dump valve selection
Turbo Mini Forums

hi guys im in the process of building a turbo engine over the next couple of months but im wanting to avoid the usual dump valve woosh noise lol if possible that is! Im going to be hoping for the 170bhp mark! Is there one on the market i could have that would be suitable? i have heard some say a recirculating dump valve is quiet but i was speaking to someone else who had one on a car i had been in and it was far from quiet!
any advice on what you have is great

i have a bosch recirculating one - you cant hear it. was only 99p from ebay too

i have a Bosch recirc on my audi S2 (standard fitment) and with standard air box very quiet...
but with an open filter very loud lol..

hmm i have got one of the plastic bosch ones off a saab will this do?

Probably

thats what i use...

It may not be suitable for high boost as I've read somewhere on here?

Ah i see. Thats good to know, i think mine was a bit leaky (may have been a bit worn) i was running 1bar of boost

My plastic Saab one leaks too, on boost over 12psi.

Can we have the part number of the "better" one please, Colin ?.

Are you both sure you have yours plumbed in the correct way?







Uprated valve commonly known as 710N or 114. This is the one I have. There is apparently another, the Bosch 110 (bosch 110 sport?)

Bosch # 0 280 142 114 or VAG # 06A145710N

I was under the impression that the port oposite the small inlet manifold take off is connected the the plenum, and the side port connects back into the inlet. Am i wrong? This is how i did it on my car, it can be heard 'dumping' when you give it some stick.

Still a question about the dump(bypass)valve of a supercharged engine. Is there something so I could manage my goal of pressure?
I dont want too much pressure because of dailydriver.

Good info, cheers. Im changing my engine and plan to run more boost in the next couple of months. What would a sign he that one of these is leaking? Would it be that a certain boost threashold could not be reached? Cheers,dan

Well learn something new every day, my recirc valve is seemingly plumbed in the wrong way according to the diagrams!

Mine too LOL

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

same here....as said seems to work ok.

Standard OEM install....



Compressor outlet (buried low down in photo) is taken off the intercooler inlet and connects to bottom of valve.
Side port is the exit back to the compressor inlet pipe.

It's a simple diaphragm valve, not an exotic twin piston :)

Schrödinger's cat - so which one am I ???

I can see the reason why it is installed as standard that way round, on the cam belt cover

Edited by Sprocket on 15th Jan, 2013.

On 15th Jan, 2013 Sprocket said:
I can see the reason why it is installed as standard that way round, on the cam belt cover

Schrödinger's cat - so which one am I ???

Lets agree to disagree, but before we do, consider this. Under boost, one way acts as a check valve, holds boost better, with boost and spring pressure forcing the valve into its seat, while the other way relies on the spring only to hold the valve shut on its seat............

Edited by Sprocket on 15th Jan, 2013.

Colin,

OK, we'll agree to disagree, but consider this please,

You are absolutey right - in the OEM install, it is intended as a relief valve as well as a dump valve (a bit like the poppet valve in the metro plenum).

So the spring holds boost (apart from excess boost) and the vacuum on the diaphragm then flips it open on throttle close.

So, as you say there may be different spring rates available to achieve this, but my standard "Ford" one (yes, the name on the cambelt cover) holds 1.1bar boost no problem and flips open when plenum pressure drops (throttle closed).

Because these Bosch recurculating valves are a simple single diagphram, there are no different CSAs when they operate (unlike the exotic twin piston types).

So, in standard configuration the normal Bosch one will flip open on 1.1bar(g) boost when it gets a negative pressure on the diaphragm from the plenum when the throttle is suddenly shut.

Negative on the diaphragm is usually 0.2-0.3 bar(a), so minus 0.7-0.8bar(g) on over-run.

That means the normal spring configuration is fine, but if you reverse it, it would require more than 1.1bar NEGATIVE to open it..... even more if the boost is really operating on the back of the plunger when it's installed the wrong way around - I doubt the internals actually allow that - but there is no way vacuum alone can open it in the scenario you describe if it keeps itself shut under 1.1bar boost the correct way around.


The vacuum you would require defies the laws of physics I'm afraid. :)

There is a difference in the CSAs when it's shut (plunger vs diaphragm) but not once it operates as the design is too simple.

So, no, I can't believe it would actually work the wrong way around, especcially under high boost if that really does help keep it closed- vacuum could never win especially as boost spikes as soon as the throttle is closed and this is supposed to open.

Not trying to be provacative, but where do you disagree with my thoughts ???

Schrödinger's cat - so which one am I ???