Diverter Valves

[CornersWell]

Talked with Stratmosphere, but they want $169 per valve. Kind of pricey, IMO. Any other brands that are more reasonably priced?

There are valves available on ebay at much lower prices ($69 per, IIRC), but has anyone had any experience with them?

Maybe I shouldn't be looking for a "deal" on these. Any thoughts?

CW

[AudiRS6JD]

Try looking up one through Shokan Audi...they usually have some RS6 parts available.

[malofquist]

can ask the dumb question of 'what does the diverter valve do' and 'why does it need replacing or upgrading'?

[CornersWell]

Anyone with better information or comments, please chime in.

As I understand it, the diverter valves allow the boost pressure generated by the turbo(s) to release when you go off boost. As you are aware, the turbo(s) compress air when the turbine propeller is driven off the exhaust gases, which is then "pushed" into the cylnders to generate more power in the ignition sequence. Once you generate the pressure, if you stop using it, the pressure needs to be relieved. I'm not sure if the damage can be done to the turbine itself (reverse operation?) or to the motor cylinders (additional pressure is dumped into the cylinders through the intake valves). Anyway, the diverter valve is essentially a diaphram that dumps/relieves the pressure.

The stock Bosch unit on the RS6 is a plastic and rubber affair that has failed in the stock configuration. Aftermarket valves are constructed from billet aluminum or a similar metal and thus have better tolerances and can withstand pressure better. While this is useful in the stock configuration, when you up the power or boost through an ECU chip, valve replacement is recommended.

CW

[malofquist]

Anyone with better information or comments, please chime in.

As I understand it, the diverter valves allow the boost pressure generated by the turbo(s) to release when you go off boost. As you are aware, the turbo(s) compress air when the turbine propeller is driven off the exhaust gases, which is then "pushed" into the cylnders to generate more power in the ignition sequence. Once you generate the pressure, if you stop using it, the pressure needs to be relieved. I'm not sure if the damage can be done to the turbine itself (reverse operation?) or to the motor cylinders (additional pressure is dumped into the cylinders through the intake valves). Anyway, the diverter valve is essentially a diaphram that dumps/relieves the pressure.

The stock Bosch unit on the RS6 is a plastic and rubber affair that has failed in the stock configuration. Aftermarket valves are constructed from billet aluminum or a similar metal and thus have better tolerances and can withstand pressure better. While this is useful in the stock configuration, when you up the power or boost through an ECU chip, valve replacement is recommended.

CW

why isn't it called a B.O.V.? like the rest of the boosted planet? is its functionality any different?

the word diverter could be used to describe the purpose of the waste gate or the blow-off valve.

[RS6-4dr911]

My understanding is that a BOV (Blow-off valve) or pop-off valve, and wastegate all function by releasing the excess boost pressure (when you shut the throttle or if the turbos overboost) to atmosphere. When that happens the energy stored in the pressurized inlet air is lost for good.

A diverter valve recirculates this high pressure air in a loop, saving the stored energy. When you get back on the throttle, presto, you have instant boost available without having to wait for the turbos to spool back up. Anyone care to augment this or correct it feel free.

My questions are:

1. What indicates that the current valves are not doing their job (is there a slow degradation or do they only fail catastrophically/binary mode - i.e. they work or they don't)?

2. If you replace a stock valve with the Stratmosphere or others, will you notice a difference in driveability (since I assume there is no peak power increase) or is it only a reliability upgrade?

[malofquist]

this is slightly off topic, but my RS6 seems slow :(. typically, do audi dealerships have dynos?

[CornersWell]

Most Audi dealers don't have their own dyno. I suspect you'll need to find a tuner shop or race shop to have the car dyno'd.

Good to know about the diverter valve not "dumping", but "preserving", the energy.

Can't comment further on the telltale signs of a stock diverter valve failure. Perhaps no boost? Or, perhaps engine failure? Also, can't say as to whether it's a gradual or instant failure. Anyone with more info?

As far as my interest in replacement goes, I've purchased a set of Dalhback air intakes, and with the additional air coming in, I'm wondering if they're a good saftey modification. Again, I've mostly heard of these mods in conjunction with a power chip. It's entirely possible that the stock valves are satisfactory. Just considering an improvement.

CW

[skiwi]

My understanding is that a BOV (Blow-off valve) or pop-off valve, and wastegate all function by releasing the excess boost pressure (when you shut the throttle or if the turbos overboost) to atmosphere. When that happens the energy stored in the pressurized inlet air is lost for good.

