There are very long equations for the 1st, 2nd and 3rd harmonics
that govern the design compromises made to reduce dynamic
vibration.
Your TR6 is pumping out 250 power strokes per second at redline
and 50 per second at idle - a little more of a blur compared to
the water wheel.
Mike L.
60A,67E,59Bug
----- Original Message -----
From: Kai M. Radicke <kmr@pil.net>
To: MG List <mgs@autox.team.net>; Triumph List
<triumphs@autox.team.net>
Sent: February 6, 2001 9:39 AM
Subject: Engine Design Theory: Mutli-Plane Cranks
> Let me initially say that I am nearly ignorant of modern
engines. That
> said...
>
> As I was trying to fall asleep last night, I began to wonder why
the crank
> for my inline six (TR6) motor has all of the journals in the
same plane (I
> suppose you could argue that there are two planes though).
Would it not be
> more efficient (for multiple reasons, getting at them later) to
create a
> crank shaft with journals say within three difference planes,
all separated
> by 120 degrees?
>
> Reasoning? Well last night I likened it to a water wheel.
Obviously, a
> water wheel with two "splash boards" is not going to be as
efficient or as
> powerful as one with more than two splash boards... until of
course you hit
> upon decreasing returns, but that is once you add lots of splash
boards.
> Anyway, for the purposes of relating this to a crank... a water
wheel with
> two splash boards will have a high rate of deceleration, and
will be less
> balanced than a water wheel with three or more splash boards,
both of which
> mean lost energy which we feel as less power.
>
> Obviously the most notable change to the design of the motor,
other than the
> crankshaft, would be how you go about the timing. But I can't
imagine that
> to be too difficult.
>
> Is there some reason why multi-plane cranks are not more popular
(again,
> like I said I know nothing about modern day motors)... ?
Obviously, I am
> not talking about motors with V blocks either.
>
> Thanks,
>
> Kai
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