MichaelTT

By now the issue of the OEM DV problems are documented ad nauseum, but two things continued to bothered me... 1. the comments about 'reversing' the DVs and yet they would 'function' in either position, and 2. I really did not have a technical grasp on HOW the DV function and IF you could reverse and still have DV function. I tend to not like being in the dark...so my search for answers and this is MY opinion on these issues, but are conclusions based on discussions with Audi, AWE and reviewing Bailey tech info.

First is the basic design of a DV and how if should function...thus my simplistic drawing. The valve consists of a vacuum hose connection which activates the opening/closing of the diaphragm (OEM DV) or a piston (Bailey DV), a high-pressure connection which comes from the turbo boost side and a low pressure connection which is a return back to the turbo. The basic concept is as the turbo spools up (increase boost) the valve is in the closed position and all turbo boost goes to the intake manifold, but as you lift off the accelerator (as in shifting) the vacuum hose is activated 'sucking' the piston upwards thus opening the high pressure side to the low pressure side and 'diverting' boost back to the turbo...in a sense blowing its own pressure back to keep the turbo spinning aka 'spooled up' thus minimizing 'turbo lag'.

· How can you 'reverse valve' and it still work? The answer is you can reverse valve since the simple piston design (Bailey Valve) allows for high to low pressure to go in either direction...high pressure can hit the side of the piston or the bottom of the piston and when vacuum opens piston the pressure will seek its way from high to low pressure areas.

· OEM DVs are constructed differently...they use a diaphragm...and they can not have high pressure coming in above diaphragm (with piston the pressure would be hitting the side wall of piston and thus blocked) since as the diaphragm is lifting (vacuum activated) the pressure side would be pushing and two things happen...diaphragm vibrates from two opposing forces and thus 'HONKKKKKK' and lifting action is erratic and thus surginess/loss of power.

· An engineering conclusion (not my own but those who design DVs)...the base (bottom) of the piston should be facing the pressure side of the turbo system...see notations on drawing.

· Conclusion (mine and a few others only)...the OEM DVs have been installed 'reversed' to start with...look at the OEM DV, how it was installed, reference the following photos and my comments how the 'honking' noise is made. So when Audi said 'reverse' DV actually you would be 'unreversing' DV and thus the honking would lessen for a period of time (remember the OEM 'E' and 'G' valves have other deficiencies so they could not correct all problems.

· This is where it's interesting... Bailey/AWE used the positioning of the OEM DV for the instructions on how to install the Bailey and now that the understanding that the OEM valve was installed 'reversed' the Bailey installs are 'reversed'. The series of photos I have included shows the original Bailey install and the revised install. First, the Bailey, due to its superior design, can be installed in either direction without harming engine (K04 turbo max pressure output is about 1 bar and Bailey is rated at a max capacity of 4 bar)...the difference of installing 'reversed' (as I and most have done...see pics for reference) and 'un-reversed' is the noticeable elimination of the 'Darth Vader' breathing sound. I agreed to try my 225 in this experiment...Todd (AWE) and I discussed this in detail. I switched {un-reversed) Bailey (a 10 minute job at best...and yes LarryTT... did not have to remove strut brace bar) and the very noticeable Vader sound went to a simple brief whisp sound. Nothing else changed...same 'no surginess', regain of power, just less noise when the valve is activated.

· When you do this 'reversing' you DO NOT have to disconnect ECU...the change corrects noises not performance on the Bailey.

I have posted a series of pictures that hopefully shows graphically what I have been trying to explain...

<img src="http://pictureposter.audiworld.com/AudiWorldPics/2000/dvdrawing.jpg">
<img src="http://pictureposter.audiworld.com/AudiWorldPics/2000/Originalsideview.jpg">
<img src=http://pictureposter.audiworld.com/AudiWorldPics/2000/original.jpg>
<img src=http://pictureposter.audiworld.com/AudiWorldPics/2000/correct.jpg>
<img src=http://pictureposter.audiworld.com/AudiWorldPics/2000/realignhose.jpg><p><img SRC="http://pictureposter.audiworld.com/AudiWorldPics/2000/annapolissig.jpg" BORDER=0>

2001 Amulet Red 225TTQC
AMULETT

Larrytt

Will Todd be send out an updated sheet of instructions or will he be sending out an e-mail or posting it on his website?

What are the ramifications of leaving the Bailey "reversed" now? I understand the Bailey is a piston and works on vacuum and everything that you explained ... but can you answer one thing for me?

Why does the Bailey make a DarTTh noise if installed in reverse? What is causing the noise? Is the piston hollow on the backside and air is hitting this area and causing the noise?

Thanks for the info.

By the way. I was not trying to bust your chops about telling everyone to skip removing the strut brace, I just knew it was not necessary and just made the job of R&R'ing the valve a major pain in the a$$. Most of the people on here were skttish enough about just doing the valve, I didn't see any need for them to remove the brace also!

Will you and Ellen be making the trip north on Sept 9th?

VAP

you must've painted your strut bar yellow. I like... can ya back up and give me another shot of the entire engine bay with strut bar for ooooh-ahhhh factor? Always liked yellow/red. I was thinking of chroming mine over the winter as thats about the only accent that suits black. Or brushed finish electro-plating like on the fuel-filler door.

MichaelTT

conclusion is the turbo pressurized air if entering the Bailey from the side of the piston
and piston lifts there is turbulence created as the air 'rolls' around the side of the piston
into the lower chamber...the opposite scenario is the pressurized air entering the bottom
of the piston is held in place and as piston lifts it immediately exits to the low pressure
side thus the brief 'whisp' sound.
Todd said that AWE will be modifying the info about the install...beyond that he didn't
comment.

Concerning strut brace removal...since I was one of the first 'experimenters' the removal
made sense, but as you pointed out it was not really necessary and thus the process
works...trial/error and a better mouse trap

The Sept date looks like a go...balancing family obligations in Texas and trip. Thanks for the invite!<p><img SRC="http://pictureposter.audiworld.com/AudiWorldPics/2000/annapolissig.jpg" BORDER=0>

2001 Amulet Red 225TTQC
AMULETT

Larrytt

Will you be coming in 1 or 2 cars?

john s

Input & exhaust are on same side of diaphragm, but surface area is different. Valve is held in position by spring, excess pressure will cause opening. Force is proportional to pressure & area. Net force is spring force – (boost pressure (abs.) x boost area – vacuum pressure (abs.) x vacuum area). Area exposed to boost & area exposed to vacuum need to be sized properly for proper operation in overboost protection, spooldown control and fuel economization during cruise. Boost pressure to side of piston gives no overboost protection. Diagram shows same area for boost & vacuum, not correct for 2 bar system. Diaphragm type should have less inertia than piston type, giving better protection & spooldown control. Problem is with uncontrolled movement at small valve openings. High inertia causes less of a problem in this case.

Chad D

On that note, does anyone know where to get better looking strut caps?

Lone Starr (Ivan)

Wow. I didn't follow that at all. You?

MichaelTT

<center><img src="http://pictureposter.audiworld.com/AudiWorldPics/2000/DV%20and%20Brace%20Overview%2013.jpg"></center><p><p><img SRC="http://pictureposter.audiworld.com/AudiWorldPics/2000/annapolissig.jpg" BORDER=0>

2001 Amulet Red 225TTQC
AMULETT

Lone Starr (Ivan)

HOW IN THE HELL DO YOU KEEP YOUR ENGINE COMPARTMENT THAT CLEAN!?

Beautiful!