mm3 ???
- Thread starter walsh450mx21
- Start date
not exactly. And I don't mean to confuse anyone. It does not translate exactly to a specific volume. It translates to a volume reference. IOW 20 mm^3 is not necessarily double the 10 mm^3 as injected fuel. it is a minor misnomer.
Would you mind elaborating please? I think I'm gonna learn something technical today.
Is it a "call" for that amount of fuel and what you are saying is that even though it (the programming you have input - ex. 20mm3 vs 10mm3) is saying to inject 20mm3 in XXXXus, it may not be able to physically do that therefore, its not really injecting that amount even though you are calling for it? BUT if there is enough time and physical capacity, it will inject twice as much fuel (talking about volume here) if changed from 10mm3 to 20mm3???
Just tryin to learn somethin.....
I don't quit follow you. I do realize as fuel is injected other calculations take place that control quantity. Could you elaborate?
But mm3 is a quantity is it not?
The "reference" is commanded by the TPS (throttle based) table. But this does not actually define a fuel quantity, though that is the implication that the Kiwis built into the GUI.
You get, say, 100 (i'm going to leave out the units to make this easier) from the TPS table at WOT. You take that to the fuel pressure table, and then you take that fuel pressure to the pulse table. Now you have a pressure and a pulse definition, which together is what determines the actual amount fuel injected. Duration and pressure will define how much fuel is sprayed.
You can change up the fuel pulse table, say, double everything, so that you get a 3000 us pulse instead of a 1500 us pulse. That is clearly double the amount of fuel injected, but it is still reflected as 100 mm^3, (not 200). It will even still log as 100, though the truck is draining the fuel tank faster than ever.
That is why I wanted to clarify. I think the EFI guys should have written it a bit different to eliminate this confusion. The TPS table should not reflect units as mm^3, but rather a unitless fuel reference...IMHO
You get, say, 100 (i'm going to leave out the units to make this easier) from the TPS table at WOT. You take that to the fuel pressure table, and then you take that fuel pressure to the pulse table. Now you have a pressure and a pulse definition, which together is what determines the actual amount fuel injected. Duration and pressure will define how much fuel is sprayed.
You can change up the fuel pulse table, say, double everything, so that you get a 3000 us pulse instead of a 1500 us pulse. That is clearly double the amount of fuel injected, but it is still reflected as 100 mm^3, (not 200). It will even still log as 100, though the truck is draining the fuel tank faster than ever.
That is why I wanted to clarify. I think the EFI guys should have written it a bit different to eliminate this confusion. The TPS table should not reflect units as mm^3, but rather a unitless fuel reference...IMHO
Thank you for your explanation. I do agree with you on reference to mm3. As far as time the injector is open, I would like to add that doubling injector time open doesn't mean you get double the fuel.
I don't know Ben, lets figure it out. I get 20 mpg when I am running 15 mm^3. Does that sound right to you, if so, we can do a conversion and see.
I second that. Lets start a thread that can be eventually changed to sticky that discusses and explains these relationships and considerations.
See, you got something started.... :cool2:
I wonder, you say compressibility, do you mean pressure? Liquid i not compressible?
everything is compressible. True, we make assumptions in theory study to make things easy on ourselves. At 23,000 psi, liquids compress. I can't begin to tell you how much, but it is not trivial at those pressures.
What kinda truck do you operate that only requires this volume of fuel at a cruising range. I wonder if the pressure and time has been changed to allow more fuel than this enter the cycle.
I certainly won't argue with you relating to compressing a liquid. That's beyond my concern. I will say at 23000 psi compressing a liquid won't gain any more space for further volume.
What do you mean? Let's get your question answered. The question was, what is mm3 on the side of some tables. One side of a table is an axis x, and the other side ( top in this example ) is a y axis. mm3 x is the same as saying cubic inch, mm3 is the a metric system and cubic inch is a SAE system in regards to volume. There are not any numbers in your question to reference or convert a volume in millimeters cubed to anything else. If this doesn't answer your question, could you elaborate with your question!
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