[s-cars] By-pass valves
djdawson2 at aol.com
djdawson2 at aol.com
Thu Aug 12 10:51:38 PDT 2010
I heard he can get a golf ball through a garden hose....
jk, of course...
-----Original Message-----
From: Hap Maguire <captmagu at gmail.com>
To: DGraber460 at aol.com
Cc: qshipq at aol.com; djdawson2 at aol.com; benswann at verizon.net; esanborn at gmail.com; quattro at audifans.com; s-car-list at audifans.com
Sent: Thu, Aug 12, 2010 10:23 am
Subject: Re: [s-cars] By-pass valves
Hey Dennis
I've seen Dave Jones test a bypass valve by sucking on it. He is called Tufty
for a very good reason.
Hap, wit dakine Tuftyism not from Evahboost, Maguire
On Aug 12, 2010, at 4:10 AM, DGraber460 at aol.com wrote:
>
> Thanks Scott, Dave, et al;
> I understand the Bosch Audi OEM's operation pretty well as described by Dave
and Scott.
> Having said that, my question was, and is, should the OEM plastic valves open
on the bench with vacuum applied to the small control port? The Forge aluminum
valve does, but neither of my OEM plastic units will, and I hear what seems to
be air bleeding by the diaphragm when vacuum is applied.
> They have never (at least in my ownership) been installed backwards, but
wondering if they need to replaced and tossed, or if they are as normal for a
stock OEM. I'm guessing from this behavior that the diaphragm is ruptured and
they are toast?
> TIA
>
> Dennis
> Denver
>
>
>
> -----Original Message-----
> From: qshipq at aol.com
> To: djdawson2 at aol.com; benswann at verizon.net; esanborn at gmail.com;
dgraber460 at aol.com
> Cc: s-car-list at audifans.com; quattro at audifans.com
> Sent: Thu, Aug 12, 2010 7:36 am
> Subject: Re: [s-cars] By-pass valves
>
>
>
>
> Agree, many are mixing bypass valve operation with blow off valve. I have not
seen any bypass valve that boost helps 'blow open' from below. Most (all audi
apps) are oriented as DJD explains with the boost 90degrees to the diaphram.
The HKS sequensial bypass valve is oriented with the diaphram in line with the
boost pressure. However, it's operation is spring adjusted and operates as a
stepped 'needle valve', so it's still the feed line on the device that dictates
valve opening and close.
>
> A blow off valve oriented with the diaphram in line with boost pressure, has
no intake feed, it is an absolute boost pressure device that pops when the boost
in the intake manifold exceeds a set pressure.
>
> Scott J
>
>
> -----Original Message-----
> From: djdawson2 at aol.com
> To: benswann at verizon.net; esanborn at gmail.com; dgraber460 at aol.com
> Cc: s-car-list at audifans.com; quattro at audifans.com
> Sent: Wed, Aug 11, 2010 11:20 pm
> Subject: Re: [s-cars] By-pass valves
>
>
>
>
> Mixing terms... and what you're saying isn't really accurate.
>
>
> The valve, is normally closed. Apply a vacuum and it opens. Apply boost and
it
>
> remains closed. The signal comes from the intake manifold. The intake
manifold
>
> in a naturally aspirated engine is always in some state of vacuum. This means
>
> that if you are not making any boost, there will be a vacuum in the intake...
>
> inclining the BPV towards opening.
>
>
> Positive manifold pressure will NOT "assist to force or blow the valve open
>
> when vacuum is applied to the control port" because those 2 things can't ever
>
> happen at the same time. If there is pressure in the intake, there is
pressure
>
> forcing the BPV to remain closed. When there is vacuum in the intake, there
is
>
> vacuum at the BPV opening it up. Furthermore, boost hits the *side* of the
>
> piston (Forge) or diaphragm (Bosch)... never able to assist in opening the
>
> valve, unless you have it improperly installed.
>
>
> If as stock BPV is installed backwards, you will blow the diaphragm in short
>
> order... it's just rubber, and it won't last long fighting 20+ psi.
