Fuel pressure / Flow rate formula

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In a message dated 11/12/98 3:23:44 PM Pacific Standard Time,
houlster at user1.inficad.com writes:

<< Subj:	 Fuel pressure / Flow rate formula
 Date:	11/12/98 3:23:44 PM Pacific Standard Time
 From:	houlster at user1.inficad.com (Daniel Houlton)
 Sender:	owner-diy_efi at efi332.eng.ohio-state.edu
 Reply-to:	diy_efi at efi332.eng.ohio-state.edu
 To:	diy_efi at efi332.eng.ohio-state.edu
 
 What's the formula for figuring out the flow rate of an injector if you
 bump up the fuel pressure?  I've found 2 different ones that give *huge*
 differences in the result.
 
 The first is from an MSD fuel management catalog/brochure I have.  It
 states that 
 
 
 F2 = sqrt(P2 / P1) * F1
 
 
 For me, I have a 20 lb injector at 40 psi and I want to check the flow
 at a maximum of 70 psi, so
 
 F2 = sqrt(70 / 40) * 20  =  26.4 lbs/hr
 
 
 Not as much as I had hoped.
 
 I then found a different formula on the RC engineering page 
 http://www.rceng.com/technical.htm.  It's almost the same, except that it
 uses a strait ratio between the pressures instead the square root of them,
 so according to them, I have:
 
 
 F2 = (70 / 40) * 20  =  35 lbs/hr
 
 
 
 This is a very large difference.  Which one is right?
 
 
 thanks
 --Dan
  >>
The square root one is correct for a pretty close guesstimate.....The RC guys
must have forgotten that part of the equation when they put it on the
net....but I feel they do know which is right.....hth's
-Carl Summers