Ok guys, as per tittle this is a thread about the recirculation valve commonly referred to as the DV (dump valve) or BOV (blow off valve).

Now I might be about to upset a few of you and I'm certainly going to show you why the internals of the VAG (06H 145 710D) recirculation valve is a NOT a worthwhile modification!

So lets first look at the design of the nose of both valves.



On this photo below just take not of the vent holes in this VAG valve!



Now besides the obvious, pay attention to the VAG valve on the RIGHT of the picture, and the inner ring, when this inner ring is seated against the flat machined surface of the turbo compressor housing, how does it seal itself against the building boost pressure ?

So now i've got you thinking lets look at that surface in the compressor housing.



Ok lets simulate the VAG valve as if it was in situ, now for this simulation I have used a flat washer.



As you can now clearly see that when in situ, it will leak building boost pressure all the time, as there is no way for it to seal against the machined surface, and this will slow the spooling time of the turbo!

Ok I hear you all shouting at me, but I've not lost any boost pressure after I fitted the VAG valve, the actual boost pressure drop is very little (yes I have measured it) and nothing to worry about, however with this VAG valve fitted you are loosing (slowing) spool up time and will never ever get the benefits of the stock recirculation valve fitted with a different rated spring.

 

Hmmm, a good point actually. I don't know enough about it to refute your claims. i was going to install the valve this weekend.

Reports after the upgrade have been really good though.

You should post this here as well: https://www.northamericanmotoring.co...heck-this.html

You'd get some feedback faster in that thread.

 

mmm, mine doesnt seem to leak boost and I have had it on for a few years? However mine is not the designe that you are showing, thats the newer designed VAG one.

 

thanks, czar, thats pretty helpful i installed the audi 710D this week and didn't really notice much improvement; if anything i may have been about one psi less in boost according to the gauges.

just for grins- can you post a similar pic but showing the washer sitting on the oem dv? (i assume the diameter of the washer's inner opening is identical/similar to the turbo compressor's opening?).
charlie

 

When you install the VAG valve aren't you only supposed to switch the internals? Is the part you're showing with all the holes leaking boost part of the "internals" as mentioned in the other thread here about the Audi valve?

 

yes, that part is part of the "internals"

 

While I completely believe you and really do trust your judgement and knowledge about ANYTHING R56 related....why does the 710D seemingly create such an improvement? And why are people seeing it hold boost better than the stock valve? Just wondering...

Surely its not just placebo effect, because the difference on my car was absolutely night and day.

 

I'm curious about this too. Maybe the picture of the valve with the washer is what the valve would look like in the open position?

Correct me if I'm wrong, but doesn't the spring press down on the valve from behind that would surely result in some kind of closing/sealing effect against the valve top?

Looking at your third photo the opening appears to be smaller than that of the washer. Maybe in the closed position with the spring depressing on the diaphragm it makes a complete seal?

If it's a placebo effect it sure seems to be a good one because most of the reports after the upgrade have been great and, as Thumper said, boost pressures have been verified to be higher.

 

And also like I said, I'm not very sensitive to these "cheap, easy, amazing difference" mods usually. Most of the time I think they are placebo. So when I was throwing the 710D on I wasn't expecting that much, but it was huge....

And I'm not doubting czar at all...he probably knows more about this car than anyone on here. I just want to know why everyone is seeing such great results, if its apparently leaking boost....

 

I agree with ThumperMCS. I installed the 710D today, and I thought the difference was like he said "night and day"
While Mrs "don't you think you're going a little too fast" or "my neck hurts when you shift like that" was along for the ride, the shifting was smoother, and I thought the all around response was better. Psi might have dropped a little watching the guage, but then again, motoring conditions weren't ideal with 'you know who' along. On the whole, so far I like it. Will try and get a better feel for it when I can be alone .

 

You must be with my better half's sister! Mine could also be called Mrs "racing widow since you pay more attention to that car than to me"

 

I spent some time looking at this part my self when I first bought it. The holes seemed odd, but when installed they vent to a sealed cavity behind the valve.

I figured for the valve to be able to move it would need to pass air though it self. With out that ability the valve would have to compress the spring and the air trapped behind it.

I've been getting the same results as other people and have not felt a kind of power loss like you would from a leaking DV

 

Lets go back to the first photo, on the VAG valve the inner ring is the face which contacts the machined surface in the compressor housing, now if you look at the VAG valve, you will not see any rubber seal on the face of the inner ring!



And as there is no rubber seal on the inner ring face, you will never get a seal between the 2 mating contact surfaces, and even if there was a rubber seal on the VAG valve inner ring face, just pay attention to the amount and size of bypass vent holes, when compared to the stock valve!

Now the reason your all getting what seems like positive results from using this VAG valve is, the stock diaphragm valve suffers from heat degradation of the rubber diaphragm, the resistance of the rubber diaphragm (when new) aids the spring pressure, and so with the degradation of the rubber diaphragm, the resistance to hold the building boost pressure becomes weak, and therefore when you replace your stock unit with the VAG or another stock valve, then your simply feeling the effects of a new diaphragm/spring resistance when compared to your old unit.

