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[Land-speed] Multiple Engines

To: "land-speed" <land-speed@autox.team.net>
Subject: [Land-speed] Multiple Engines
From: "Kirkwood" <saltfever@comcast.net>
Date: Wed, 24 Mar 2010 18:16:49 -0700
It seems to me you may be smoothing out your torsional frequency. As Dave
mentioned the cylinder pressure is greatest somewhere around 14 degrees. If
you index the motors 45 degrees the pressure peak (on the rear motor) will
occur every 22 degrees. In addition the rear crank is preloaded with the
torque input of the front engine. That means the rear crank never returns to
its single engine torque value. You have decreased the amplitude of the
torque input and doubled its frequency.  For example, let's say one firing
impulse results in a pressure of 1,000 psi and bleeds down to something like
500 lbs due to overlap from the next firing cylinder. With the front engine
introducing a torque peak 22 degrees later the crank never returns to its
lowest state of a single motor. Torque amplitude is less and frequency
doubles. The only issue I see is doubling frequency moves anything closer to
destructive harmonics, but is it germane here? I think John Burk might be
right.
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