I'm still confused as to what direction I should go with.

Audi installs it sideways (side faces the high pressure) Turbo5 (Clark) recommends sideways installation for their valve as well.

Volvo installs it straight (bottom faces the high pressure) AWE recommends this installation for their valve as well. Their argument is that "the escaping boost through the valve works to push the internal piston open faster."

Who's right?

 

I'm confused too.

I know most A4s have the bypass sideways, but mine was straight. APR recommends that I switch mine to make it sideways like their stage 3 car.

Rich

 

The Bosch style valves should be installed with the side to the boost. They have a low pres spring and are designed to go this way. Every turbo porsche and Audi I have ever seen comes with the valve this way. If they are installed witht he boost on the bottom they can and will leak. In addition you may blow the diaphram open as it was not designed to take that much pressure on it.

With after market units like the bailey or the PES valve you should install them the oposite direction as per the instructions. Those valves count on differential pres on both sides of the valve. They use a heavy spring and some like the PES unit are adjustable.

For example. On the PES valve you receive spacers for the spring. Each spacer ups the boost level by .8psi. Read the fallowing to get an understanding:

I can not tell you how many washers you will need to install for optimal
performance, since this does vary from car to car. However, here is some
technical information that should help. Lets assume you have 20psi of boost.

The differential pressure across the valve that is required to open the
valve is 4.4 psi. Therefore, once the pressure differential is more that
4.4 psi, the valve starts to open. If this is happening before you reach 20
psi, your boost will be limited and you need to add packer washers. Each
washer should increase the differential pressure by approximately 0.8 psi.
However, as you increase the boost pressure the pressure drop thru the
intercooler piping and throttle body may also go up. Therefore, you may not
get the full 0.8 psi for each washer.

For example, if you find the valve is opening at 17 psi. You would add four
(4) washers and therefore increase the spring tension to hold up to 17 + 3.2
= 20.2 psi. However, because of the increased boost pressure, the pressure
drop thru the intake piping and throttle body housing may go up by say 0.5
psi. That is, from 4.4 psi to 4.9 psi. Therefore, the actual pressure at
which the valve will start to open at will be 17+ 3.2 - 0.5 = 19.7 psi.
I'd recommend starting with no washers and if the valve cracks before 20
psi, add to appropriate number of washers you need to get up to 20psi. If
it is still not quite there, add one more washer. (The washers simply are
added by simply unscrewing the cap, removing the spring, and dropping the
washers in the bottom of the piston).

In testing the PES valve we have found that 1-3 washers is where you need to be depending on your chip and mods.

I am not sure how the bailey valve works so I can comment on it.

Hope this helps.

Clark

 

I would try mount the bpv both ways and montior the boost gauge. And see which one hold up the higher boost and also compare to see which one give you better between shift boost recover time .So far I mount the bosch bpv bottom to high boost side and notice no problem with boost leak.I am also question why so many stock bpv failure with low mile on pre y2k car. And audi change the bpv mount from y2k on car .

 

and have to say that there is very little perceptible difference between the two techniques. The Bailey opens at pretty much stock vac levels...so putting it in the factory way should result in identical valve actuation behavior...BTW - I'm not just talking out my *** Frank, Emil SCTT and El Cheng and I measured several valves...there was the TurboSmart AU valve which is basically the PES...Emil has that on his TT...I don't remember them measuring that one...then the Bailey...the Stock TT valve...Stock 1.8T valve...Stock S4 valve...Forge Diaphragm Valve and Finally the Forge Piston valve...all of the Forge Valves were tested with 3 different spring stiffnesses. Anyhow the point was that measurement was fairly scientific...so I feel safe saying the Bailey is pretty close to stock if my memory serves me. So putting it in the factory way should be totally safe.

You mention that air escaping through the valve will force it open faster...well by the same token the boost on the valve face is working against the spring to unseat the valve...then you've got counter boost through the control port trying to close it...the net result...under boost the only thing holding the valve closed is the spring and the spring alone...it could leak as the other side or the valve body is under vac as it faces the intake of the turbocharger.

In the Audi way it would seem to be the least leak prone...pressure against the side of the valve...pressure against the valve on the control port...but this time the face of the valve is being sucked down by the turbo intake vac...effectively holding it shut preventing leaks...so it would seem this would hold the highest pressure of the two arrangements. If you wanna do something trick try putting in two valves in parallel if you're concerned about venting pressure ASAP...you'll need to make some custom pipes though.

Regards,

James R.

2001 A4 1.8TQMSXP (Oettinger Pedals, Oettinger RE's 17x8 Yoko AVS Sports 225/45/R17, Euro Xenon Housings, Bailey BPV, Turbo5 Intake and RS4 Grille)

 

what was the final conclusion on the diverter valve testing?

Could you provide us with a little synopsis on the characteristics of each valve. How did the diffrent springs in the forge valve affect performance?

Thanks
DK

 

I swapped it around. I DID notice two things:

1. In the "sideways" orientation, the off throttle boost transition was quicker; ie it seemed to "clamp down" qicker and harder.

2. intake manifold pressurization noise seemed quieter in the "sideways" orientation.

Just my observation.

 

Just one thing.When engine under boost .There is pressure on both sides of valve.But just not as great as pressure direct from ic pipe.Due to restriction at intake manifold pressure drop and size of vaccume hose to top of valve.But there is pressure on top of valve to help keep it shut besides the spring alone.Put it in other way .The pressure on both sides of valve is very much same.But due to size of pumping. The pressure volume is different.And that is different spring rate come in to fine tune for best preformance

 

Ohh, OK well I didn't actually put all of those valves on my car.

Basically Stratmosphere wanted to carry the Forge line of valves but they all needed to be tested. One of the more rudimentary tests was to make a determination as to weather or not the valves were even close to stock in terms of VAC rating...because if they're too far off they will lag and could potentially cause turbo stall and potentially worse (read, damage).

Frank tried several of the diaphragm valves on his S4 (multiple springs) and you should talk to him about his opinion of those. He would have tried the piston but they didn't fit, I think that has been resolved.

Anyhow...I was going to try the Forge Piston Dump Valve...but was not very happy with the somewhat sticky valve motion...it kind jerks up and down...the Bailey is much smoother in actuation.

Anyhow...I settled on the Bailey Valve installed in the factory position...I feel that this the probably not the most responsive positioning of the valve...but it is the least leak prone position.

Regards,

James R.

2001 A4 1.8TQMSXP (Oettinger Pedals, Oettinger RE's 17x8 Yoko AVS Sports 225/45/R17, Euro Xenon Housings, Bailey BPV, Turbo5 Intake and RS4 Grille)

 

Well you'll notice I mentioned that...there is equal pressure on the valve face and pressure port sides. I didn't go so far as to include the pressure drop from the plubing and IC...so the situation is even worse than I originally mentioned. Cause if you've got pressure X on the face of the valve on the turbo outlet side then you've got pressure X-Pressure drop on the other side of the valve through the control port...which means now there is even less than the spring force holding it closed...

So in reality your reply only serves to further reinforce my assertion that the stock Audi way is the proper orientation for those reasons I stated earlier. Was that your intent?

Regards,

James R.

2001 A4 1.8TQMSXP (Oettinger Pedals, Oettinger RE's 17x8 Yoko AVS Sports 225/45/R17, Euro Xenon Housings, Bailey BPV, Turbo5 Intake and RS4 Grille)