Fuel consumption display

[Acetronics2]

Hi, Servo

You're right, fuel pressure keeps steady ... so, just measure how long your injectors are open, make a "real life" calibration ( how much fuel vs total injectors "bleeding" time ) and that's it ...

It's very simple ... just look at fluid mechanics laws for quasi-ideal liquids, and you'll see volume is a function of time and pressure @ 99.99% !!!

so, you just have to measure the pulses driving your injectors ... just 5 wires to wire !!!

Alain

[calzaman]

I am trying to calculate fuel consumption as a function of RPM. So for a given rpm and an engine size I can fetch the approximate fuel consumtion (liters per minute). Does any one know of an equation that can achieve that.

Also your equation which you have used (Fuel consumption (liters/100km) = (RPM * injector open time * injector flow) / speed * 100000) is quite good and it is working for me. However, do you have a reference for where you got the equation for. Also is the 8 ms a standard for flow open time for all engines.

Thank you kindly for your help

[Tobias]

You will be closer at guessing the next lottery numbers than using just RPM to measure fuel consumption. You need to know BSFC and AF ratio as a starting point.

[rshaver]

Just a thought but if you can get 2 fuel flow sensors you can get a pretty accurate reading. You have to get the flow in and out of the system and then just do a little subtraction. Can't remember where I saw it. But someone did this and it worked over all driving conditions. If you have a flow of 5 gallons per hour(GPH) in and 3GPH out then you are using 2GPH. Or what ever measure you use. You get the in and out because the injection system has a return line to the tank for the fuel not used. Only problem with this is trying to find the flow sensor. I have been trying to find just one for my old truck and they seem to be non-existent now. They used to be every where.

[Tobias]

The flow sensors we use in drag racing are about $2000!!! They are deadly accurate but very pricey.

[ardhuru]

Guys, I'm no authority on this, but if that data is available on the OBD2 connector in your vehicle, how about just getting a bluetooth OBD2 adapter, and couple it with a tablet/phone running Android (App: Torque)? Would be an inexpensive, and easy solution.

[calzaman]

Thanx.

BUt what I need is an approximation. I understand that there is no way to caclulate the fuel consumption because of the acceleration, deceleration, and load. However, if you are calculating fuel consumption at a constant speed, then wouldnt there be an equation to calculate the fuel consumption.