Dump valve

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S3_nick

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hi guys im after some help here because im really not winning i have a atmospheric dump valve on my car at the moment but i dont like its sound so i want to replace it and yes i know they arnt spose to have them on but it works fine at the moment with one on, so first i brought a bailey twin piston dump valve the car was barely driveable on it so i put the standard one back on then i got a LMA uprated diaphram dump valve makes the car idle funny and cut out so then i thought ahh i strip my one down and see what type it is an its a single piston type so i bought an LMA single piston one and low and behold it makes the car idle funny and cut out if theres any one out there running out and your having no problems could you tell me what type and make to get please.

Thanks Nick
 
but thats a recirc il loose the blow off sound if had one of them on borrowed it off my mates tt didnt get a peep out of it so i took it off
 
1.8t's aren't designed to use atmos valves... you want the engine to run properly then you need to use a DV... its as simple as that...

If you want 'noise' then a cone filter and a remap (more boost pressure = more air to release) will do it and you engine will still run fine... atmos valves are a big no no on VAG engines... simples..

<tuffty/>
 
ive got a cone filter to go on it and its already remapped so will i get a chattering when the boost is let off?
 
...just to validate why a DV is required...

1.8t's use a closed intake system (as do most modern engines) and the air is metered using the MAF sensor so the ECU knows how much duty cycle it needs on the injectors to get the right AFR for that air at that time... when you let off the throttle and the air is 'dumped' back through the DV into the intake system as the air volume has already ready been measured and the ECU is happy and knows how to deal with it...

If that air is 'dumped' to atmosphere then the charge system has less air than the ECU thinks it has and makes the AFR too rich causing hesitation, poor idling and potentially stalling the engine..

Atmos dump valves can also cause small leaks which lead to poor idling and poor engine response etc..

They are designed to have a DV...

<tuffty/>
 
Last edited:
S3_nick said:
ive got a cone filter to go on it and its already remapped so will i get a chattering when the boost is let off?
Click to expand...

If you are getting chattering then it may not be dumping at all and stalling the compressor which is very bad.... it can lead to a broken turbo...

<tuffty/>
 
The dump valve/recirculating valve is recirculating the air back into the intake system after the MAF so surely the ECU hasn't registered this additional volume of air so in theory will be more lean unless additional fueling is logged into the map to compensate for this extra air?
 
I have a stage 1 remap with a Forge 007P diverter vavle (standard airbox/filter), and it really isnt as quiet as people make out.

I can easily hear it diverting the air; both with the windows up and down.

I heard a Astra VXR with a dump valve on today, which sounded loud, but quite lame and lifeless compared to the sound i get from mine. Its like a long and 'boosty' sound, i love it!!
 
Andy123 said:
The dump valve/recirculating valve is recirculating the air back into the intake system after the MAF so surely the ECU hasn't registered this additional volume of air so in theory will be more lean unless additional fueling is logged into the map to compensate for this extra air?
Click to expand...

There is no additional volume of air.... its a closed system... it recirculates the 'metered' air already in the intake system...

<tuffty/>
 
mate i have a carbonio cold air intake and a forge 007p diverter valve and i get a nice loud whoosh. It makes a nice roaring sound also when i put my foot down.

Your better off with one of those, any induction kit will do a similar sound though. Dont break your turbo and your engine just because you want a whoosh sound. Do it properly.
 
My standard item is a hell of a lot louder since adding a Green Cotton Filter...

TBH, I prefer the sound of the car going forwards... not taking my foot of the pedal...
 
JD09 said:
My standard item is a hell of a lot louder since adding a Green Cotton Filter...

TBH, I prefer the sound of the car going forwards... not taking my foot of the pedal...
Click to expand...

This ^^^

Blow off sounds silly on a VAG engine...Kind of thing you would expect to see/hear on a Chaved out scooby.
As others have said, if you want the 'Woosh' noise theres ways of getting it wast using a 007P.... Change the TIP, N75 Bypass, Cone Filter, Remap etc.
 
ive put my mates forge DV on il see what i think to it on the way to work tomorrow as ive not had it on since ive done my exhaust and cooler and ive got to put my tip on at the weekend so we will see
 
rite tips on filters on dv's on and ye your rite i do get abit of a noise so quite happy with it and it dose drive alot better thanks for the help can some one tell me about this n75 by-pass?
 
I'm running a Forge 007p and Jetex cone filter with a stage 1 map. Also done the N249 bypass which made it sharper and louder. Sounds really well for a recirc dv! You can easily hear it outside if you let off at the right time. Boost up until 3k revs and you hear a smart whoosh out of it!
 
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