How quickly measure fuel consumption?

Submitted: Monday, Feb 04, 2008 at 16:59
ThreadID: 54232 Views:2697 Replies:8 FollowUps:11
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“Standard” way is to reset odometer, fill up to lid and check odometer at next refill. Takes too long to be accurate. Anyone has any tricks to speed up process? I have 80 series 1HZ diesel.

Cheers
Serg.
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Reply By: hotfishez - Monday, Feb 04, 2008 at 17:30

Monday, Feb 04, 2008 at 17:30
In line flow meter?
AnswerID: 285571

Follow Up By: KSV. - Monday, Feb 04, 2008 at 17:33

Monday, Feb 04, 2008 at 17:33
How about return line? Not so easy, I am afraid.

Cheers
Serg
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FollowupID: 550547

Follow Up By: wigger - Monday, Feb 04, 2008 at 17:54

Monday, Feb 04, 2008 at 17:54
How can it take too long?
Go to servo
Make sue vehicle level
Fill up to first click
Set Odo at zero
Drive 20, 40kms -further if you want better accuracy
Go to servo and fill up to first click
Divide no of kms travelled into 100
Multiply this figure by no of litres
This gives litres per 100km (the recognised standard)

Can't see that that would take long. Might help to start in NSW and finish in Qld then no time at all
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Follow Up By: KSV. - Monday, Feb 04, 2008 at 18:07

Monday, Feb 04, 2008 at 18:07
20-40 km will return pretty inaccurate figure. 50+ litters of burned fuel will give better result and obviously only can be done quickly on freeway, not in city. Plus factors like cold car in the mornings, heavy traffic, use aircon etc.

Serg
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FollowupID: 550563

Follow Up By: hl - Tuesday, Feb 05, 2008 at 09:39

Tuesday, Feb 05, 2008 at 09:39
"Quickly" is not possible in a 1HZ diesel... maybe if you turbo it.......;-)

Cheers

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Reply By: Max - Sydney - Monday, Feb 04, 2008 at 17:35

Monday, Feb 04, 2008 at 17:35
What's your hurry?
AnswerID: 285573

Follow Up By: KSV. - Monday, Feb 04, 2008 at 17:46

Monday, Feb 04, 2008 at 17:46
Simple. If you do something trying to improve your fuel consumption it would be nice to know what you are getting ASAP. Plus I have two sets of rubber and changing them often. Because they differs in diameter odometer reading and therefore fuel consumption getting skewed.

Cheers
Serg.
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Follow Up By: Member - Oldplodder (QLD) - Monday, Feb 04, 2008 at 18:28

Monday, Feb 04, 2008 at 18:28
Problem is keeping all of the conditions the same.
Same road, same traffic, same throttle settings, same temperature, same wind (head or tail) or drive same distance there and back.

So maybe do as suggested above and fill to first click at a highway servo not too far away, do 50k down and back then fill to first click.
Maybe use cruise control so same throttle is used on the same hills.
Maybe the same time at night to minimise traffic.

Would guess it would only pick up major differences over 10% though :o)

I have done similar measurements going Brisbane to Gold Coast when working there. Took figures every few days over a period of 6 months and found it varied from 9.3l/100k to 13.4l/100k. Traffic, headwinds and speed made that much difference.
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FollowupID: 550572

Follow Up By: Member - Oldplodder (QLD) - Monday, Feb 04, 2008 at 18:29

Monday, Feb 04, 2008 at 18:29
Ps - forgot to mention, one thing I was also playing with was tyre pressures so see what difference it made.
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Follow Up By: KSV. - Monday, Feb 04, 2008 at 20:56

Monday, Feb 04, 2008 at 20:56
Hi Oldplodder,

you are spot on. It is very difficult to measure accurately due to numerous factors you have mentioned. Thus only big difference became noticeable.

Cheers
Serg
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FollowupID: 550628

Reply By: disco driver - Monday, Feb 04, 2008 at 18:28

Monday, Feb 04, 2008 at 18:28
Hi Serg
There was a post on this subject a week or so back with lots of good suggestions. Worth searching for it.

I would point out that any fuel check over less than 1000km or so only applies to exactly the conditions on that day.

Things like ambient temperature, relative humidity, wind speed and direction, tyre pressure, vehicle load, different driving conditions (traffic density etc), drivers mood, color of his jocks and socks and so on all have a bearing on fuel consumption.

Sorry,there is NO short cut way of doing it with any degree of accuracy.

Disco.
AnswerID: 285583

Reply By: Robin Miller - Monday, Feb 04, 2008 at 18:35

Monday, Feb 04, 2008 at 18:35
Hi Serg

There is a way which I think is (but not sure) compatiable with your car.

I have used this way on my 4800 Patrol , but as per Peter and others have said it relates to the specific conditions.

The way is to measure the pulse width at the injectors , this equates to the time that they are open and hence directly to fuel use.

Jaycar sell a kit for this.

In reality do not expect better than about 5% and the conditions do have to be the same including the time the engine has already been running because some do not have constant fuel pressure which directly affects the result.
Robin Miller

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AnswerID: 285585

Follow Up By: KSV. - Monday, Feb 04, 2008 at 20:57

Monday, Feb 04, 2008 at 20:57
Thanks - mine is diesel :-)

Cheers
Serg
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FollowupID: 550629

Reply By: Steve M - Monday, Feb 04, 2008 at 20:00

Monday, Feb 04, 2008 at 20:00
Its been a while since i did this for a job but im sure you can measure fuel consumption almost instantly on a dyno by measuring the CO,CO2 and unburned hydocarbons. This is the only "quick" way I know of doing it and takes some very expensive gear to do accurately..

Steve M
AnswerID: 285617

Follow Up By: KSV. - Monday, Feb 04, 2008 at 20:59

Monday, Feb 04, 2008 at 20:59
Thanks - good though expensive hint.
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Reply By: HGMonaro - Monday, Feb 04, 2008 at 20:58

Monday, Feb 04, 2008 at 20:58
or buy a Scangauge II (if your car can operate it...) and after a calibration tank or so, you can have a pretty accurate Trip Computer.

Nige

P.S. I doubt an 80series has the connector... I don't know anything about them :)
AnswerID: 285637

Follow Up By: KSV. - Monday, Feb 04, 2008 at 21:03

Monday, Feb 04, 2008 at 21:03
80 1HZ pretty much mechanical - no engine ECU, so not good :-)

Cheers
Serg
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FollowupID: 550632

Reply By: Member - Chris R (NSW) - Monday, Feb 04, 2008 at 21:43

Monday, Feb 04, 2008 at 21:43
As a very rough measure in remote driving, fill ot outset of journey and after 200km or other useful distance dispense jerry cans until tank is again full, then measure fuel remaining in can and calculate. Good final check on what's happening real time.

Chris
AnswerID: 285655

Reply By: Member - Bucky (VIC) - Tuesday, Feb 05, 2008 at 07:33

Tuesday, Feb 05, 2008 at 07:33
Fuel consumption is not measured quickly.
I do not believe that these km/lt indicators on new vehicles are in any way accurate.
There are a million variables, and can be too easily set up, or adjusted to suit the occasion.
Best way is to look at the big picture and include all types of terrain and conditions.
If you are just doing highway work, its simple, but remember in hills, your vehicle is working harder anyway.

The old fashioned way, is the best way, and just do not stop at one tank either
Cheers
Bucky
AnswerID: 285711

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