A diverter valve recirculates this high pressure air in a loop, saving the stored energy. When you get back on the throttle, presto, you have instant boost available without having to wait for the turbos to spool back up. Anyone care to augment this or correct it feel free.



correct - the audi design "diverts" the excess boost created in off-throttle conditions, back into the turbo meaning that:

1) the turbo keeps spinning and doesn't stall
2) there is more boost pressure in the intake system than there would be otherwise

end result is smoother and better operation. btw they do not control boost pressure as some seen to think - that is done by the wastegate and the wastgate frequency valve....

*but* you do miss the "whoosh" sound so beloved of the rice racers....

[CornersWell]

So, then, the real benefit of the valves is to keep the boost "on tap"?

Why didn't Stratmosphere just tell me that?!

CW

[skiwi]

the valves can deteriorate and leak with age/heat which results in reduced boost pressure. other claims are for later opening (meaning holding pressure longer), before diverting. also the oem valves (bosch) are plastic while the after-market valves are often metal.

[Boosted-Bora]

cornerswell. i have the dahlback air intakes as you know i also have the dahlback diverter valves and the made a huge difference i had the intakes at one time and they mad good power and cut lag time by some but when i got the diverters the throttle response increased significantly

[SpinEcho]

I have replaced my DV's with the Stratmosphere units.

The OEM units failed on my car repeatedly with track use (prolonged boost!) with symptoms as follows: intermittent loss of power, getting worse and more frequent, with a loud whistling noise from under the hood.

The failure was proving downright dangerous as it was unpredictable - imagine: pull out to pass on a 2 lane highway, get part way past the other car, then suddenly feel like you have 200 hp not 450 !

So far so good with the aftermarket units...

[uberalles]

i have a pair of black bailey's diverter valves for sale if you're interested. i'm looking for 210 shipped.

edit: sorry for hawking my wares in my first post. i'm an A6 driver and i've been lurking the forum for a month or so looking for an rs6 exhaust.

[Rich_C]

I'm having APR R1 recirc valves fitted this week which might be an alternative to consider. Why? - well after 4.5 years of hard work I think the factory Bosch ones are ready to be put out to pasture for a well deserved rest. Why did I choose APR ones? - well personally I liked the maintenance free aspect of the diaphragm design compared to the piston type - details below - $159 each.

Rich.

http://www.goapr.com/Audi/products/r1.html

Highlights of the APR R1 Diverter Valve Include:

Diaphragm-Based Valve
High-Temperature, Nomex-Reinforced Material for Extreme Durability
Zero-Friction
No Sticky O-Rings to Maintain and Grease
No Pistons to get Stuck
Consistent Performance Year Round
Flow-Optimized, Investment-Cast Main Housing
Stainless Steel Vacuum Fitting
Zero-Maintenance Design
Built with Finest Materials and Surface Treatments
Fully Machined and Assembled at APR Headquarters in the United States for Optimal Quality Control

The APR R1 diverter valve was designed to be the ultimate solution to the problem of unreliable factory and aftermarket diverter valves and to be the leader in performance. Although most are of good design, factory diverter valves are built in a very conscious manner and the materials and overall life and reliability suffer. For the performance enthusiast, the diverter valve is an important component whose proper operation is paramount to optimal engine operation.

Enter the R1: APR’s R1 diverter valve addresses all of the reliability problems of the factory-supplied diverter valves and aftermarket replacements and takes performance to the next level. The R1 is a diaphragm-based valve. A diaphragm is the best option for a diverter valve for several reasons. First off, a diaphragm has negligible friction. Piston-based valves have considerable friction from the piston, o-ring, and bore assembly. The lower friction R1 diaphragm equates to faster response and better overall performance. Secondly, diaphragms do not require the periodic greasing that piston-based valves do. Piston-based valves must be qreased periodically (usually every year or sooner), requiring removing the valve from the car, disassembling and reassembling the valve. The APR R1 was designed to be maintenance free for the life of the product. Thirdly, a diaphragm based valve will never have a stuck piston. Piston-based valves periodically incur stuck pistons (especially if the required maintenance schedules are not followed.) Due to the lack of a piston, the APR R1 solves this problem.

The R1 is designed for optimal performance. The main body of the valve is investment cast in an aluminum alloy. By utilizing this casting process in lieu of a more conventional machining process, APR was able to optimize the internal geometry of the valve to provide the ultimate in flow performance. This geometry cannot be created utilizing conventional machining. As such, the APR R1 has much better flow characteristics than other diverter valves. Combined with the low friction diaphragm assembly, this equates to a valve that is truly a performance leader.

The materials used in the R1 are standard setting. The diaphragm is created out of high temperature material and incorporates a Nomex fabric reinforcement layer for enhanced durability and a diaphragm that will never tear. The alloy main body is finish machined at APR and receives a multilayer corrosion resistant and cosmetic enhancing finish. All machining and final assembly takes place at APR headquarters in the United States for optimal quality control and consistency.

[CornersWell]

Uberalles,

PM sent.

CW

[gjg]

I have to stop reading these threats - last night (hot day, 39 C, 250 km run, mostly on a-bahn, bit fast) lost engine power, there is a slight slooosh sound every time rpm would increase and car goes to limp mode. It behaves almost like busted turbo hose on AAN engine but it does that right above idle. So limped home.

1 Fault Found:
17743 - Engine Torque Monitor 2: Control Limit Exceeded
P1335 - 008 - Implausible Signal - Intermittent

this is the only code found in the system.

Any ideas before I take it to the stealer and get something replaced at the cost of new engine?

[parkertseng]

How about the diverter valve from milltek website? By the way, the DV Audi used for S3 is better than RS6,also from Bosch, because S3 is high boost setting? Personally I would choose the one from Milltek. What do you guy say? Wondering how much will they be?

[Rich_C]

I have spoken to a tuning house in the UK that fit Milltek hyperboost valves as standard when remapping regardless of stage. They were probably second choice but decided on APR as they offered the maintenance free diaphragm recirc valve - the Milltek version is a traditional piston design ... here's info from Millteks website for anyone interested ...

Milltek Hyperboost HXC Compact Diverter Valves - http://www.millteksport.com/hyperboost.cfm

Replaces the factory-fit Bosch diverter valve to provide a faster response and more reliable operation. Reduces lag and sharpens throttle-response - meaning faster acceleration and improved driveability. Same width as your factory Bosch valve and only 20% taller. Fits under engine covers for VWs and even in the Porsche Twin Turbo.

The Hyperboost valve reduces turbo lag as it recovers faster when you 'hit the throttle' reduced lag = faster acceleration.
Throttle modulation is smoother and feels more accurate under your foot.
These valves also perform accurately and reliably time and time again, even in the most extreme conditions.
Inadequate/defective standard valves have extended lag, loss of boost, sluggish throttle response. A HyperBoost valve can clear up the previously mentioned problems and offers reliable action, time and time again. If your car has been chipped, a HyperBoost valve will optimise the performance benefits.

New HX Compact features that make the difference in your ride:

Our highest boost rated valve ever with increased internal rate.
Lightning response when you want boost, our fastest.
Our lightest internals ever for the quickest action yet.
X-type heat sinks to keep cool.
No bunk diaphragms to worry about tearing.
Ultra competition grade.
Unique features with the HyperBoost valve:

TeflonT impregnated piston for the most accurate and consistent action available while promoting long life.
Utilizes larger VitonTM brand o-rings for increased piston seal to insure leak-proof operation.
Internal parts are lubricated with Mobil 1TM synthetic grease, the best you can buy.
Connection nozzles are machined to OEM/BoschTM dimensions.
O-ring sealed cap for positive locking and a leak-proof seal.
Hyperboost valves come with:

1 Hyperboost HX Compact Diverter Valve in Silver.
3 Replacement Jubilee Hose Clips (2 large and 1 small).
Quality stainless steel hose clamps with rolled-edge for hose safety.
Installation instructions for Audi TT or Audi S4 (TT install is similar for all single turbo installs).
Lifetime warranty (proof of purchase required).

[skiwi]

1 Fault Found:
17743 - Engine Torque Monitor 2: Control Limit Exceeded
P1335 - 008 - Implausible Signal - Intermittent

this is the only code found in the system.

Any ideas before I take it to the stealer and get something replaced at the cost of new engine?

hopefully as simple as a leaking hose to your n75 valve. it not, could be expensive...

[gjg]

hopefully as simple as a leaking hose to your n75 valve. it not, could be expensive...

I will taky it to my friend garage and look the hoses first .... it definitely has airleak somewhere, the diverter valves seems to be ok ....

[parkertseng]

so the vavle from APR is better form Millteck? How about the stock one form S3? Spoken to my friend (dealership Sportec in Taiwan), he said I can use the dv from the stock one from and S3! Can't remember the model number he said, Bosch T70? Since it is regulaing the pressure, can it be adjust? for future modification. What is the best choice for me? with just chipped and bigger intercooler form Sportec?

[gjg]

I will taky it to my friend garage and look the hoses first .... it definitely has airleak somewhere, the diverter valves seems to be ok ....

hose slipped - left side, quick fix, no charge, back in business :thumb: