[s-cars] RUSS COLLINS on RC ENGINEERING FLOW RATES - Long

[QSHIPQ at aol.com]

Dave:
Thanks for the response.  I suspect that Russ Collins (the 'RC' in 
RCEngineering) factors in more variables based on extensive emperical testing.  Since 
most folks (including me) consider him the Zeus in the mythical world of Fuel 
Injectors, I wanted to translate his own conversions from Mike Pedersons known 
spent dollars on the RS2 injector testing.  Thank goodness I'm just 
regurgitating RC's formulas.  To wit I directly quote RC:

Russ Collins - "Pressure and Flow Changes:  Fuel pressure changes will alter 
flow rates as follows - To find a new Flow Rate from a PSI change, Divide the 
new Pressure (3.8bar) by the rated or old Pressure (3bar).  Find the square 
root of this number and miltiply it by the old or rated flow rate." 

 Dave, I translate that to be:
((3.8/3.0) * sqrt) = 1.125463016 * 360 = New Flow Rate 
New Flow Rate = 405.1cc/min at 3.8bar

To wit 2:
Russ Collins - "To find the Pressure required to produce a Desired Flow Rate. 
 Divide desired flow rate (405.1) by test flow rate (360), square this 
number, and multiply it by the test PSI (3).  The answer is the PSI require to 
produce the desired flow rate."  

Again, I translate that to be:
((405.1/360) ^2) = 1.1268127 * 3 = 3.8bar at 405.1cc/min

I rounded up to 410cc to include test injector variance (MLP got a min of 
360cc).  Dave, however RC arrives at these numbers could be up for debate, but 
they seem to validate each other.  I won't comment on that more than to say when 
a guy like RC uses a formula, I'm sure there's plenty of 'n' attached to that 
(and I sure pay attention!).  Further, he pretty much sets the standards in 
terms of injector baseline.

Russ Collins - "TESTING - RATING at R.C. Engineering we rate all injectors at 
43.5psi/3bar.  The injectors are run for at least 60 seconds in each test.  
This is becoming a universal standard and allows us to accurately compare 
differently rated units.  All currently used injectors are designed to operate 
between 2.5bar/36.25PSI and 3 bar/43.5PSI.  Chrysler sometimes uses 3.7bar/55PSI 
as does Porsche (read:  Audi too).  There are some rare exceptions to these 
standards, but they are rare.  By using 3Bar as standard, we can easily compare 
an injector rated at 252cc at 2.5Bar (36.25PSI), to an injector that is rated 
at 2.7Bar, 3 Bar {,3.8Bar,} or 4 Bar."

I really think the reason RS2's are all over the map is that different 
applications (Porsche vs Audi) may use different system pressures.

For now, we do know that using RC Engineerings Testing of MLP's RS2 
injectors, bringing the RS2 Injector to the standard 3bar rating:
RS2 is a 360cc/34lb injector (not a 32 as some have claimed) 
3.8bar FPR puts it back to 405cc/min using the RS2 FPR system pressure.

Now my question still remains, with a linear rising rate (boosted) FPR, 
what's the upper limit that the FPR can deliver?  Then, what's the working ceiling 
of the injector itself (before "sticking").  Then, does that dictate a better, 
different application?

More fodder for discussion as always.

HTH

Scott Justusson
QSHIPQ Performance Tuning

In a message dated 10/23/2004 12:42:42 AM Central Daylight Time, 
forgied at direct.ca writes:
Scott:  I think you need to check the equation or something.  New Flow
rate over old flow rate (squared) times pressure does NOT equal ANY flow
rate. At least when I taught  engineering. "Watch your units!" - I used
to say.  Your's don't work so your equation is flawed.  I think you
wanted (New pressure over old pressure) (squared) times old flow rate =
new flow rate. (I think).

Dave F.