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Pilot injection VS power

Diesel Tuning Fundamentals

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Discussion and questions related to the course Diesel Tuning Fundamentals

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How will the pilot injection affect the power and economy of the engine?

Will the diesel fuel in the pilot pulse do same good job as the diesel in the main injection pulse.

In the example in lesson "Pilot Pulse vs Diesel Knock", you have

Pilot 1, 0,8 mg

Pilot 2, 1,0 mg

Main 1,3. mg

But will the engine give more power or better economy if you give the main all fuel, 3,1 mg?

Will the engine start if you not code a new injector? Is there some identification error, or will it only be un-balanced fuel delivery?

Best regards

Anders N

Not a very good example do you think with a tiny amount of fuel injected?

Best is all ways to have one shot of injection but in order to do so you need sufficient end of compression temp to evaporate the diesel fuel and burn it efficient so depending on engine type and so on we turn off pilot from 150Kpa to about 170Kpa manifold pressure and on some low CR engines with massive big injectors we can not even run a single pilot as it will not idle even as smallest shot of fuel is about 10 microseconds of idle fuel.

Hi CR depend more on pilot injection.

Thanks, Ruud.

So the pilot injection can allow the main injetion to inject a larger amount of diesel by add more heat to the combustion chamber?

Is the pilot fuel map separated from the main fuel map? Or will the main injection be less if you increase the pilot injection, just to mainain the same total amount of fuel

For us pilot injection on HI CR engines is only for cold start and cosmetics to reduce idle & low engine load diesel noise/nock. Ones we have some engine load and boost we turn off the pilot injection for better power and fuel economy but shoots NOX sky hi but good thing is it’s brings soot down if you do it correct so your DPF has a bit more headroom for making bit more power.

I do not want to be involved in any OEM related stuff. The way I done it in the past is distract pilot mg/stroke plus Inj dead/response time from total fuel mass stroke demand so you can easy play with pilot injected fuel but we also use aftermarket diesel ECU where we have to set pilot and main injection in separate maps/settings. On some systems they do not even do any attempt to turn off pilot injection and that’s great for a load of injector return fuel running out of CR fuel pump capacity making a load less power but great for sales on bigger injection hardware as for injectors and fuel pumps so try to understand what your diesel wants and you will be reworded and on most modern diesels I do (less than 5 years last emission standards) fuel economy and power delivery go hand in hand.

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