mileage computer for a carbureted engine

[TheDon]

any updates John? I'd love something for my mercedes too!

[dcb]

I do have something that is pretty cheap in mind for the mechanical diesels, but you have to install a throttle position sensor and a rpm or pump rotation sensor and a speed sensor, and I or someone has to teach the guino how to make sense of it.

I'm also thinking about just using a function like speed/(throttle position*rpm) for my bike too, to see if it is reasonably accurate.

[LostCause]

Originally Posted by dcb

Ya, das Durchflußgeber ~$61 http://www.conrad.de/goto.php?artikel=126055

The low end of the flow wasn't small enough for my liking
0.025 - 2.5 l/min

Auf.

I don't know the precision you want, but the only thing I've found in that range are micro flow meters. They use a funky "nutator" to measure down to 0.005l - 0.25l/min. They may be hard to come by, though.
_________________

I don't know the accuracy or whether they'd work with gasoline, but these are the smallest "cheap" flow meters I've found. They are all the vane type and are intended for computer water cooling.

The only information regarding resolution is "0.1l/min @ 1000rpm." Might be worth a look...they are cheap enough.

Innovatek Flowmeter Rev. 2.0


- LostCause

[diesel_john]

Originally Posted by dcb

I do have something that is pretty cheap in mind for the mechanical diesels, but you have to install a throttle position sensor and a rpm or pump rotation sensor and a speed sensor, and I or someone has to teach the guino how to make sense of it.

I'm also thinking about just using a function like speed/(throttle position*rpm) for my bike too, to see if it is reasonably accurate.

the cam pulley or pump pulley bothe have 6 or 8 spokes in the pullies. and they are steel so would be a good candidate for an old cam position sensor.


The only information regarding resolution is "0.1l/min @ 1000rpm." Might be worth a look...they are cheap enough

How cheap are they? my flow range is 0.1 gal/hr to 3.0 gal/hr.
When i get the two cylinder going the range will be about half that.

[LostCause]

The watercooling flow meters would be a total shot in the dark. Since most of them are made in the EU, they used to be cheap.

Innovatek Flow Meter Rev. 2.0 - $45 (€30)

Most legitimate fuel flow meters I've found are intended for constant flow applications (aviation, marine). They require pulse dampeners, lose accuracy with fluctuating flow rates, and are expensive. The smallest one I've found is rated at 0.3-30gph.

Floscan 201A-6 - $110 ($148 w/ pulsation dampener)

Another cheap solution might be employing a MAP and IAT sensor to calculate MAF. If you can calculate the AFR to any reasonable accuracy, the fuel rate can be determined.

- LostCause

[JamesLaugesen]

Hi everyone, my first post here, I've read through this thread with great interest, some real cool experiments happening.

Thought I'd propose some non-mechanical ideas for measuring flow:

A venturi meter.
Along the lines of this:
http://hyperphysics.phy-astr.gsu.edu...s/venturi.html
Of course with something clever to observe the pressure differential as a signal.

Inertial meter, or coriolis, whatever you want to call it.
Best description I can find is good 'ol wikipedia:
http://en.wikipedia.org/wiki/Coriolis_flow_meter
Need some imagination to use it in a vehicle, especially a bike, but at least the engine could provide a good consistent vibration.

[TheDon]

air fuel ratio? might be hard in an Indirect Injection engine since the fuel is mixed post turbo in the prechamber(in the head)...

sigh... yet another pitfall of owning a mechanical injection car... gotta make sacrafices..



I did have an idea though. What if you could monitor injection pulses to the injectors (which is how the injection pump can be timed) and set up an equation that would output the mpg...

like... pulses at idle and the variable would be your IP rev's which are half that of the engines rpm... all you need to know is the amount being injected at all rpm's for the equation, monitor the injector pulses and wing it on the fuel return.


my 1985 300D turbo, which is the oddball year, has an EGR computer. I have no idea what it does since I removed the EGR from my car .. man it gunked up the intake and valves.

[diesel_john]

diesel timing lights use a small piezo- electric ring which clamps around the injector line and actually outputs a charge signal during the expansion of the injector line when the high pressure builds up prior to injector pop off. I was able to view the entire injection pulse on a scope. gas grill igniters, knock sensors all use the same technology.

But the the pump rpm and throttle position is the best for a non turbo'd, non governed diesel.
The turbo'd and speed governed have mechanisms within the pump that change fuel delivery independant of accelerator position. on the turbo if you disconnect the intake manifold pressure feedback to the injector pump the pump won't know that the turbo is producing more pressure and it will not increase the fuel above the accelerator positon.

An interesting footnote to the differences in gas and diesel was observed the other day. When i go down a hill to pick up speed with the diesel, i have to let off the accel. pedal or the engine uses more fuel as the rpm increases. Mileage does not increase like a gas engine, during vacuum increase. And in fact decreases because of more aero loss.

[diesel_john]

I put three beads the the flow meter, and it counts all three, but makes the instant mpg more jumpy during low flow. Average mpg settles down. the beads seem to go around together at low flows but spaceout during high flows. i am hoping they provide just enough more resistance at low flows to keep moving and increase the flow range. have not tried a bench calibration yet.

[diesel_john]

fuel returns to the holley float bowl as the drawing in post 61. pics in my album.
i am trying to determine if my injector pump has any governing function during partial rack.