>
>
> The BPV's purpose is to alleviate pressure stall in the intake plumbing (and
>
> therefore the turbo) when the throttle closes.
>
>
> Anyway....
>
>
>
>
>
>
>
>
> -----Original Message-----
>
> From: Ben Swann <benswann at verizon.net>
>
> To: esanborn at gmail.com; dgraber460 at aol.com
>
> Cc: 'Quattro List' <quattro at audifans.com>; s-car-list at audifans.com
>
> Sent: Wed, Aug 11, 2010 6:51 pm
>
> Subject: Re: [s-cars] By-pass valves
>
>
>
> No, just the opposite. The Bypass valve is normally closed. The control port
>
>
> is vacuum
>
>
> actuated and tends to open the valve. Positive manifold pressure will assist
to
>
>
>
> force
>
>
> or blow the valve open when vacuum is applied to the control port. This
happens
>
>
>
> only
>
>
> when the throttle valve snaps shut while engine is under positive pressure -
>
>
> like
>
>
> between shifts.
>
>
>
>
> So the mityvac test is not necessarily going to tell you if the valve is
opening
>
>
> properly and some valves have beefier springs for higher boost pressure.
>
>
>
>
> Also, if the valve is installed backwards then it may not open or flutter when
>
>
> opening,
>
>
> or open when it should not open. Funny thing is the way most valve are
>
>
> oriented, the
>
>
> correct way does not look correct. You might want to verify that the
direction
>
>
>
> of the
>
>
> valve is correct.
>
>
>
>
> See: http://www.gtquattro.com/Bypass-Valve.html that has a picture of how the
>
>
> valve is
>
>
> connected/oriented.
>
>
>
>
> Ben
>
>
>
>
> [Date: Wed, 11 Aug 2010 17:56:43 -0400
>
>
> From: Eric Sanborn <esanborn at gmail.com>
>
>
> Subject: Re: By-pass valves
>
>
> To: dgraber460 at aol.com
>
>
> Cc: s-car-list at audifans.com, quattro at audifans.com
>
>
> Message-ID:
>
>
> <AANLkTin-vkgjJaotOtbbX3ToE1Ab-yLvLzkJ2293n-xq at mail.gmail.com>
>
>
> Content-Type: text/plain; charset=ISO-8859-1
>
>
>
>
> I might be misunderstanding what you were testing, but they should only open
>
>
> during boost.
>
>
>
>
> On Aug 11, 2010 5:12 PM, <dgraber460 at aol.com> wrote:
>
>
>
>
> List-et-al;
>
>
> I have been chasing a full throttle issue on my 3B'd URQ for a few months
>
>
> now. The symptoms have been a flattening and lack of power under full
>
>
> throttle. My boost gauge has always shown full boost at 19-20, and it throws
>
>
> no codes. I started to notice the moaning (not whooshing) noise when off
>
>
> throttle, which I had heard before and found to be an aluminum bypass valve
>
>
> that needed cleaning.
>
>
> Since it had been running an OEM Bosch plastic valve, I pulled the Forge
>
>
> valve off the S-Car and cleaned it up and installed it. On the drive this AM
>
>
> it seems to have cured the issue. Time will tell if total cure.
>
>
> The question I have is that I tried to test all 3 valves that I have while
>
>
> messing around last night. I have 2 plastic, and 1 Forge valve. I hooked up
>
>
> a vacuum pump that pulls 14 lb hg to each valve individually and _none_ of
>
>
> them would pull open. Then I used my little Mighty Vac hand pump and the
>
>
> Forge valve would pull open and stay. Neither plastic OEM valve would open
>
>
> with either test. Does this indicate both OEMs are toast?
>
>
> I assume the vacuum pump did not have a check valve and therefore could not
>
>
> "build" vacuum as the Mighty Vac did, thus letting the valves flutter but
>
>
> not pull open. Sound reasoning?
>
>
> Also - is there a recommended lubricant that keeps the aluminum valves
>
>
> happy, and functional, or should they remain dry?
>
>
>
>
> Dennis
>
>
> Denver
>
>
> ]
>
>
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