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This image is needed for the injectoropening. http://www.vems.hu/files/Firmware/docs/EffectiveFlowrate.png Unfortunately it still does not show up in the manual. [http://megasquirtavr.sourceforge.net/manual/Detailed.Output.Fuel.html#Config [Manual: Detailed.Output.Fuel.Config]] '''Basic req_fuel calculation''' '''Assume''' * fuel density=0.755 g/cc * AFR=14.7 at stoich * intake air density = 0.0012 g/cc (at MAP=100 kPa, which might be a cheat from the real 101..104kPa ?) * (alternate+1)*divider = N (see N below) '''Input data''' * '''I''' injector flowrate (cc/min) * '''D''' engine displacement (cc) * '''N''' number of injectors (piece, eg. 4 for a 4 cyl port injection) req_fuel = D / N * 0.0012 / 14.7 / 0.755 / I * 60000 The constant 60000 is responsible for scaling output from min (coming from the injector cc/min) to msec unit we usually use for this. The other constants are self-explanatory. '''Simplified equation is: req_fuel = 6.49 * D / N / I''' '''Examples''' ||'''D''' || '''N''' || '''I''' || '''fuel pulsewidth (msec)''' || '''req_fuel=0x..''' || || 1600 || 4 || 220 || 11.8 || 76 || We usually use 50% of calculated req_fuel and scale up VE values (j[] table) to double values (max values around 200, not 100) for somewhat higher precision. Note: ''bin/req_fuel.pl'' in firmware has a bit more featureful calculator, and there are many on the web. ---- Tuning software support. PSITuner implements a tool to calculate the req_fuel. In the Tools menu select "Fuel Calculations" http://www.vems.hu/files/hackish/fuelcalc.gif I just changed this to account for adding boost but Jorgen suggested that it's already taken care of. I'm not sure the right answer here as experimentally I found req_fuel=0x0d worked perfectly. As you can see the example screen cap yields a very similar value... ---- '''See also''' * PortInjected/FuelInjectors * GenBoard/VerThree/LowZInjectors * OnlineCourse/InjectorOpening (advanced info for developers)
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