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: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.you are correct, they should require at least a science class before reading this message.
:
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