Fuel pressure / Flow rate formula

[Duc]

On the same note where can I find info on choosing the correct injector for
a specific app. without trial and error.

Derek


David A. Cooley wrote:

> The problem lies not in pumping the pressure up, but the rated max
> operating pressure of the injector...
> You crank up the FP too far past the rated pressure (in your case 40psi)
> and 1 of 2 things happen... the injector gets held open by the fuel
> pressure, or it refuses to open because of the excessive pressure.
> The safest and most reliable route is find an injector that flows what you
> need in it's rated capacity.  Overpressure kills them.
>
> At 04:17 PM 11/12/98 -0700, you wrote:
> >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
> >
> ===========================================================
>            David Cooley N5XMT           Internet: N5XMT at bellsouth.net
>      Packet: N5XMT at KQ4LO.#INT.NC.USA.NA   T.A.P.R. Member #7068
>        I am Pentium of Borg...division is futile...you will be approximated.
> ===========================================================