Thank you Grim for the thorough explanation. Now I understand. One thing I'm curious about, the WMW and JCW DV's basically have a stronger spring. What is the benefit of that, relative to how the car performs?
Using a stiffer spring helps with boost recovery. The valve is a solenoid so it's opened with a magnet and closed with the spring. The stiffer the spring the faster it shuts. The faster the valve is closed the quicker the boost is diverted back to the engine. It won't add power but it helps maintain it.
The VAG components employ a stiffer spring also. The hot air is on the turbine side. Heated air on the compressor side is a relative function of boost pressure, which is the same no matter the type of diverter valve is in use. The energy required to spin the turbine is a percentage of exhaust flow, there is no power robbing waste here. The singular focused view, which I think is a perceptual fallacy, is considering the stock diverter valve as the gold standard. It's analogous to some camshafts and/or tunes, where abrupt transitions are considered proof of performance whether or not an alternative would produce equal performance before the spike. The VAG modification is not a performance bolt-on, nor is it the power robbing let down some would try to rationalize. Its strength is component durability. Since 100% of stock DV diaphragms I've removed had at least a "pin hole", I suspect the majority of stock DVs in use are compromised. Grim, your subjective impression is no less valid than other positive experiences, so your report is not in question. I do challenge you to dig deeper and locate a "pin hole" effect measurement in regards to the R56 VAG modification.
So the JCW/WMW DV is it strictly a beefier spring or is the diaphram a bit thicker too to prevent pinholes or tearing?
To help make my point more clear it would be best to start by showing why the stock DV is being replaced. Under normal working conditions the DV should close and seal keeping compressed air in the charged air portion of the intake system. When the diaphragm is compromised ( torn, ripped, punctured ) compressed air will leak into the intake system causing boost loss and the inevitable limp mode. Now the VAG unit does away with the diaphragm so in theory the issue is solved. This might be true if the MINI's turbo housing had the proper depth to alow the VAG unit to be installed correctly. The way the VAG seals is with a semi soft ring around a tapered piston with in the large outer plastic ring. When fully shut the ring seals on its inner edge against the piston. The outer edges of the ring seal against the large plastic ring surrounding it. Again this is nice since it can't tear or what have you. The problem is the VAG unit is too long for the depth of the hole th DV bolts into. MINI DV is on the left the VAG DV is on the right. Note the differnce in height. What happens is when the VAG DV is installed into the MINI turbo it pushes the piston in mimicking it's opened state in a sense. Although the piston is snug against the housing the ring is no longer seated against the tapered edges of the piston or the outer ring and causes the same leak that a damaged stock DV has.
Replying in 2 different post as the first one I wanted to address the problem the VAG DV has and not have the rest of my response mixed up in it. Your correct on how heat and pressure are generated with a turbo. However with a damaged or leaking DV the way and amount both are generated changes on the R56 because both the DV and waste gate are computer controlled. The ECU can force the waste gate in any position with in it's free travel. What happens with the leaking DV is boost is being bled off. So the ECU forces the waste gate closed to allow the turbo to spin faster and generate the boost its looking for. What happens now is the turbo is spinning at a rate that normally yields say 20 psi but is only producing 15 psi. This adds more heated air to the intake charge, introduces turbo lag and, something i forgot to mention, over spins the turbo thus shortening it's life span. The stock DV is in no way a perfect part and isn't the gold standard to me at least either. I look at it more as the lesser of 2 evils as it does work when it's not damaged. The VAG DV is not working correctly right from the start so i see it as an inferior replacement over the functional OE units or the Forge DV. In terms of reliability there is already a strike against it as it basically has the torn diaphragm effect. Second the parts are still plastic and are subject to melting under heavy loads just like the stock DV is. So there really is no major durability gain from installing this either.
It might be beefier, not really sure TBH. I haven't taken the time to really look at the 2010 + DV's and compare it to the older ones. FWIW I can say I've seen more problems with pre 2010 DV's as apposed to the newer ones on both street and track cars, so maybe. Could just be an age factor too though.
The spring was once the only difference, all MINI DV models are currently the same, regular S and JCW. The VAG modification does not cause the same leak as a damaged diaphragm. If there was an abnormality, fail safe mechanisms would let you know. The VAG piston seals within its housing, not its outer ring, the housing butts against the same spot the stock unit does. Spring tension will elevate the MINI DV to the same height as the VAG's outer ring. The measurement you will be challenged to find would be datalogue related. Bench testing is fine and dandy, but it's how the modification behaves in operation that would illustrate whether the difference is significant; I know it is insignificant. You're stretching the fear and doubt propaganda too far Grim. Care to prove the gross exageration about the turbo spin rate to produce 15psi with the VAG modification? Can you show us any data of pressure loss via the VAG modification? How about showing us a melted VAG housing? You should be able to locate an example since they've been in operation for 3 years. How about showing us a melted stock DV since you say they can melt also? Have you ever installed the Forge unit you're promoting? I know you have not or you wouldn't be calling it superior.
