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Re: [turbobike] Carb Question

Mon, 22 Nov 1999 07:49:13 -0500

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


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
><< 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
> 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,
>eliminate the need for separate pressurization lines for bowl vents, CV
>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,
>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
>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
>'99 M2 Cyclone
>'87 KLR 650 Urban Assault Vehicle
>'78 KZ900 bike in boxes
FZR1000 turbo EFI
(aka The Money Pit)