> > >>  Sorry to disagree Ken, but on our best drag bikes we use lightened

 > >>crankshafts
 > >>  and clutch baskets. Inertia is inertia, rotational inertia is the
 > >>same. It will
 > >>  take you longer to accellerate the heavy flywheel no matter what
 > >>else happens.
 > >> [snip]
 > >>  Bill Jepson

 An acquaintance of mine who manages an IRL team said something I found
 extremely interesting while showing me some stuff.  I was asking why they
 use lighter suspension components on less demanding tracks since the
 difference in weight is extremely small and the final car weight will be
 exactly the same anyway.  He said they have found that over building
 components tends to lower reliability.

 Keep in mind, I don't speak for him and I'm not a P. Eng.

 Lightened flywheels on two stroke drag outboard engines do help performance
 but only in a barely measurable way.  To go from a stock aluminum flywheel
 to the lightest flywheel that will hold a ring gear will only make about a
 1/10th second difference over a quarter mile.  The flywheels are lightened
 to raise their resonant frequency.  Many stock OMC V6 outboards have a
 resonance at 6200~6400 RPM and they will shear cranks if propped to top out
 at that engine speed unless the flywheel is lightened to raise that
 resonance above WOT engine speed.

 Lightened pistons and rods can help reliability also but I would tend to
 think that roughly anything that reduces vibration, lighter or heavier,
 will be beneficial to reliability.

 My $0.02,

 Tom

    One thing that Atkins said is that there is bad resonant vibration
in the 13b at 6200 rpm and try to stay out of that zone so I try to
run at 6000 or 6500 but in the early days I didn't know that and may
have been beating up the dampers in that zone.
  He also said that the 20b doesn't have that vibration zone.

   Ken

That is nonsense Ken. I have owned six rotary engine powered cars, read all the
engineering information published on the rotary engine for the past 35 years 
and there are no resonant zones in any RPM range up to 11,000 RPM.  One can 
learn how to overhaul a rotary engine and overhaul thousands without 
understanding the physics and kinematics involved in its operation.

Paul Lamar
 
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