This is taken from the RC Engineering's website.

http://www.rceng.com/technical.htm

In short, to skip all the mumbo-jumbo. I'm trying to find out what the system fuel pressure @ fuel rail is in PSIG. Below explains why I'm questioning it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Actual Desired Crankshaft Horsepower 300 B.H.P.
Number of (same size) injectors to be used 4
Brake Specific Fuel Consumption desired .63
* See note below.
Maximum Injector Duty Cycle you will see .80
Warning: Duty cycle should not exceed 80% for these calculations.
System fuel pressure @ fuel rail 58.2 PSIG (43.5psi + 14.7a)
(Static flow) injector required @ test PSI of 43.5 51.15 Lb/Hr 538 cc/min

* Brake specific should be .45 to .50 for naturally aspirated engines,
.55 TO .60 for supercharged engines,
and .60 to .65 for turbocharged engines. </TD></TR></TABLE>

My question lies in the "system fuel pressure @ fuel rail in PSIG" Is PSIG actually just PSI or is it, PSI + 14.7 (atmospheric)? RC's default entry is 175PSIG. I know that's not correct. But If you compute the supplied numbers with 175PSIG it gives me 309cc/min (that doesn't seem right), with the "system fuel pressure @ fuel rail @ 43.5PSIG" it comes out to 624cc/min(thats a little more believable - but still doesn't seem right) and at 58.2PSIG (43.5psi + 14.7a) it comes out to 538cc/min (which seems correct).

Please guide me in the right direction. Thanks.

 

psig: Pounds per square inch, gauge. Pressure indicated by a pressure gauge.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MajorPayne &raquo;</TD></TR><TR><TD CLASS="quote">psig: Pounds per square inch, gauge. Pressure indicated by a pressure gauge.</TD></TR></TABLE>

Right, to get psig you must add 14.7 (atmospheric pressure) to the psi number.

psi =/ psig