Even numbers are tempting, but that causes the off 20x19 size. Nothing wrong with that on the other side.Nobody wrote:
I will probably interpolate this table into the 16x16
Even numbers are tempting, but that causes the off 20x19 size. Nothing wrong with that on the other side.Nobody wrote:
Yes, that's how it used to work. Nowadays, as Nobody was saying, cars have gone to returnless fuel systems. The pressure regulator is in the tank, one line comes out of the tank. The fuel pressure is static. It must be beneficial for emissions in some way. Dodge started using it on the Neons in '95.. It's been around awhile, that's a nearly 20 year old car at this point.kb1gtt wrote:It's very common that the fuel regulator is connected to the manifold pressure, such that the regulator tracks the manifold pressure. If you are at 5psia, your fuel pressure would be something like 50psia a difference of 45psi. Then if your manifold pressure is at 10psia, the regulator is supposed to adjust the fuel pressure to 55psia, such that the differential pressure remains 45psi. Or at least that's how the little hose off the top of your rail regulator is supposed to work. I tend to feel that's not not exactly what really happens, and I feel there are many dynamic issues with that kind of system. Any how, point being that the differential fuel pressure across the injector, for most engines is supposed to be reasonably consistent.
I’d suggest you use proposed table to calculate actual IFR (injector flow rate) used in S/D or MAF equations. The longer you stay in actual engineering units the better, because a multiplier followed by more multipliers makes it difficult to see where things are not solving as expected or what is causing tune/calibration to be off.Gotcha. So, just a curve by MAP. I will implement it as a multiplier and just set it to '1' by default.
Vol - liters. MAP - kPa. Temp - KelvinsNobody wrote: Speed Density in its simplest terms…
IPW = (Vol * VE * MAP) / (AFR * IFR * R * Temp)
* IPW is injector pulse width
* Vol is engine volume
* VE is volumetric efficiency i.e. 0.8 (for 80%)
* MAP is manifold absolute pressure
* AFR is air fuel ratio
* IFR is injector flow rate
* R is gas constant 287.05 J/(KG*K)
* Temp is absolute temperature (ideally a blend between IAT and ECT).
Code: Select all
The [url=http://rusefi.com/wiki/index.php?title=Engine:acronym-phrases#IPW]IPW[/url] is calculated based off the [url=http://rusefi.com/wiki/index.php?title=Engine:acronym-phrases#SD]SD[/url] equation.
Appreciate the example! Let me refactor the code so that I can write a unit test now.Nobody wrote:The result is 0.01414 sec or 14.14 ms.
I've made a tiny bit of progress, the numbers did match up - see test_speed_density.cppNobody wrote:A verified example is as follows.
Engine 7L (LS7 - 427)
IFR = 5.303 g/sec (42 lb/hr) each
R = 0.28705 J/g*K (we are now in grams)
Temp = 293.16 K (20C) - this needs to be blended…
MAP = 98 kPa
VE = 0.92 (92%)
AFR = 12.5 (engine is under heavy load)
The result is 0.01414 sec or 14.14 ms.
It really depends on how you want to do closed loop - narrow or wideband O2.russian wrote: I've made a tiny bit of progress, the numbers did match up - see test_speed_density.cpp
Do I understand it right that I would also need VE(RPM, MAP) and AFR(RPM,MAP) tables to actually get the ve and atf values for current conditions? Would 8x8 be enough for any of these or do we need 16x16?
I would guess we would eventually need both?Nobody wrote:narrow or wideband O2.
yep, that's the way we do it - window start and window angle width are both curves by RPM. I guess I will make an option to use either avg, max or min just for funE4ODnut wrote:range of angles that will vary depending on RPM.