Garey Cooper

If any of you have experienced the infamous "honking" noise coming from your intake tract there have been some interesting developments.

First I have to say thank you to some posters and enthusiasts on another Turbo board.

It turns out that this noise has plagued Audi TT owners as well as Porsche 996 TT owners. And, the valves are identical. These are OEM'ed by Bosch for Porsche and Audi. The valves have diaphragms which are prone to tearing and/or harmonic flutter. The trick replacement being done by the Audi set is an after-market set of valves with piston actuators by one of two companies: Forge and Bailey.

Check this web site for some specific information: Stratmosphere Enthusiast Products. I don't know yet if anyone with a 996TT has done this replacement yet but I'm checking some sources. I am keeping any confidences so as not to unfairly malign any manufacturer or technician.

Has anyone posting to this board changed thier diverter valves from stock?

Garey Cooper

I just checked the link I posted and it did not work. I've evidently done something wrong. Try manually using this URL:http://www.stratmosphere.com/index.htm.

GLC

Flat6

A Diverter valve is a blow off valve correct? If so, is it possible to get the type that whistles put in this car... I really like the rally style blow off sound.

Flat6

Garey Cooper

Flat 6, I think those others vent to atmosphere. For environmental reasons the street type vent to recirculate the gases I believe. Although according to one person who conducted thier own test there was a different sound after the change-over.

fc-racer

I have just purchased one for my 91 911 Turbo to test. On the 944T, going from the upgraded 993 Compressor Bypass Valve (Porsche calls it Air Cutoff Valve) to an aftermarket metal valve resulted in 10hp and 15ft-lb torque to the wheels and significantly reduced lag, especially between shifts. The stock valve was leaking, even though it was new, sometimes it would not seat properly, even though the new 993 part is metal re-enforced.

I ordered the 007P which looks like a direct replacement. I will give objective and subjective information about its performance when it arrives and is installed.

On my racecar, I had to go with a really sturdy metal valve to stop boost leaking when we run 1.7bar. The plastic bosch valve would probably burst at those pressures!

Farzaan

Flat6

So... if anyone knows yet...

Do these result in any better performance (i.e. quicker response, more power?) for the 996TT? I'm interested in replacing these if they do.

Flat6

930 Turbo

Hi Guys,

I am based in the UK and have dealt with Baileys and Forge (both UK companies). If you need any parts from them, let me know as I may be able to get them cheaper.

Best regards,
Narinder

Fried Chicken Fred

There is another thread about this...

I learned from my Audi that you cannot use a blow off valve with a Bosch Motronic equipped car. The MAF relies on the Boost being there. I really wanted the "whoosh" sound!

I learned that if the boost is released to atmosphere it will cause the car to run rich.
I was told the rich is bad!

I was having issues with the sotck Bosch units. I was doing research and found an aftermarket replacement. I used a valve made by Bailey. I like it alot and never had a problem.

I have since sold the Audi and kept the valves. My dealer replaced one set on my 996 and they failed again. I put on the Bailey's and no more problems.

Here is the company I bought them from:
http://www.awe-tuning.com

Oak

Yes, I agree the Baileys are excellent DV's. I have used both Forge and Baileys, and the Baileys are far superior!

The Forge units came apart, the valves got stuck, needs constant relubing and rebuiding. A major PITA!

Go with the Bailey DV, beleive me I have used both. The Bailey have not had any issues. And are truly maintenance free.

Forge Motorsport

Hello
I heard about the discussion and thought I would introduce FORGE.

We manufacture many type of Diverter and Blow off valves for all cars.

We have a valve, the 007P that is a great option on any Bosch application.
The valves are serviceable and guarnteed for life .

The internal of the valve is piston driven, the piston is manufactured from aluminium.

The valves are avilable from our USA distributor www.stratmosphere.com
If you have any questions regarding our diverter /blow off valves , please contact me

Todd/A.W.E.

Greetings to rennlist readers:

We have recently been overrun with information requests regarding the Bailey Motorsport DV30 diverter valve we exclusively import into the US from the UK.

Please visit our website for basic information and pricing on this product:
http://www.awe-tuning.com/products/p...PPT=Drivetrain

Our experience is that the OEM Bosch valve, found on many Porsche/VW/Audi turbo applications, is not up to the task as handed to it by the factory, let alone if the boost is increased via chipping, etc.

We, and thousands of users around the world, have found the Bailey Motorsport unit to be the final fix for the problematic OEM valve.

Please contact us directly with any questions or comments.

Garey Cooper

Todd; Do you have installation instructions for the Twin Turbo available?

Todd/A.W.E.

Garey,

While we do have detailed install sheets for most of the cars we sell this valve for, we have not completed them for the 996TT yet.

However, the install is quite straight forward: remove OEM valves, and install Bailey Motorsport DV30 valves. No adjustments required, strictly plug-and-play. We even include new Zebra hose clamps for the install.

The DV30 was designed to be a direct replacement for the Bosch unit, and it is thus able to fit in the same confines with no interferences or modifications.

BG

I was on an Audi performance site <a href="http://www.hoppenmotorsport.com/bypass.htm" target="_blank">www.hoppenmotorsport.com/bypass.htm</a> and read that Bosch had recently upgraded their bypass valve to 1 they call their sport model for Audi's turbo motors and is supposedly a big improvement over the old one. The new part number is 06A145710N (don't know if that's a Bosch or Audi part #). I believe the valve Bosch supplies Audi and Porsche is the same so posssibly Bosch has resolved the problem with these units. If someone can cross reference Porsche's part #'s with Audi's and Bosch on an 02 996TT then maybe there is no longer a need to change these bypass valves.

Fried Chicken Fred

Nothing new...

I know for a fact that Audi, VW, and Porsche use the same valve. When I owned my S4 the dealer told me that they are on the 11th revision of the Bosch part.

You know what... It still fails.

I bought my Porsche and the stock ones failed. They put in the "sport model" version and they failed after 2 weeks.

I found out that the Bailey Valves from my S4 would fit on my car.

You know what.... No more issues.

Burn the Bosch!