airbox twiddling etc

[yamaha_george]

hi,
Ok on a tech list the following came across:-
QUOTE:-

A simple method is:
engine size + 15%.
This is fine for engines under the 5252rpm area.  Thus its fine for cars
and what not.  It basically compensates for the vacuum that the manifold
is under.

double it for every factor of 5252rpm.  So a 10,000rpm engine would be
2x (engine + 15%), and 20,000rpm would be 8x..
Ram-air can help even further by keeping the approx ratio, BUT reducing
the physical size because its got good efficiency.

Airbox shape also has an impact.  As does filter and outlet placement..  
IE: where it attaches to the throttle body.

UNQUOTE.

Feel free to go look at your own bikes airbox & discuss freely...............................

[yamaha_george]

For those of you who wondered where the "magic number " 5252 came from :-
Bigger is simply better for power production and the figure of 5252 has nothing
to do with it.   That number is simply where the torque and power curves cross
and is merely a function of the definition of the units of physics defined
hundreds of years ago.   In particular, James Watt determined that a Scottish
draft horse could produce 33,000 foot pounds of work per minute.   Since the  
"distance"   traversed by a rotating shaft can be rationalized as that of a rope
pulling on a drum or pulley, the distance excursion of that rope is  Pi  times  
the pulley diameter or  2 x Pi x the pulley radius or


2 x Pi x r

Since torque is measured at a radius and power is work per unit of time, the
power (P) = (torque (T) x 2 x Pi ) / time

P = T x 2 x 3.14159

and P/ 6.283 = T

where 33,000 / 6.283 = 5252

[chefen2006]

You gave me a headeache there G....

[yamaha_george]

You gave me a headeache there G....

Chefen,
Wait till your my age you get the headache from the thinking & math and hang over from the amber coloured brain lube eg JD, SC etc

[trifgeorge]

very usefulll info, because i was going to get miself some trouble trying to do a crazy mod to my air intake to fit the yzf 600 tank

[thatkid]

very usefulll info, because i was going to get miself some trouble trying to do a crazy mod to my air intake to fit the yzf 600 tank

Been there done it.

My baby holds up, to both requirements, airflow and stability. My girl pulls like a train NO performance issues whatsoever. I have ensured that, the airbox is intact after around 400 miles of testing. viewtopic.php?f=30&t=6284