Pressure in at the bottom and vented to the right or the other way around so the vacuum does all the work..
which way is it fitted...?
Pressure in at the bottom and vented to the right or the other way around so the vacuum does all the work..
Normally bottom goes to boost on all AFAIK.
quote:
Originally posted by coyoteboy
Normally bottom goes to boost on all AFAIK.
As i first thought then i started thinking! Hehe.. Doh!
Thanks
I'm going to have to disagree until I realise I'm wrong (wont take long!), bosst goes in the side and vents out the bottom, I first thought it'd be the other way round but then boost pushes it open all the time, you only want the vac hose at the top to do the actuating.
quote:
Originally posted by flibble
I'm going to have to disagree until I realise I'm wrong (wont take long!), bosst goes in the side and vents out the bottom, I first thought it'd be the other way round but then boost pushes it open all the time, you only want the vac hose at the top to do the actuating.
quote:
Originally posted by flibble
I'm going to have to disagree until I realise I'm wrong (wont take long!), bosst goes in the side and vents out the bottom, I first thought it'd be the other way round but then boost pushes it open all the time, you only want the vac hose at the top to do the actuating.
I'm going to have to go see tommorow what happens if I turn it round on the SAAB, it's been on the other way all year 
quote:
Originally posted by flibble
I'm going to have to go see tommorow what happens if I turn it round on the SAAB, it's been on the other way all year
Id be interested to see the result actually. Been looking around on T'interweb and now I'm back to thinking I may be right, at least for the standard bosch recirc that SAAB's come
with.. >Like this< I'll try it the other way out of curiosity though
I seem to remember it was with a supercharger on my MX6 that it would't work properly with the boost to the bottom either, but then, I'm
wrong about a lot of things!
[Edited on 1-11-11 by flibble]
With boost in the bottom it would guard against a backfire through inlet..??
TBH I may just vent the outlet (which ever it is) to air for now as there aint much room for extra pipe work and sending hot air back to the charger
doesnt make much sense. . . .
Which is it!? 
Edit- inlet must be the bottom... cause why do they have different rate springs?? vacuum will be the same when butterflies are closed...? but more
boost requires a stiffer spring..
[Edited on 1/11/11 by Craigorypeck]
This is mine, its not a recirc so that could be where were disagreeing.
Dump Valve in
I've stripped an atmos-venting one apart to modify it, the bottom is the boost connection. It has a small plunger diameter that seals into the bottom hose. In the case of a supercharger that builds boost at idle it's a bit different, but in a turbo engine there's only boost with the throttle open. The piston is biased via a spring so it's held shut and the small diameter plug presents force X to the piston. When the throttle is opened the boost is present at the top AND the bottom and the top has a larger surface area, presenting 3-4x the force on the piston (or diaphragm) - this holds it shut during boost and only actuates when the throttle is shut providing positive pressure to the small plunger and "negative" to the larger side, holding it open. Providing boost to the side inlet won't do a lot, other than leak a bit during boost. It'll still blow off but it'll leak too,
that makes sense.. thanks!
every aftermarket dump valve ive seen (both dump to atm. and recirc) have been boost into the underside, and then recirc type dump out the side.
The Bosch type black plastic recirculate has flow direction printed on it, in at the bottom, out the side iirc.
Interestingly though they are installed backwards on vag 1.8t engines as standard, I found this on my octavia vrs and s3. They were plumbed in the
side, out the bottom.
[Edited on 1/11/11 by Stott]
Boost in the bottom so it acts against the spring, this is then preloaded so becomes very sensitive to vacumn and provides an overboost protection so set the spring preload with shims a few PSI above maximum allowed boost so it will vent if all goes wrong or if for example the vacumn pipe becomes disconnected or splits.
quote:
Originally posted by mark chandler
Boost in the bottom so it acts against the spring, this is then preloaded so becomes very sensitive to vacumn and provides an overboost protection so set the spring preload with shims a few PSI above maximum allowed boost so it will vent if all goes wrong or if for example the vacumn pipe becomes disconnected or splits.
quote:
Originally posted by mark chandler
Boost in the bottom so it acts against the spring, this is then preloaded so becomes very sensitive to vacumn and provides an overboost protection so set the spring preload with shims a few PSI above maximum allowed boost so it will vent if all goes wrong or if for example the vacumn pipe becomes disconnected or splits.