Subject: Motor mounts integrated with redrive plate
From: Paul
Date: 10/19/2000, 8:27 PM



Here is the front view showing why it is a good idea to move
 the motor mounts outboard  to clear the turbo and muffler if used.
 Also you can see why a bottom mounted starter would get in the
 way of the rad. This rad may look a bit over kill compared
 to Chuck Dunlap's 533 cubic inch rad  but I want to be real
 sure I can cool the turbo motor at what ever boost results
 in acceptable rotor housing temp and turbine inlet temp.
 Those are the two limits we must stay within in any engine.

 BTW Bill this is the short cowl version of the Kis Cruiser.
 I used the short cowl because the turbo motor is heavier than
 the NA motor by about 35 pounds.

 Paul Lamar



Using the mock up is very useful.  I am planning normally aspirated, but
using the radiator under the engine also.  Have a redrive from Tracy on
order.  Am very interested in the side mount starter position.

Bill Schertz
Kis Cruiser #45


A subtle advantage to the motor mounts integrated with redrive plate
is Tracy spacer blocks and ten mm bolts do not have to deal
with prop torque. Since the peak torque in a rotary is roughly
twice the average torque you get two 400 ft pound torque pulses twice
per rev. When you feed this through the 2:1 gear box (mitigated some what by
Tracy's damper plate) you get four 800 ft pound torque pulses per prop
rev on the prop. These are normally fed back through the spacers blocks 
and the ten mm bolts and into the motor mounts. With the  motor mounts 
integrated with the redrive plate they go directly into the motor mounts.

Spacing the motor mounts two feet apart rather than only one foot halves 
the blow from these torque pulses. The motor mounts are subjected to a steady
150 pounds apiece  due to the static weight of the engine.
The torque pulses are on top of that. One mount is seeing  an increase 
and the other a decrease. At 12 inches apart one is seeing 150 pounds 
plus 400 pounds or 550 pounds and the other is seeing  150 pound minus 
400 pounds or -250 pounds. 

At 24 inches apart one is seeing 150 pounds plus 200 pounds
or 350 pounds and the other is seeing  150 pound minus 200 pounds or
-50 pounds. Halve these number for the average prop torque.

I think this wide motor mount spacing will help the vibration 
isolation enormously.

Paul Lamar

 
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