 : Just my personal opinion here and only going by my own experience from fitting these to numerous CRD's now. Not fitting the needle valve is only doing half the job. Mechanics say you don't "need" a needle valve. Well, you don't need the dawes either. You are only modifying your car to make it run better and smoother. It is proven that the needle valve, when used with a Dawes, makes the setup a crap load better, same as adjusting the VNT screw. People go to amazing lengths and install big exhausts, chips, bigger and better air intakes etc etc. It takes a whole 10 minutes to instal. So why wouldn't you put one in?

[Rock Trol]

Thanks Mudski. While I am not getting any problems with the spool at the moment, having more control is probably beneficial. Looking at your needle valve at the moment on ebay. Looks good.

[Rock Trol]

I fitted the needle valve from Northern 4x4 yesterday afternoon. After some testing and tuning I have the engine running very nicely indeed. At around 100kph the boost sits between 11-12 psi and under gentle load its about 14.5psi. If I floor it the boost gets up to the 15.5-15.9psi so I am very happy with that.

This is the nicest that the Patrol has ever run. Plenty of power yet very smooth as the boost is linear and matches the amount of fuel being added to the engine. While my egr block has been in for 18 months and I did not have any major issues with boost (until 3 inch zhaust), I regret not doing the dawes/needle valve earlier as the engine is so predictable now. :smiley_thumbs_up: