Diverter valve 2.0tsi

Cmw9

Registered User
Im looking for a new diverter valve for my 2011 a3 (newer tsi engine) before a remap. Im looking at this forge one but im abit confused because it looks hollow. I want this one because it will more noise because its atmospheric but the other one ive looked at has the piston in the middle, bit confused. Has anyone got any experience with this?
 

Cmw9

Registered User
Forgot the picture
360e1c6309e2d91e950182074735f9a6.jpg
 

Murton

Member
VCDS Map User
The piston seals a hole between the air intake and the boost output of the turbo. When you lift off the throttle the ECU pulls back the piston to allow the boost to circulate back into the air intake side (so the air effectivly just goes round and round the turbo until it spins down). The centre part of the picture is only plugging the hole permanently. If it were hollow then it would suck in air from the outside bypassing the air filter. The diverter valve is naturally sprung to seal the hole with the pressure difference helping to keep it sealed. The ECU signals the solenoid to pull the piston back.
You may prefer the sound of the dump valve but the solenoid one gives you more tuning flexibility without having to change the release pressure of the dump valve every time.
 

Cmw9

Registered User
Cheers for that. So something like this would be better? How do you change the release pressure for this forge one?
 

Murton

Member
VCDS Map User
You might not be able to. If you want to run higher boost you might have to replace it with one of a higher rating.

There is also a wastegate on the input to the turbo which lests the exhaust bypass the turbo when you are off throttle and this is what normally regulates the boost pressure I believe. The diverter valve only being used to stop excess pressure building up when you suddenly come off throttle or change up a gear. That is only my understanding and I might be wrong.

I don't know what happens when you drive normally with the turbo off. There might be enough exhaust going through it to turn it slowly so it does not offer any resistance to the air intake. However if the ECU has the diverter valve open in this scenario then having the hole permantly plugged will restrict the airflow (but only when you don't really need it) which might impact things.

Personally I would speak to whoever you plan to do the remap and get their opinion.
 

Murton

Member
VCDS Map User
Also consider what happens when you come off the throttle or change up a gear. The VAG cars do not have an intake pressure sensor but instead work it out by using a combination of the engine speed and the air mass sensor. Changing the setup to vent to the outside will cause the ECU to see more air being pulled in and it will think there is more boost then there actually is and you might get things like a bit of hesitation when you suddenly accelerate again.

I can just imagine it causing issues as the car is not setup to work with that sort of system.
 

Murton

Member
VCDS Map User
Maybe the blow off dump value is set at a much higher pressure than normal boost. Normally dump valves are to stop excess pressure not because it affects the engine but because it can try to stall the turbo which is not good for it. In this case you will still have some high boost slowing down the turbo when you change up a gear. With the original part the turbo is almost free spinning so less turbo lag when you put your foot down again.

I don't know how much effect this will actually cause as I am not a turbo expert by any means but it does seem that the original system is technically superior.
 

JJ.Foulds

Registered User
im soo confused with that you guys are talking about!
the item in the picture is just a blow off spacer. Its fitted inbetween the current OEM recirc valve and its holder and all it does it causes an amount of the air (maybe half) to exit the small holes in the side of it and any remaining go back through the standard recirc system.

It doesn't effect the current recirc valve at all, it will act in exactly the same way.

I have the exact spacer fitted on my car, HOWEVER it is recommended that you DONT use any blow off valves with VAG engines, you will have a slower spool up time when slamming the pedal and changing gears, but i like the PSSSSSSST, its fun, so compromise.
 

Cmw9

Registered User
How much does it affect the lag on yours? Mines dsg so i prob wouldnt feel it between shifts?
 

nil538

Registered User
As said that not a diverter valve it's just forge spacer you need to buy the forge dump valve kit witch is about £199 to replace your old exceeding diverter valve and upgrade to a forge one mate
 

JJ.Foulds

Registered User
How much does it affect the lag on yours? Mines dsg so i prob wouldnt feel it between shifts?

I mean, im sure i would notice a slight difference if i took it out, but end of the day, im not trying to beat the 1/4 mile, with normal driving theres no chance of noticing big difference. Plus i love the PSSSSSSSTTTTTTT! especially in multistory car parks...
 

syko

Registered User
JJ have you a video of the sound at all as I would like a little dump sound from mine but always thought it would be silly loud and cause issues
 

Dean_T

Registered User
If you want a bit more noise then do it properly and fit a CAI kit.

Should be better for the remap too ;)
 

S3_Jacko

Registered User
I'd rather have a cai than this all day long... I had a blow off on my old old A3... After 3 months, hated it with a passion... Pain in the erse to fit to K03 cars too...

I had the A3 2.0T quattro and the power loss from it was terrbile...

Keep the recirc, uprate the dv to the dv+ or something (they are meant to work better on K03s) and fit a loud cai.... The sound from the atmospheric dump valve is seriously sh!t and works on a negative way on your engine.. All my opinion and experience of course..

But its lose lose and would never recommend to anyone to get 1
 

S3_Jacko

Registered User
Sounds like a bus...

 
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