Fuel pressure / Flow rate formula
Daniel Houlton
houlster at user1.inficad.com
Thu Nov 12 23:17:18 GMT 1998
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
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