Discontinued Kubota Injector Lines

[TheOldHokie]

That ah dunno. It's too late tonight to do the math. That's trig, and that makes me have to think!

Anyway, I was going by what NIW posted:




If that number is accurate, AND if the pressure wave speed is the critical factor in the timing, then DIY tubing will be well within the parameters.

No trig - just basic arithmetic. A crankshaft rotating at 2000 RPM sweeps (360) x (2000) / 60 / 1000 = 12 degrees in a millisecond.

 

[TheOldHokie]

The following is excerpted from a scholarly paper on fuel injection system design. The red highlighting is mine.

So simple arithmetic says in an engine operating at 2000 RPM a millisecond change in signal propagation time will advance/retard SOI by 12 degrees CAD.

Diesel Fuel Injection
Magdi K. Khair, Hannu Jääskeläinen

Start of injection (SOI) or injection timing is the time at which injection of fuel into the combustion chamber begins. It is usually expressed in crank angle degrees (CAD) relative to TDC of the compression stroke. In some cases, it is important to differentiate between the indicated SOI and actual SOI. SOI is often indicated by an easily measured parameter such as the time that an electronic trigger is sent to the injector or a signal from a needle lift sensor that indicates when the injector needle valve starts to open. The point in the cycle where this occurs is the indicated SOI. Due to the mechanical response of the injector, there can be a delay between the indicated SOI and the actual SOI when fuel exits the injector nozzle into the combustion chamber. The difference between the actual SOI and indicated SOI is the injector lag.

Start of delivery. In some fuel systems, fuel injection is coordinated with the generation of high pressure. In such systems, the start of delivery is the time when the high pressure pump starts to deliver fuel to the injector. The difference between start of delivery and SOI is affected by the length of time it takes for a pressure wave to travel between the pump and injector and is influenced by the length of line between the high pressure pump and the injector and by the speed of sound in the fuel. The difference between the start of delivery and SOI can be referred to as injection delay.