Dataloging is fine and the raw data would definitely help my point. However I did not bother with it when I had it on my car or any customer cars as there was a noticeable negative change in the cars, especially those that had raised boost. I may have gone though the trouble to see the exact amount of loss, but it's a $60 part that takes 15 min to install. I'm not gonna waste that much shop time to prove to my self something i can already tell is not working right. I did reinspect the unit and found it's fault. between that and the way the cars feel I really did not need any more info. There is six holes in the face of the piston. Installed on the correct application these holes serve to alow air flow through the piston so the solenoid is not trying to compress air behind it and so a vacuum is not formed preventing it from closing. Now if that area behind the piston is not sealed like it's supposed to be then pressurized air will pass through the piston, though the areas that should be sealed and into the intake side of the turbo. The ring the piston slides in is a seal and needs to be able seal to work correctly. If air passes around it then it is causing a leak in the same manor a torn diaphragm does, but like i said not to the same extent as the area is not that large to create leaks like some of the badly damaged stock units. None the less it is a leak. The "gross exaggeration" as you put it was an example using arbitrary numbers to demonstrate the differences in turbine speeds. It was in no way a statement saying the VAG DV will add any boost or the boost levels it operates with. Further more general knowledge and experience of what happens with leaking DV's or BOV's will let me know what to expect from a turbo with out measuring turbine speeds for a specific application. I may not be able to provide exact numbers, but I can tell you it will be spinning faster then intended. This also explains why many report that they gain 1-2 peak PSI after the install. It may seem cool, but the turbo is being over worked as a result. The effective efficacy and turbo life span are hurt as a result. It may seem insignificant to you, but I would much rather take the chance on needing to replace a $60 part for the time being, then risk damaging a $1500 one. I admitting don't have a pic of a melted VAG DV nor have i seen it yet, but this is why i said it's subject to melting and not that it will. I have personally seen numerous MINI DV's melt, crack and deform in track conditions though. I have a pic some where I just have to find it. I am aware the Forge DV is subject to it's own issues and I am not promoting it any more then the other DV's I mentioned. I only brought it up as one of the few other options available. So far I have yet to see any real good solutions to prevent DV failures applied to the R56.
I interpret that retraction as you don't think the VAG mod affects boost, but you also site claims it causes more boost; another contradiction hard to come to terms with. S & JCW turbos can exceed their psi limits with the MINI DV on a stock tune; that's not much of a definitive correlation one way or the other either. I can understand the rational as I think you're stating it, but there's disconnect between your theory and my application. No boost discrepancy codes or limp mode, so the ECU doesn't support the theory of significant boost degradation either.
With in the context of the first statement you refer to I did not state it added boost. And I'll say it again the DV does not add boost, it can't add boost and never will add boost. The best any DV mod can do is maintain boost. The increase in boost is a result of the ECU correcting for a minor boost leak that is not big enough to throw a code, but large enough for an adaptation to be made. This correction is to close the waste gate allowing the turbine to spin faster and create the boost level it's targeting. Like I said because the turbine is now spinning faster it will over shoot it's target at peak and create a higher boost level. You mentioned before you see many stock units with pin holes and speculate many others are damaged in the same way unbeknown to the owner of the car. These units are leaking too, but the car has not thrown a code or as you said again there would be a very noticeable fail safe activated. The ECU works off parameters. It will only make changes based on what it's programed to do. With any DV f the leak is not large enough to trigger the fail safe it does not mean it is not large enough for it to see an issue and correct for it. It just so happens the correction is not always good for performance nor the life of the turbo, but why should it be, its correcting for a part that is not working right. The big issue is that by installing the VAG DV your guaranteeing the leak will be present. Now the effects may be favorable for some and the car seems to work fine in their own mind, but it does not change the fact of whats actually happening.
