entropy
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posted March 22, 2009 01:02 AM
quote:
interesting.. more and more crazy stuff i learn every day.
i would think (personally here.. just my possibly wrong 2 cents) that the pulsation is caused from a "harmonic" reached due to the frequency of the injectors opening.. it's called pressure piling.. once the pressure reaches a dead end it's going to either be absorbed or reflected, thus causing waves or pulses.. certain freqs will generate multiples of that root freq and it'll get progressively more intense.. (within reason) even tho (assuming) its a friction pump, there are minute pulses generated strictly due to the nature of how the gas is pressurized and pumped.. i think a centifugal pump is about the only type of pu,p that won't prduce any pulses at all.. gear and friction pumps are in insanely close second tho.
the whole effect can be thought of as water hammer when you shut the faucet off quickly.. flow and pressure are up and going then all of a sudden.. no taper down to stop.. it's just STOP. do that at the right intervals and you can probably shake the pipes apart in your house and piss your neighbors off trying to take a shower.
your thoughts?
very interesting tho.. +1 for the easy fix !!!!
how badly did you hurt the 14??
i work with a buncha mech engineers, they also talk about acoustic resonsance.
what is causing it? who knows? It is not normal, oh well at least i have a fix.
bike is gonna sit till the Mile!!! 
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Y2KZX12R
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posted March 22, 2009 10:50 AM
 Edited By: Y2KZX12R on 22 Mar 2009 18:54
quote:
i would think (personally here.. just my possibly wrong 2 cents) that the pulsation is caused from a "harmonic" reached due to the frequency of the injectors opening.. it's called pressure piling.. once the pressure reaches a dead end it's going to either be absorbed or reflected, thus causing waves or pulses.. certain freqs will generate multiples of that root freq and it'll get progressively more intense.. (within reason) even tho (assuming) its a friction pump, there are minute pulses generated strictly due to the nature of how the gas is pressurized and pumped.. i think a centifugal pump is about the only type of pu,p that won't prduce any pulses at all.. gear and friction pumps are in insanely close second tho.
the whole effect can be thought of as water hammer when you shut the faucet off quickly.. flow and pressure are up and going then all of a sudden.. no taper down to stop.. it's just STOP. do that at the right intervals and you can probably shake the pipes apart in your house and piss your neighbors off trying to take a shower.
your thoughts?
I think your right .....
Ive seen fuel rail pulsation problems before, where, at a certain injector frequency (RPM) the needle goes bazerk and then settles down again to a "normal" needle bounce right after it sweeps past that frequency.
It must either absorb it or change the resonant frequency at which the systems fuel mass (water hammer) goes bazerk. ????
But yea, the root of the problem is the injectors opening and closing.
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entropy
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posted March 23, 2009 03:59 AM
re-did the plumbing for the damper this weekend.
When hung directly on the r end of the rail, it interfered with my R knee a bit (in a tuck), so with a lil,bit of jiggery-pokery and some brass NPT fittings it is out of the way,
Ready for the Mile!
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KZScott
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posted March 23, 2009 04:12 AM
kinda related question. how would putting a "Y" fitting in the fuel line and feeding the fuel rail from both sides affect pulsation? any? (leaving the return line as is.)
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entropy
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posted March 23, 2009 07:15 AM
quote:
kinda related question. how would putting a "Y" fitting in the fuel line and feeding the fuel rail from both sides affect pulsation? any? (leaving the return line as is.)
no idea????
i don't even know if the pulsation affected hp??
I just didn't like seeing it on the gauge.
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WRECKSHOP
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posted March 23, 2009 07:51 AM
Show us an install picture, if you will ?
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entropy
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posted March 23, 2009 09:06 AM
quote:
Show us an install picture, if you will ?
I'll take sa pic at the Mile; it looks pretty cool .
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Y2KZX12R
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posted March 24, 2009 06:39 PM
I wonder if we would need a damper if we ran these bikes on a bose condensate made from carbon?
Could there be a pulsation? 
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whitehendrix
Zone Head
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posted March 24, 2009 06:54 PM
hmm.. scott.. you might kinda be onto something there buddy! there wouldn't be a reverberation of the back pulses off the plugged end of the rail back towards the inlet that way.. if theory in my mind pans out, i'd say theres a possibility it would effectively cancel out at least 50% or better the amount of noticed pulses.
now, i'm no mech engineer, but i learned a bit while working with them as an EE at various plants and all.. i've found alot of electrical formulas and other bits of info translate nicely.
such as wavelengths and whatnot.. not, considering ther e would be a wavelength generated during that pulsing crap, i'd say for sure you could tune a dead-end pipe or the rail itself to attenuate that freq if the offending freq is noted, and maybe the first few harmonics. i used to do alot of RF work at wavelength and freq are related thru the formula (i think for a full wavelength.. can't recall now..  ) L (lamba)= 468/F(mhz)
been years since i've done any RF stuff tho.. i'm guessing it'd cross over given you can note the actual freq.
anyway.. at least there IS a simple solution to all this instead of lots of engineering and number crunching!!!!! that little accumulator is a great idea. good luck Karl!!!
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entropy
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posted March 24, 2009 11:38 PM
quote:
Show us an install picture, if you will ?
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WRECKSHOP
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posted March 25, 2009 07:34 AM
Okay, great....looks good and seems to be a fairly easy install by the pics....Thanks for sharing !!!
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entropy
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posted March 25, 2009 08:00 AM
quote:
Okay, great....looks good and seems to be a fairly easy install by the pics....Thanks for sharing !!!
Easy is a relative term...
I had to take the TB's off 4 times to get it right, 3 times to get the fittings correct and once cause a joint leaked.
My TB's are a lil bit of a PITA to R&R bc i have aftermarket (taller) injectors.
If i ever do it again i will use aircraft compression fittings. They look cooler and don't leak.
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psycho1122
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posted March 25, 2009 08:14 AM
Nice work Entropy!
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entropy
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posted March 25, 2009 09:00 AM
quote:
Nice work Entropy!
thanks, Dr Psycho!!
I really don't expect any earth shattering gains, but pretty cool looking device, eh?
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TRNorBRN6001
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posted March 25, 2009 01:51 PM
I wish I had a flux capacitor like that!
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