How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
(OP)
Hello,
We are going to test a small 2-stroke engine (150cc) on a eddy current brake installation with data aqcisition system connected to it.
This simple engine is still using a carburetor with no fuel pressure from the tank.
So we are looking for a device or a way to measure the fuel consumption during a cycle test (NEDC for example)
Difficulties: very low fuel flow, no real fuel pressure, accuracy must be under 1%, fuel is petrol mixed with lubrication oil.
- Are coreolis flowmeters the only option for us?
I hope there are also other options the might be cheaper.
Hope to hear some tips and tricks for people over here.
Thanks in advance!
We are going to test a small 2-stroke engine (150cc) on a eddy current brake installation with data aqcisition system connected to it.
This simple engine is still using a carburetor with no fuel pressure from the tank.
So we are looking for a device or a way to measure the fuel consumption during a cycle test (NEDC for example)
Difficulties: very low fuel flow, no real fuel pressure, accuracy must be under 1%, fuel is petrol mixed with lubrication oil.
- Are coreolis flowmeters the only option for us?
I hope there are also other options the might be cheaper.
Hope to hear some tips and tricks for people over here.
Thanks in advance!





RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
Best to you,
Goober Dave
Haven't see the forum policies? Do so now: Forum Policies
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
Best to you,
Goober Dave
Haven't see the forum policies? Do so now: Forum Policies
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
----------------------------------------
The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
http://en.wikipedia.org/wiki/Burette
Terry
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
The method with the weight scale, burret and stopwatch I knew. But for a transient measurement, connected to other measurements (temperature, pressure, exhaust emission), it is not the best method because it's hard to combine those measurements afterwards in x,y graph.
So I want to measure it electronic and also transient, so I can measure and record it with my data acquisation system.
- With turbine flowmeasurement devices you have most of the time 3% inaccuracy.
- Don't know much about electric or magnetic measurements, maybe they are good, but also maybe just as expensive as a coreolis measurement flow-device..?
- precision zero pressure drop flow meters are new to me, tried to search more information about it on google but couldn't not find much about the principle and prices
Maybe other persones have experience with this type of fuel flow measurements on carburetor engines?
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
----------------------------------------
The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
I suppose you could automate the burette method with a couple of transparent tubes, four or so solenoid valves, and a couple of meniscus sensors. You'd still get discretized data, e.g. x seconds to drain from high sensor to low sensor, and it would still be delayed by the carb float as noted, but it would be pseudo-real time.
If the fuel is dirty enough (real reference fuel may not be, but retail fuel might), you could put a laser anemometer in the fuel line, I guess. Still subject to float delay. ... which should be treatable as a phase shift when you are screwing with the data.
Mike Halloran
Pembroke Pines, FL, USA
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
As to delays in the carby, you would need to monitor float level and therefore changes of fuel in the float chamber.
Real time weight loss from the tank and real time float level gives enough data to calculate real time usage I would think.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
Tekton
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
http://helicalcamshaft.com/index.php?option=com_co...
No attempt was made to measure the amount of fuel used - the test was a comparison of the time the engine would idle on the same volume of fuel. But clearly the amount of fuel used could be measured easily enough.
Sometimes the simpler methods are more effective without recourse to electronic gizmos.
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
Meanwhile I have also had contact with several suppliers and received some interesting options:
http://www.massflow-online.com/cms/wp-content/uplo...
DFM-50A-K
http://www.massflow-online.com/shop/index.php?main...
Model: DFM-50A-K
Min: 1 l/h
Nom: 25 l/h
Max: 50 l/h
Engine: 80 (kW)
http://www.bronkhorst-cori-tech.com/files/br_corit...
Coriolis flowmeter: http://www.bronkhorst-cori-tech.com/files/br_corit...
Only, the problem for me is to determine what fuel flows will I reach and with which pressures I have to deal with (carburetor, 150cc 2-stroke engine).
I have done a calculation and based upon 1 hour of doing this test cycles the engine 'drives' virtually 22 km, with lines up with 1L of Petrol usage. So fuel flow is based upon this calculation 1L = 711 gr/hr
Can someone else confirm this? Or do they of other numbers? (just to make a comparisson)
But what pressures should I think of with a carburetor? When the fueltank is 5L = 3,5kg
The diameter of the fuelhose is 3~4mm (= 0.137 inch)
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
Under certain conditions it is only 1% but I planning to test also a lot with lower flows then 1L/hour.
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
EFI systems do this, and the air-mass sensor is a standard and relatively cheap component.
To compensate for the fact that the engine doesn't burn 100% stoichiometric, measuring the CO-percentage at the same time would give you a correction factor.
Benta.
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
Besides that, I think this is more suitable for a 4-stroke, a 2-stroke engine has stil a lot of oxygen in the exhaust, and CO, HC, etc.
RE: How to measure fuel consumption (flow) with a small carburetor 2-stroke engine
Expensive? Don't think so, this is standard automotive technology used in millions of cars: air-mass sensor and Lambda probe.
Benta.