I have been working on making an excel sheet to calculate injector flow rates, to get an adequate size design for a surge tank.
I found this guys thread…
http://forums.nasioc.com/forums/showpost.php?p=21443184&postcount=20
and if you pump his numbers into the calculator RC Fuel injectors site (with the formulas which I used in my excel sheet) they dont match. The part about adding 10Psi to his 270cc injectors to be exact.
he says they are now “332.79cc’s”, yet RC’s site & math say its only 299.76CC.
Infact to hit his flow rate assumption it needs 22psi more pressure as per RC’s site.
Now he is taking the flow at base pressure and finding how many CC’s it flows at 1psi. Taking that number and multiplying it by the pressure increase to get the “additional flow” from that pressure increase. OR
270CC @ 43psi = 6.279CC per 1psi
then 6.279CC * 10 = 62.79CC more flow from the injector or 332.79CC total
BUT as per RC Injectors math its nowhere near that. (I assume it takes in account it cant be a static 1:1 ratio) http://www.rceng.com/technical.aspx
50/43=1.162, then the square root of 1.162 = 1.110, then that X the old flow rate (270) or the new injector flow rate of 299.76CC total.
Based on RC’s figures:
299.76cc / 50 psi = 5.995 CC per PSI
270cc / 43 psi = 6.279 CC per PSI
/\ not a 1:1 ratio PSI:CC like that first guy assumed.
So who is right? :pop
I assume since the orifice at the end of the injector doesn’t change, it throws off the theory.