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Re: [turbobike] Carb Question

Christer Johansson (christer.johansson@mbox383.swipnet.se)
Tue, 23 Nov 1999 23:39:56 +0100

Im sorry if I was a bit unclear.
What I ment was that on a turbocharged engine ,the plenum wolume
is not that important when under boost, as the turbo will support
the air needs. But when in off boost mode a small plenum will
hurt engine response. The reason I mentioned the draw through systems
is that they use a very small plenum.
Christer

Bryan skrev:

> Christer, I'm not sure about your reference to draw through kits and the
> significance of airbox size.
>
> At 10:38 PM 11/22/99 +0100, Christer Johansson wrote:
> >Yes it is insignificant, just have a look at the draw through kits ,like
> >Mr turbo, almost no plenum and no pipes ,intercooler.
> >But in normally aspirated mode , this is a restriction, hence the
> >priority breather valve. B.t.w Im working on My own version
> >of the priority valve , Im using a 2 stroke reed valve, has anybody
> >tried this before?
> >
> >Christer
> >
> >shammar@nsk-corp.com skrev:
> >
> >> Don't worry: we like counter-discussion.  That's the point of this
> forum.  I do
> >> think that Abraham is onto something.  I believe that the amount of time
> it will
> >> take to fill the plenum will be insignificant.
> >>
> >> Bryan <bgoodwin@iquest.net> on 11/22/99 12:26:04 PM
> >>
> >> To:   Bob Shammas/EQA/Nsk-Corp@Nsk-Corp
> >> cc:   FFDennis@aol.com, turbobike@natvideo.com
> >> Fax to:
> >> Subject:  Re: [turbobike] Carb Question
> >>
> >> Bob, I realilze that boost response and timing is primarily controlled by
> >> the turbine sizing. However, that assuming all else equal. Given a fixed
> >> A/R on the turbine, increasing the size of the plenum volume will increase
> >> the time it takes to fill it. What I'm not sure of is how dramatic an
> >> effect this will have.
> >>
> >> P.S. Not trying to argue, just making friendly counter-discussion. :)
> >>
> >> At 07:49 AM 11/22/99 -0500, shammar@nsk-corp.com wrote:
> >> >
> >> >Realistically you'll never get too much plenum volume.  The need for
> plenum
> >> >volume is all but forgotten on four cylinder engines since the intake
> >> events of
> >> >the cylinders provide an almost uninteruppted flow out of the compressor.
> >> >However, a larger accumulator volume reduces manifold pressure
> fluctuations
> >> >between intake events.  On a twin, you'll run into surge much more
> easily and
> >> >must have a huge plenum.  Having a large plenum is akin to being able to
> >> blow up
> >> >a balloon with full lungs the whole time.  You don't want empty lungs
> >> before the
> >> >intake valve event has finished.
> >> >
> >> >Turbine response (how fast it makes boost) will be governed by the exhaust
> >> event
> >> >and turbocharger matching.
> >> >
> >> >That's just my $0.02.  I've built a few bikes but that doesn't mean
> anything
> >> >either.
> >> >
> >> >Bob
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >Bryan <bgoodwin@iquest.net> on 11/21/99 01:37:26 PM
> >> >
> >> >To:   FFDennis@aol.com, turbobike@natvideo.com
> >> >cc:    (bcc: Bob Shammas/EQA/Nsk-Corp)
> >> >Fax to:
> >> >Subject:  Re: [turbobike] Carb Question
> >> >
> >> >
> >> >
> >> >I think the only problem you would run into there is that the volume of
> the
> >> >airbox would be too large. This might cause the turbo to boost later.
> >> >
> >> >
> >> >
> >> >
> >> >At 10:38 AM 11/21/99 EST, FFDennis@aol.com wrote:
> >> >>In a message dated 11/19/1999 23:56:32 Central Standard Time,
> ABNZX9@aol.com
> >> >>writes:
> >> >>
> >> >><< Now for another question how about intake plenum and attaching it
> to CV
> >> >> carbs?  Should I buy a set of velocity stack and machine them in
> order to
> >> >>fit
> >> >> an intake plenum to the carbs that way?   I have a feeling that the
> intake
> >> >> plenum I am currently using is robbing me of effieciency.
> >> >>  >>
> >> >>
> >> >>You raise another interesting possibility.....If you can encapsulate the
> >> >>entire carburetor within a plenum, and then pressurize the entire plenum,
> >> >you
> >> >>eliminate the need for separate pressurization lines for bowl vents, CV
> >> >slide
> >> >>vents, etc., as you would have equal pressure operating on all sides
> of the
> >> >>crab.  The pressure in the venturi would be lower than the other areas,
> >> >which
> >> >>is how a carb works.  Your next problem is then to seal the throttle
> cables
> >> >>and fuel lines where they pass into the plenum.  I've seen ram air setups
> >> >>like this.  It seems to me that a turbo plenum could get away with being
> >> >less
> >> >>aerodynamic internally due to the mechanical pressurization.
> >> >>
> >> >>Just my .02.........lots of book knowledge and reading, I've never
> built a
> >> >>turbo bike (but I have a KZ 900 motor in pieces, bead blasted, for a
> future
> >> >>project......)
> >> >>
> >> >>Dennis
> >> >>'99 M2 Cyclone
> >> >>'87 KLR 650 Urban Assault Vehicle
> >> >>'78 KZ900 bike in boxes
> >> >>
> >> >>
> >> >bgoodwin@iquest.net
> >> >FZR1000 turbo EFI
> >> >(aka The Money Pit)
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> bgoodwin@iquest.net
> >> FZR1000 turbo EFI
> >> (aka The Money Pit)
> >
> >
> >
> >
> >
> bgoodwin@iquest.net
> FZR1000 turbo EFI
> (aka The Money Pit)