I've been studying this question. How much does weight reduction buy in
top speed?
Basic physics tells us that, all else being equal, and there being an
infinite amount of space to accelerate in, weight has no bearing at all on
top speed. Rolling resistance, coefficient of drag, and the mechanical
limits of the engine are the controlling factors.
But the real world seldom precisely matches up with textbook theory. For
starters, additional weight results in additional rolling resistance.
Additional weight also places an extra burden on the engine as it
accelerates, and -- since we do not in fact have an infinite space to
accelerate in -- power lost early in the acceleration to overcoming
inertia cannot be made up later, unless the engine reaches its mechanical
limits on the run (and if that happens, then we have hit an immovable
brick wall, so we must assume that the mechanical limits will not be
reached).
I am having a hard time finding useful data, but what I have found so far
suggests a relationship of approximately 1 mph for every 12 lbs, at the
speeds I hope to be going (this relationship would necessarily change at
other speeds, depending on the amount of effect the coefficient of drag is
having on the motorcycle -- quite high at Bonneville speeds, but
inconsequential at legal speeds).
Taking a look at the drag racing world gives some indication: their
environment includes a *very* limited space to accelerate (only 1/4 mile*
instead of the three miles I'll have) so power lost to overcoming inertia
has a dramatic effect on their trap speeds. Playing with one calculator
intended for drag racers suggests they see about .75 mph gain for each 12
lbs lost, close to my rough estimate from magazine tests. *If* it is
possible to still be accelerating at the end of three miles then this gap
should still exist in some form at the traps. If, however, the engine is
no longer able to overcome wind resistance or has reached its mechanical
limits, then this effect would be nullified.
It would be an interesting study to strap 12 lbs of ballast onto the ZZR
for a run and see if there is a measureable change. Could I be consistent
enough to note a 1 mph change? Maybe, maybe not. I used to be able to drag
race consistently enough to tell an improvement in performance from
switching air intake systems on the Firebird, but then again, I used to do
an awful lot of drag racing.
I guess it depends how well I take to thissalt stuff.
All of this boils down to a basic question: will, or will not, the
ZZR-1200 still be accelerating at the end of the third mile? If it is
*not* still accelerating, then no adjustment to weight will improve its
time. If it *is* still accelerating, by whatever small amount, then it
will be possible to capture higher trap speeds by reducing the amount of
power lost to overcoming inertia.
As there is absolutely no safe way for me to test this hypothesis here in
West Virginia, I choose to assume that I will still be accelerating at the
three-mile mark. Therefore, if I can find ways to trim weight off the
bike, I will. I am not sure what the rules will let me get away with --
not much, I should think -- so I will start by trying to trim some more
weight off its rider.
PS. This exercise also suggests to me the importance of pinning it right
out of the gate, and to not get lazy just because there's so far to go.
Pin it and hold on, boys!
* interesting note: the ZZR's trap speed in the quarter mile is 135 mph.
Think about that. I will be at 135 in the first 1/12th of the course.