Quote:
Originally Posted by diesel_john
theoretical pressure curve
Actually the curve will have high frequency noise superimposed upon it. A low pass filter, move the transducer up and down a straight section until the minimum noise is observed. I don't want to say look for a node line... The ear is good frequency analyzer and the entire event can be heard with a mechanics stethoscope.
Notice the pickup has two piezo's, and they oriented opposite each other, side to side motion will be cancelled somewhat, since piezo's have polarity. but the expanding tube will produce plus or minus voltages in both at the same time.
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I need a setup like that for running a timing light on my diesel. My custom engine has no real way to set timing. I built it from a combination of parts from different era engines, such that there were no timing marks for the pump. It is working well but I just set it by ear. It has been bugging me to know what the timing really is.
As for mileage of a mechanical pump the only way you are going to do that is with a flow sensor like your zemco. The return line will be a problem because not only does it take the bleedby from the injecters(most of these injectors are a machined tolerance fit(no orings)) but it also takes bypass fuel from the pump to keep it cool. If you bring your return line back and T it in front of the zemco(engine side) you will need to cool it with a transmission cooler or something. The volume of the cooler should not affect accuracy of the zemco at all as long as it doesnt have an air pocket. Even with an air pocket only the instant mpg my fluctuate but the rest would be fine.
Also if you operate in very cold climate you might need a heater in your fuel tank to keep the diesel from gelling. The return line also helps warm the tank a bit in cold weather.
To do this right you really need two flow meters similar to the zemco with a logic board that subtracts the return line pulse's from the supply pulse. Unfortunatly I am not an electronics engineer so I am not sure how to design the logic board or it would be done already.