I'm with Grim on this, I had to buy this DV and swap inerds to try. I understand what he means and the others, and I also understand the other side. I feel the pros and the cons of the Audi valve. For a driver like me it's a huge con. The boost feels inconsistent when shifting doing WOT runs. The engine response feels like a heatsoaked FMIC when pushing your car flat out, this is in 70* weather at 830pm. I don't know wtf is happening but once I get my AP on Friday I hope to see some logs and see what the psi is running at WOT and all RPM. Btw the car hiccup'd 2 times and fell flat on it's face when WOT (like drag racing). When you are WOT and reaching 80mph in 3 or even 4th gear the turbo feels overworked and like it's blowing hot air and the car doesn't accelerate as fast like it did with stock DV. During normal driving the car does in fact feel responsive like an N/A car; silent blow off, lag free, low rpm tq unlike stock DV BUT I know the car is down on power in the mid to high rpm range. I'd say if your stock DV is ripped then this will obviously feel better. If you drive normal and a lot of city driving then this feels better. If the majority of your driving is not WOT, then this valve will feel perfect. If you are racing or autocrossing with Audi DV this not what you want, feels like a bottleneck. I'm a very "intuned" driver. I have a very good seat of pants meter. I know before I see logs and run further testing that valve is not good. My advice: Either get the ALTA spring or upgrade to Forge. I ordered the ALTA spring and when that arrives my stock DV is going back in. FWIW this was on my 2007 MCSm with JCW Stage 1 and ALTA JCW drop in foam filter.
This sounds like your going into a soft limp mode. Basically your engine over shoots the load target set by the ECU, causes a boost spike and triggers a soft limp. This cuts boost to about 5-6 psi It should reset when you lift off the gas. This is common for aggressively tunes R56's but I have seen it happen to stock cars on occasion. I had a driver that used to trigger it all the time on the track from left foot braking.
k-heuvo, it started after I installed the DV, all is connected, I check for leaks.. none. My car was just fine before this part, I got it out of curiosity, not to replace anything that broke. Grim, that's what I think it is. 15+ psi to 5psi is like falling flat on it's face, and if it overboosted then that would cause the heatsoak. The DV is causing this to happen it's the only variable recently changed. BTW Besides the JCW S1 that's been on the car for over 3 years, and a ALTA Foam filter that's really all the mods I have until Friday.
Update: I think the ecu is adjusting to the valve, whether it's adjusting to cope with it like pulling timing is the question. Again I don't have logs or gauges showing me what my temps and psi are. I have got on it a couple of times(highway pulls) but it didn't go into a limp mode feeling but it still feels like it's bleeding or bottle-necking at high rpm still in 3rd gear. Before I could run out to 6krpm easily but when it hits around 4500+rpm in 3rd it feels really down on power up to 6k unlike before, pulled timing? Question: -What is the outer ring used for?? MINI OEM DV doesn't have it, the previous Audi DV didn't have it. -How about trimming/removing the outer ring? -Is the AUDI "D" "valve" sitting on top of the compressor hole or is it snugged in the hole, unlike previous AudiDV and MiniDV that sit on top with a rubber gasket on "valve" face. I see 2 things that are debatable. 1. No rubber on head of valve giving it a nice seal. Metal to metal? 2. Outer ring causing a blow off restriction or slowing of air to escape. Let me know what you guys think.
With out logs and seeing the car in person its hard to tell what the exact problem is. Although I'm not a fan of the VAG DV on th MINI I'm not so certain that your issue is related. I've seen the VAG DV exasperate issues like this but have yet to see or hear of it being the direct cause. It could be, but it's hard to tell from behind the keyboard. The outer ring holds the assembly together and is needed for proper function. The previous DV's had it as well, they are just different in design. Judging by it's larger size and the holes, I would speculate it's purpose is to also help lower the sound levels produced when venting pressure. It may hold air in to some degree, but it shouldn't be restrictive to the point of causing an issue. If anything when all things are working correctly it could help boost recovery in some slight amount. The piston rest against the turbo housing the same way the previous DV pistons did, but as you noticed there is no rubber seal there any more. It's arguable if the piston design is flawed in this regard. Most reviews of the VAG DV are positive in regards to their intended applications, but there are negative reviews as well. Over all I like the VAG DV design. It still has potential flaws, but it's a nice improvement over the previous Audi/VW units. If it fit properly on the MINI turbo I would probably still use it and endorse it.
Well I took a horrible vid but you can see from the rev halt and the long moment between 55-73mph it falls flat on it's face since the AudiDV swap. I stopped because the car was going nowhere at that point. Forgive the harsh commentary, long day. 1st, 2nd, 3rd and 4th WOT, fast shifting, with SPORT ON and DSC OFF. [ame="http://s35.photobucket.com/albums/d164/PaImportTuner/?action=view¤t=video-2011-08-25-19-21-09.mp4"]video-2011-08-25-19-21-09.mp4 video by PaImportTuner - Photobucket[/ame]
At any rate tomorrow I'm going back to stock DV with Alta spring tomorrow, if I'm not happy with that Forge here I come. I'll take a vid too.