mileage computer for a carbureted engine

[dcb]

Hey Yoshi, what do you think about a mass flow sensor in a liquid? too heat conductive?

[dcb]

hmm... well there are thermistor liquid flowmeters for things like blood flow in an artery:
Digital temperature compensation of a thermistor flowmeter

[dcb]

Here is an interesting read for possibly a solid state solution:
http://www.sskteracon.com/ExternalFiles/AN685.pdf

[wyatt]

When I was in college we used a flow meter like this for a lab once.



The fluid pushes up on a ball that is more dense than the fluid you are working with. You can calibrate it to take eye readings (with a glass tube), or use some sort of dual or triple coil system to determine the location of the (usually ferrous) ball by determining magnetic field in the coils. It may sound hard, but I remember it being pretty easy. We were getting fantastic results with water, but it should work for gasoline as long as your materials can withstand the environment.

EDIT:
These are called rotameters or area meters. I haven't found any that will just give a quote that have a reasonable cost, but most are made from stainless and glass. I did find one that was about right, but I guarantee it is way to expensive. It has low flow readings (one model as low as 0.02 gph; my 1.3L idles at ~0.2 gph). They also have ouptuts from 4 to 20 mA, which should make them usable without modification. ROTAMETERS with electric output. DATA SHEET.

[moorecomp]

Hey guys,

How about measuring the differential pressure across a restriction in the fuel line. No flow means equal pressure across the restriction, the higher the flow the greater the differential.

Low Cost Wet/Wet Differential Pressure Sensor

[wagonman76]

Good find. I think it could work well with the mpguino. One would have to change some of the programming. Or just build a circuit to make the sensor run a 555 timer chip to create pulses for the mpguino to read, pulses that are variable based on the input voltage that varies with pressure.

[moorecomp]

Wagonman,

One thing to consider, the fuel pressure would have to be a constant pressure, regardless of the flow. A fuel pressure regulator, if not already installed, looks like it could be had for $20 or so.