Thread: Dawes Valve - Development (VNT) HELP

really, i ordered mine about a month ago, and nothing for a few weeks, then i emailed them to find out what was going on and the next day i got a consignment note saying it had been dispatched, arrived about a week later. much easier than making one

Originally Posted by 08Bender

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What is lacking from the original? How can we improve it? I really hope to come up with a better product with a higher level of control and user option for setup.
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Adjustability under part load is primarily what is lacking.

Link up a cable from your throttle pedal which then applies pressure to the spring in the valve to adjust maximum boost depending on throttle position - could be tricky to setup.

Have similar cable to a valve on boost line to your 'dawes' valve which releases signal pressure in relation to throttle position - can't see it being easy to make linear.

Food for thought quickly off the top of my head.

Thanks Sheldon,

Just the input I was hoping for! I'll get my valve to function tomorrow and go from there. I have seen a few rather elaborate setups on a few alternate fuel forums

Anyone else? Who is 100% happy with the original Dawes valve?

Tristan.

am interested to see what peoples have done here, only because my dawes valve is sitting next to my computer, its a long long way down the list of things to install on my rangie

The GT2256V turbo I had on a 300Tdi used a boost pressure actuator, so I never tried a dawes valve with it. I have used dawes valves with normal waste gate turbos, but those were the type with a bleed hole, unlike the the dawes for vnt turbos with a vacuum actuator.

Some people with vnt turbo and boost actuators, or with vacuum actuators and dawes valve have devised methods to improve operation at cruise speed. At cruise when boost isn't needed, moving the vanes to reduce drive pressure in the exhaust manifold gives improved economy.

Edit: this link will take you to a thread in a merc forum that uses valves similar to dawes.

Sorry can't find the thread in another forum that used a piggy back cable from stock accel cable to change vane position at low load.

Update...

So it's installed and working just as a Dawes Valve but I plumbed the throttling valve differently. I am going to make another valve tomorrow but will make the body a little bigger. I will include an electric solinoid to isolate vacuum for cruising, that will decrease back pressure when boost isn't required.

I'm also going to incorporate the throttling valve into the main body to still allow adjustment however I might plumb it as a bleed valve as per the standard setup.

I went for a drive in Insides Perentie to gauge the difference today, he has a Dawes Valve and VNT. Function was the same but his was set higher and pulled much better. I'm going to wind my fuel screw out a turn and turn my pressure up tomorrow, maybe Monday.

Overall though, looks like it might be enough. It seems to have good control from idle through to max boost. It does sound like it has a busted muffler with the vanes closed though

I had a picture but photobucket isn't playing the game today, sorry!

Tristan

Originally Posted by Bush65

Sorry can't find the thread in another forum that used a piggy back cable from stock accel cable to change vane position at low load.

If my memory is still working, I once read a 1.6td VW article where the owner was running three mechanical inputs. Throttle, boost feedback and can't recall the third.

Hi,

OK, so my Dawes valve has been 5 doors up at the wrong address for nearly a week. Glad he decided to drop it over though and not mail it back to the States! I swapped it over for mine, does control boost a-lot better. The spring is in the Dawes valve is much lighter than mine, makes good sense now

I will still continue with the little project though. It works very well as it is but I think I can have it open the vanes automatically when I'm not on the throttle pedal. I just need to find a rotary throttling valve to control vacuum. Ordered lots of fittings and valves from eBay (China) last night.

Valve V1.0 below

Cheers, Tristan