Now look at the stock valve face, and it has a rubber seal to mate with the flat machined surface in the compressor housing, this creates a tight seal between the 2 mating surfaces.

yes the VAG unit does hold boost slightly longer, due to the length of the plunger which in turn compresses the same rate spring, which now is applying a greater spring coil resistance, hence holding back the building boost pressure for a slightly longer period of time, but at the expense of slower spool time, due to the mating surface of the compressor housing having a flat machined face, and the shape of the VAG inner ring sealing seat is conical, and as the 2 will never seal together, you are loosing (slowing) the building boost pressure, until such a point is reached that the incoming air pressure is greater than the escaping boost pressure through the vent holes!

 

I don't really understand what you are explaining,So what should we do? Leave the Valve,but change to the spring alta is selling?

What can we do about the rubber diaphragm?

 

If you don't want to loose spool up time, now don't get me wrong the difference in real time is only slight, however it is there nonetheless, and this spool up time will become more apparent with stock boost of 0.9bar than a modified boost pressure of 1.3 and above.

If you keep the stock recirculation valve, simply fit the Alta spring, and you will notice slightly quicker spool up and holding boost for longer, I have been testing the Alta spring for them here in the UK, and will post my findings in another thread.

As for heat degradation of the rubber diaphragm there is nothing you can do.

 

In the picture below you can see the old VW 06F 145 710 G DV on the Left and the new VW 06H 145 710 D DV on the Right.



The old one looks very similar to the stock MINI DV and would seem to pose the same problems for the VW's and Audi's if what you say is correct.

Since I didn't notice a power loss or change in acceleration the lack of the rubber seal didn't bother me much after I drove the car. However I do wonder how long the outer ring will last since it is so close to the housing. The stock ones already had issues with it melting or getting brittle and cracking. This ring posses a greater issue of breaking into smaller pieces with it's design. I plan on checking on it after a few 1000 more miles if it doesn't fail by then first.

 

Disclaimer, my knowledge of turbos, and the operation of the DV's hardly better than nil, however I have questions.
First, when the car was new, it never ran this smooth between shifts, or responded the way it does now.
I am thinking turbos are generally engineered in that they operate basically the same - no difference between Audi or MINI seeing the guts are interchangeable. Would an Audi turbo have a rubber sealing surface on the inside of the housing?
I see the small vents on the stock DV vent to the solenoid side of the housing, can't check the VAG cause it's in the car, but I would guess it's the same?
What is the "normal" position of the DV under cruising, accelerating conditions, spring pressure against the machined surface, valve closed, open during shifting to relieve pressure?
I may have more ? later. Thanks Czar, your knowledge is most respected.

 

Hi,

Dumb question, but surely if this valve leaks and delays spooling up, surely the same would apply for the VAG VW/Audi/Skoda engines into which it is installed as an oem unit?? Is there a wider flange to which this is applied in those engines?

Robbo

 

I believe you have to look at the valve mechanisme as a whole and not just the top part that contacts the turbo. If you can get the CAD drawings for each version of the valve I am sure you will find that they both work the way they should. I do not agree that VAG would create a valve that leaks by design.

Now mini might do that (ouch) JK.

 

i was wondering my self, i know the inner plug holes will just pressurize the actual unit, the seal around the opening is the real question.


What about the lip in the seating secion of the comp housing? It looks like there is a lip there, could the seat be against that lip instead on a fluch fit around the outer surface area?

 

Took the MINI out for a little ride without 'you know who' and after things warmed up, well, shifts were nice and crisp, had no trouble hitting 20 psi, spoolup was good as far as I'm concerned. Overall I don't think there is a problem with the design at all. I LIKE IT! The only thing that comes to mind is, being a member of the OFC (Old Farts Club) I have to remind myself I need to grow up. Nah .

 

Not battling czar but heres my view


Ok , focus on the two top edges of the plungers.


Just like the vw part which is tapered. the factory valve has an inner "ring" about 1-2 mm deeper. The outer rubber could be to emphazise the seal but not seal the outer surface area of the plunger.


I honestly believe the rubber is not for an outer seal because messing around with different spring tensions i have found that a little too much and the valve will not function. A rubber to metal seal around the outer edges would cause too much friction against the mechanism and i believe it would not let the valve operate smoothly if at all.

Instead of sealing with the taper maybe it seals flush?

 

I'd also like to add that the holes mentioned above are for releasing internal unit pressue and are not what vents the compressed air. The mechanism is a plunger/plug, the holes on the insides of the plunger vent internal unit pressure of the valve itself. You can replicate this by actuating the valve and feeling the air/vacuum move in and out of the valve itself.


I will be picking this up and removing the plunger to see/sim how it fits in the comp housing when i leave work





PS: if i had czar around me i would be a genius as to looking at every aspect of an answer for a question.


GOOD DISCUSSION!

 

SOMEONE TALK I NEED THOUGHTS I WANT TO KNOW lol


Im buying this today after work and will take a better look

 

I tend to agree with you Big. Looking at the stock DV it appears the holes vent some degree of pressure to the rear of the diaphram to assist the spring pressure and I'm sure the VAG operates the same. I also think the ring of the VAG against the machined port of the turbo provides an adaquate seal, at least I'm guessing it must on VW'S and Audi's. You know my VAG is installed, but unlike you, I'm not willing to pull it apart again. That is why you are the Spring F*****g Master. Good luck.