- 10,350
- 74
- 48
- Location
- Meadows of Dan, Virginia
The Fuel "density" compensator on the multifuel responds to changes in the viscosity of the fuel and adjusts fuel delivery accordingly.
For the fuels specified in the TM's, the viscosity is directly proportional to the heating value so when this adjustment is made the engine power output remains essentially constant for a given position of the accelerator.
This is a problem for biodiesel/veggie oil since its heating value is lower but is more viscous than diesel. The FDC reduces the fuel delivery when it should increase it for constant power.
Yesterday I was recording the position of the fuel stop block(potentiometer in FDC, image below) and noted that it increases delivery as the biodiesel is heated and when the fuel temp was about 115F, then the position of the stop block was the same as for regular diesel at room temp. I didn't heat the fuel any further.
It also suggests that heating regular diesel fuel will increase the fuel delivery.
So by heating the biodiesel, the problem with the FDC may be circumvented.
NOTE: I say "may" because the tests are not conclusive, the temperature of the FDC itself was not monitored and if it compensates for its own temperature rise then it will eventually all go back to square one.
I'm amazed at how sensitive the FDC is though, just a few degrees change in fuel temp (=viscosity) causes a reaction.
Fun stuff!
For the fuels specified in the TM's, the viscosity is directly proportional to the heating value so when this adjustment is made the engine power output remains essentially constant for a given position of the accelerator.
This is a problem for biodiesel/veggie oil since its heating value is lower but is more viscous than diesel. The FDC reduces the fuel delivery when it should increase it for constant power.
Yesterday I was recording the position of the fuel stop block(potentiometer in FDC, image below) and noted that it increases delivery as the biodiesel is heated and when the fuel temp was about 115F, then the position of the stop block was the same as for regular diesel at room temp. I didn't heat the fuel any further.
It also suggests that heating regular diesel fuel will increase the fuel delivery.
So by heating the biodiesel, the problem with the FDC may be circumvented.
NOTE: I say "may" because the tests are not conclusive, the temperature of the FDC itself was not monitored and if it compensates for its own temperature rise then it will eventually all go back to square one.
I'm amazed at how sensitive the FDC is though, just a few degrees change in fuel temp (=viscosity) causes a reaction.
Fun stuff!
