Good morning. This is semi tech article #3 in regards to our
Nissan Fuel Delivery system. Here are my previous articles.
These should be considered prerequisites before reading
today’s article.TZR; Fuel Injector Analysis, Physical Properties of.
TZR; Stock 1990 Fuel Rail Analysis, Passanger Side. Disclaimer;
First, I want to start of by touching on fuel itself. All
the analysis I will show today, will be based on a fuel rail
at 45pounds of fuel pressure. In real life applications
fuel pressure is dynamic and varies based on fuel delivery
rate. In general, the more fuel you deliver, the less
pressure in the rail. As fuel pressure drops, fuel velocity
rises. In future tech articles, I will show how each fuel
rail functions in worst case conditions of low pressure /
high velocity. This is where the design of a fuel rail
becomes critical. The intent of this article is to show what the border fuel
rail looks like from the inside out. This thread will be
fairly brief, and questions and comments are always welcomed. This is the Border Fuel rail as commonly sold as a
performance fuel rail; 
So let’s start off with what I consider as one of two
massive downfalls of this fuel rail. Notice the orientation
of the fuel injectors inlet, versus the fuel rails main
plenum. It's significantly not on plane with the main
plenum. This will become evident as a problem in our
analysis that follows. 
The other issue, that is not shown, is the fact that this
fuel rail is not thermally isolated from the lower plenum.
What does this mean? It means that the metal to metal
contact between the lower plenum that we mount to, and the
fuel rail, allows the fuel rail to accept heat into the fuel
rail and will transfer heat to the fuel. 
In this view, I want you to take notice of the AN6 Male to
Male fitting. The AN designation stands for
"Airforce-Navy" and is a high tolerance military
specification. (AN815 Union,Flared Tube.pdf).
In this specification, you will notice that it refers to
meeting the requirements of MS33656 ("MS33656 Fitting End,
Flared Tube Connection"). This document is very specific
such that the seal that is created by metal to metal contact
is sufficient and ample.
So why do I bring all this up? Because, The border fuel
rail does not utilize these mating surfaces per the fittings
designed intent. As such, (and not shown clarity and model
simplicity), the border fuel requires the use of an O-Ring
to provide your positive seal. Since there is no positive
stop, it is very easy to crush and extrude that O-ring to a
point where it will not provide a seal. 
Analysis TIME!
Here's a general overview from above. Nothing exciting here
really... you can see that the rail and fuel delivery looks
pretty good, eh? Or does it? 
Notice the flow trajectories in comparison to the inlet of
the Denso/Sard 850 Fuel injector? 
Let’s take a look from the top... Uh oh... No flow from this
view either... 
And a bonus shot 
Remember, at 45psi, none of this is a big deal. On your
stock car, you'd be fine with any fuel rail product. But
for those of us who modify our cars, we really need a fuel
rail that can provide fuel at worst case conditions. This
is where Damon and I picked up the ball and produced a
performance fuel rail that addressed all the discrepancies
we found through multiple analysis methods. We hope you
like our product. No later then next week, I will present you a flow analysis
of fuel injectors in the 300degree fuel rail. This will
relate to my original Fuel Injector Clocking technical
article. We will come full circle.
Petz #3
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TZR; Border Aftermarket Fuel Rail Analysis - 
