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Re: [turbobike] Carb Question

Tue, 23 Nov 1999 07:39:00 -0500

The reason the fuynnybikes wing their engines is that the turbos are huge units
(really almost over-sized for the application and unusable on the street) and
they want boost immediately off the line.  The only way to build boost on the
line is to spin the turbine by increasing the mass airflow past the turbine.
Simply holding the revs up won't do it since the throttle body or carb is almost
closed and flows little air.  So you have to either get wildly on and off full
throttle or go on the 2-step.  A healthy nitrous dump off the line also brings
the boost up.  Once you're up, however, then you're running 40-50 psi boost and
500+ horsepower, depending on your combination.

Your Aerocharger is a very small turbo compared to your friends draw through
(probably an FF40 Rayjay).  His turbo will ultimately make more power, but yours
is more user friendly on a street machine.  The Rayjay is also a very old, high
inertia design which doesn't help.  The normal thing to do on the old Rayjays is
build as much displacement into the engine as possible to make a better match to
the turbo.  My old FJ wouldn't build any appreciable boost until 6000 rpm with
the stock 1098 motor, and then it was like being kicked by a mule.  By bumping
it to 1314cc it built boost at 4000 rpm and only brought peak power down from
10,300 to 10,000 rpm.  It filled in the midrange like you wouldn't believe and
made it much more fun to ride.


ABNZX9@aol.com on 11/23/99 04:28:06 AM

To:   turbobike@natvideo.com
cc:    (bcc: Bob Shammas/EQA/Nsk-Corp)
Fax to:
Subject:  Re: [turbobike] Carb Question

In a message dated 11/22/99 4:21:19 PM US Eastern Standard Time,
shammar@nsk-corp.com writes:

<< I believe that the amount of time it will
 take to fill the plenum will be insignificant.

Could this be why some turbo dragbikes rev the bike repeatedly at the line?
That is one thing I really like about my Aerodyne compared to a friends draw
thru turboed GSXR my bike has no turbo lag whatsover.