Dump Valves

[QuattroFever]

Anyone know where i can get a DV that flutters like the old group B quattro's did and the pale blue 700 Bhp S2 built in finland (vid. on this forum).

Gota love that sound!!!!

[Greg_S]

I think the fluttering was from the turbo surging?

[Jon441cc]

Anyone know where i can get a DV that flutters like the old group B quattro's did and the pale blue 700 Bhp S2 built in finland (vid. on this forum).

Gota love that sound!!!!

my Dv made a strange sound with my old set-up ... nice but you do get sick of it

http://s88.photobucket.com/albums/k170/034quattro/?action=view&current=1stchatter.flv

You can't really hear it with my new set-up :mischeif:

http://s88.photobucket.com/albums/k170/034quattro/?action=view&current=GTI-chatter.flv

[QuattroFever]

it's not the usual ptooosh sound more of a fluttering whistle instead, only thing I can think, maybe a solenoid activated DV.

Watch the best of group b video on google and it's on the later group B quattro.

[Jon441cc]

http://videos.streetfire.net/categor...7e82d05992.htm

[A80Avant]

why did they say that Vas? i've just bought a 007 and i must admit, it is huuuge! i know the 006 is smaller and i'm now wondering whether i should have got that instead. will the 007 not operate properly unless linked to big turbo application maybe?

When my fiance went to the shop to buy the dump valve,the 007 looked smaller than the 006.Forge also told me that the 006 is better for the RS2 because the 007 is used in the RS4 biturbo engine which uses smaller turbos than the RS2.Thats all i know.I havent used the DV yet as my RS2 is engineless at the moment.Everything is being cleaned stripped and renewed...

[QuattroFever]

http://videos.streetfire.net/categor...7e82d05992.htm

thats the sound. I want it!!!!

[Ross]

I just fitted a Forge DV over the weekend... very easy with the maf + filter out, came with 3 springs and i fitted the blue which is aparrently 23-20psi. I'm making 21-22 (and more to come) and all seems fine.

I was getting a bit of the 'honking' sound on shifts, sounded pretty cool but I suspected the DV to be shot after reading this thread. I was also getting some occasional hesitation to build boost, she was still making full power at high rpms but it felt down on torque; I was often only seeing 1.3bar max. The car felt a little 'juddery' on lift-off too, and my usually consistent MPG dropped off about 10% I took the usual measures of checking hoses, tightening clips etc with minor improvement (one had come a little loose).

However, although I've only done 25 miles with the new DV, I can say that the honking is gone, she's making 1.5bar and held it in 3-5th and pulled like a f**king freight train up a good hill in top-gear at 6am this morning... from 3krpm. I was over 5k at the top!! Hard to explain, but I felt more 'confident' with the car as it just felt "on form" rather than a little lacking.

Project 400: The Final Phase is now underway

[1975DCS]

Don't use a dump valve - it confuses the ECU.

I have red something similar about this too, but I always thought that it was the otherway round that a diverter (like standard) is throwing back unmeasured air.
But to think of the only excuse people make into using a dumpvalve is the noise and the quicker release of air, so there is less change of stalling...

Can you please explain why it is better to use a diverter, as I have probably have misred or misunderstood... I also understand there are uprated diverter available?

[S2central.net]

Never confuse the sound of a dump valve from wastegate chatter and turbo stall !

The S2 was designed to run with a diverter valve that allows air to recirculate to the compressor inlet when the throttle is closed (lift off for gear change). This actually improves spool time and ensures the engine never intentionally leaks air that it worked so hard to ingest.

A dump valve is much less elegant - what it does is dump the remains of manifold pressure out to atmosphere during those gear changes... Thus ensuring a realistic rice-racer sound effect along the lines of 'piiissssshhhhhhh' - every time you change gear. Annoying, inefficient and guaranteed to increase spool time.

Lots of the old Gp B rally cars had no such valves - dump or diverter - they had that amazing sound due to wastegate chatter (modulating as the boost came) and of course turbo stall during gear changes when all that boost pressure couldn't be released and it actually slowed the turbo rotors actually causing damage to the turbo if used for long distances but those bad boys got rebuilt after every rally.

You pays your money, you takes your choice !


Paul

[Jas11n]

A recirc diverter is putting back "measured" air, not unmeasured air. The air has passed through the airbox, MAF, turbo then through the intercooler. On throttle shut off, the air is recirculated back in the MAF to turbo hose. If the measured air is released to atmosphere, then this means there is less air in the system than the ECU thought there was.
Some people find it fine to use a dump to atmosphere valve, but on the 3B S2 I drove with one, it felt very jerky and unresponsive immediately after a gear change.

[Jas11n]

Paul beat me to it

[1975DCS]

That's a very quick response guys! From both of you! So thank you for that!

So if I read correctly it is best to leave the inverter and NOT go for the atmospheric dumpvalve? But is it best to use the standard diverter (on my 3B)? Or is it better to use a different (Audi or aftermarket) diverter?

About the wonderful Group B era: Indeed I can't remember the Peugeot 205T16 or Ford RS 200 making a "blow off" noise... The only group B car that made such a noise was the Audi S1... But maybe this was not a dumpvalve noise at all...

Anyway nowadays you here all those powerfull Rallycross cars almost whistling continously, but maybe things are different for cars that don't use a airflow mass meter like a Cosworth? I really don't know to be honest...

Today me and some friends (mechanics) where watching some Rally video's because one of them suggested to make a seperate "atmospheric" wastegate "pipe" to get the fully rally (or even better S1) sound. And he said the noise you could here from the WRC's must have been from the wastegate and not from the dumpvalve since the WRC use anti-lag systems. But I said to him that even then there must be some way to get rid of unwanted boost if needed... Interesting but complicated stuff though... Well for me it is...

[Keeper of The Kitten]

...I said to him that even then there must be some way to get rid of unwanted boost...

Unwanted boost?

Did someone mention unwanted boost?!!

Can I have it please?!!!

__MDC__

[Robatron]

Never confuse the sound of a dump valve from wastegate chatter and turbo stall !

I thought I had wastegate chatter but in actual fact it was the turbo stalling. Luckily doug replaced my Diverter Valve and now I am much happier in the thought that the turbo shouldnt be blowing up anytime soon.