[Diy_efi] Re: Diy_efi Digest, Vol 4, Issue 18

[Bill Washington]

Sid,
    Care is required because lb/hr is mass/time and cc/min is volume/time.
In any given fluid mass and volume are related by density which changes 
with Temperature and Pressure!

So to relate these two flow rates you need to know the density 
chacteristics of that fluid vs Temp (in degrees Kelvin) and 
Pressure(absolute) - That's a 3D map - admittedly smooth and predictable 
for a known fluid composition - and then add to that the base density 
variabilities and composition variabilities of the fuel which give 
offsets and shape changes to the curve of the 3D surface, not to mention 
differences for different octane ratings and fuel composition 
differences in different countries and different seasons.

Note that fuel injection systems regulate the fuel pressure with 
reference to ambient air pressure, which varies dramatically between sea 
level and a few thousand feet AMSL and then again with the temperature 
of the day.
The temperature of the fuel at the injectors varies with duration of 
engine run, amount of heat soak, fuel usage, rate of recirculation, 
volume of fuel in the tank, ambient temperature of the day, amount of 
cooling the fuel gets in the tank and the fuel lines ...... etc, etc

Suffice it to say that a number of other parameters must be specified to 
compare flow rates expressed in different parameters - this also 
explains the range of conversion factors you have received.
No wonder we need feedback control systems(Lambda sensors)!

All of that being said, the range of figures you have received are 
probably representative in the USA (it would however be worth double 
checking with the Oil companies in Brisbane) then take a middle of the 
range.

Have fun!

Bill W

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>Date: Mon, 7 Apr 2003 12:02:58 +1000 
From: Sid.Young at qml.com.au
>To: diy_efi at diy-efi.org
>Subject: [Diy_efi] converting lb/hr to cc/min
>Message-ID: <F23B3BCF090CCA43A05E70C7B771E5C8122604 at qmlmail.qml.com.au>
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>MIME-Version: 1.0
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>Reply-To: List for general do-it-yourself EFI talk <diy_efi at diy-efi.org>
>Message: 3
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>
>Howdy all,
>
>Does anyone know the conversion factor for lb/hr to cc/min ?
>
>Sid
>
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