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Engine Specific Info and Questions => TDI Engine -General Info => Topic started by: 55eta on July 13, 2010, 02:45:33 pm
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Just wondering if anyone have used the dawes valve vnt controller sold by 3barr racing as it looks like a very simple set up and cheap product
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Retail on the valve is $14 at Mc Master Carr or Grainger.
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Thanks,but was looking for some feed back on the performance of them as i have seen a few posts on other forums that are a bit conflicting ,some have done away with the ecu control in favor of the dawes valve and claim a much flatter boost curve than the ecu control but others agree with the smother boost curve but reckon they produce a higher boost at cruising speed ,which in my eyes cannot be good for the longevity of the turbo.but the simplicity and adjustability of them when used with a needle valve is what interests me but i am still sceptical ,can something that simple produce such good control/performance?
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link http://www.chaz.yellowfoot.org/Manual Boost Controller.htm (http://www.chaz.yellowfoot.org/Manual Boost Controller.htm)
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That Dawes-controlled boost map looks like you're waiting for a long time for boost to build up...gutless bottom end. I thought one of the attractions of the VNT was the ability to build high boost levels early in the RPM range?
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Yes looks a bit that way i think that's where the criticism on other post i read came from{but sounded like a boy racer posted it} ,if you want high boost at low rpm you can achieve it but the trade of is high psi at cruising speeds that's why i am looking to see if anyone has used them just to get a clearer view of there performance ,the one in the link is on a big 4+4 and a flat boost curve would be a good thing off roading boost spikes=wheel spin .so still waiting to hear from someone who have used them in a daily drive as i have a vnt but don't want to go to the trouble off fitting it{the vnt} only to find out they are $hit {the valve}
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Yeah, I'll be watching as well. I have experience with manual boost controllers on my Subaru, (non-vnt) I'm curious about the Dawes setup, never heard of it before.
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A single valve alone will not work for a VNT. You need multiple stages to limit boost by engine load.
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A single valve alone will not work for a VNT. You need multiple stages to limit boost by engine load.
If you look at the system in the link in the 4th post, there are two valves one to control vacuum{needle valve} which operates the vnt control cylinder and the Dawes valve, which is boost controlled which controls the vacuum supply to the control cylinder to me it seems like it has a infinite amount of stages?but like i have said in earlier posts im looking for some feed back from some one who have used one on a daily driver
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No, it doesn't quite work that way. The needle valve will flood the vacuum system with air and make the other vacuum consumers inoperable.
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No, it doesn't quite work that way. The needle valve will flood the vacuum system with air and make the other vacuum consumers inoperable.
I can see where you are coming from but don't think that to be the case as i have read a couple of post which have give conflicting view's of the valve but none to suggest that ,also the link says you can use the ecu control combined with it which would include the N75 valve which is a electronically controlled vacuum valve.by the the way the the link is not from the manufactures of the valve but a australian off road er just using the product ,so there is no vested interest trying to sell something .The way I'm thinking at the moment is there has to be something in it for him to make a perfectly good ecu controled unit redundant in favor of it
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The dawes device when used with the standard ECM is not for primary control of boost, its to prevent boost spikes caused by the computer's natural time lag.
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The dawes device when used with the standard ECM is not for primary control of boost, its to prevent boost spikes caused by the computer's natural time lag.
So what its purpose when no ecu is used? is it there just to make all the other vacuum consumers inoperable as a single valve cannot control a vnt?
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Its not used without the ECU.
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Correct, it should be noted that the dawes device is not a VNT controller.
Brendan
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Correct, it should be noted that the dawes device is not a VNT controller.
Brendan
I think you need to look more closely at the link in the 4th post on this thread ???
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Its not used without the ECU.
Look at the drawing on the link the one in with the pictures of the engine bay pluming ,can you se a n75 type valve there ? i think not
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Look at the drawing on the link the one in with the pictures of the engine bay pluming ,can you se a n75 type valve there ? i think not
Look at the drawing on the link the one in with the pictures of the engine bay pluming ,can you see where it says "Dawes Valve Fitted With Factory ECU Controlled Vacuum Solenoid".
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Look at the drawing on the link the one in with the pictures of the engine bay pluming ,can you se a n75 type valve there ? i think not
Look at the drawing on the link the one in with the pictures of the engine bay pluming ,can you see where it says "Dawes Valve Fitted With Factory ECU Controlled Vacuum Solenoid".
you are looking at the wrong drawing look up the page ther is another click on it to expand it an then read the rest of the page after
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Not sure about the dawes valve but I asked a local turbo specialist that builds hybid turbo's , and was told about the product below would this work for the vnt you have ?
http://www.performance-wise.com/page42.htm (http://www.performance-wise.com/page42.htm)
HDI BOOST CONTROL KIT & EVOLUTION BOOST GAUGE
I asked if this needs a signal for the engines rpm's he said not ,
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you are looking at the wrong drawing[/quote]
That is the only valid drawing.
Using a single dawes valve alone would be no different than replacing the vacuum actuator with a normal wastegate actuator. You'll get very high exhaust pressure at cruising speeds and there is no way to limit boost to the engine load. It's all or nothing, always trying to get the boost to maximum under any conditions. In a correct system the ECU is only what controls pressure, the dawes valve prevents boost spikes due to the computer and solenoid lag time.
If you want a dawes valve system alone with no computer you must have a way to limit boost in low load conditions. I do this by using 3 dawes valves and two throttle position valves, others use a cable system to move the vanes with an actuator just to limit boost.
Controllers for watstegated turbos do not work the same with a VNT. A wastegate only limits boost pressure, a VNT actuator controls boost pressure.
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you are looking at the wrong drawing
That is the only valid drawing.
Using a single dawes valve alone would be no different than replacing the vacuum actuator with a normal waste gate actuator. You'll get very high exhaust pressure at cruising speeds and there is no way to limit boost to the engine load. It's all or nothing, always trying to get the boost to maximum under any conditions. In a correct system the ECU is only what controls pressure, the dawes valve prevents boost spikes due to the computer and solenoid lag time.
If you want a dawes valve system alone with no computer you must have a way to limit boost in low load conditions. I do this by using 3 dawes valves and two throttle position valves, others use a cable system to move the vanes with an actuator just to limit boost.
Controllers for watstegated turbos do not work the same with a VNT. A wastegate only limits boost pressure, a VNT actuator controls boost pressure.
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Top off the page there are 7 pictures [of the engine bay] and one drawing ,this is the drawing you need to look at and then note the third line of text that explains the use of said vale without ecu control solenoid
I have now fitted the valve and vnt , it now dose what it said on the box [with regards to the valve] all though the boost is a little high [8-10psi ] when cruising with light throttle there is verey little if nothing in the way off boost spikes /surge and this is installed on a aaz ,well impressed for a simple valve and a needle valve ,it is never going to be as good as ecu control but for the money it is not expected to be but it`s a big improvement on the waste gate turbo i had and it fulfilled my main goal which was to reduce egt which it did by about15-20% using the same fueling and boost as i had with the w/g turbo and it did not flood the vacuum system with air as some said it would
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That's great to hear; I've been looking at that Aussie plumbing design for some time & have been getting closer & closer to going for it.
http://www.chaz.yellowfoot.org/Schematic.htm (http://www.chaz.yellowfoot.org/Schematic.htm)
One thought I had was to use a ball valve attached to the throttle arm in series with the needle valve to get some throttle position input for more boost at full throttle using the vnt arm set screw to limit boost ability at too low of rpm. Full throttle would then close off the needle valve line putting full vacuum to the vnt actuator. At least I think that would work...