[Diy_efi] some pictures...

[WSCowell at aol.com]

In a message dated 04/07/2006 18:10:06 GMT Standard Time,  niche at iinet.net.au 
writes:  
Ear cant  discriminate anything useful beyond about 16,000 rpm, at that rate
for a  small turbo it wouldnt develop much boost, what you are likely hearing
is  low order oscillations, resonant cavity either inlet or exhaust but 
certainly  not
anything near turbo spin rate !  Much like the F1 motors, when  they spin at 
19,000rpm,
you dont hear the motors at all, you hear the  gearboxes and the layshafts 
etc etc





Mike, I'm puzzled.  You may be right about the real noise coming from  the 
gearbox etc, although having been close to "only" F3000 engines I don't  believe 
you're correct.  Where I want to query what you say is the maths  about what 
the human ear can hear.
 
A V8 turning at 19000rpm experiences 4 firing pulses every rotation,  
therefore 4*19000/60 pulses every second = about 1300 Hz.  This is well  within the 
human ear's response, wouldn't you agree?  :-)
 
I accept of course that it's not strictly relevant to the turbo rebuild  
theme, being 5 to 10 times slower than a turbo spins at.....
 
Will
Cambridge, UK