Does less fuel save fuel and do you get more if the fuel is cold ?

[grasmere]

Does half or third filling a tank save fuel because the vehicle is lighter (long journeys excluded and assuming you live next to a garage so its no hardship to fill up )

Will buying fuel early morning get you more fuel than later in the day when its expanded as the ambient temperature rises

Just a couple of thoughts I saw on a different forum

Answers on a small postcard . . .

 

[andy_k]

I was told by a wise old mechanic that 3/4 was the optimum level for fuel as it's about as high as most people ever fill their car it saves you washing all the rust etc off the insode of the tank should you fill too far. When the fuel is low there is a possibility of condensation forming inside the tank which can affect the fuels quality.

My guess is that any change in volume will be so small it won't matter and at the end of the day it is still a gallon and will have the same energy properties.

Andy

 

[MikeL]

Save fuel

Hi all,

It is likely that any saving by carrying less fuel will be more than offset by the increased visit to the petrol station, which regardless of location will require an extra starting of the engine - the least fuel efficient time.

70 litres of fuel weighs approx 52Kg

Regards

Mike

 

[Benzowner]

Hi all,
70 litres of fuel weighs approx 52Kg

Regards

Mike

52kg is about 8 and a bit stone, leave the Missus at home, same thing

 

[DITTRICH]

...assuming the fuel weighs 50kg and the car weighs all in then 1,500kg i'd guess that in stopstart driving conditions, savings might be 50/1500 = about 3% . In constant speed situations it would not make any difference. All this is making big assumptions.

...the tank sits underground and the temperature wouldn't vary very much unless there was a prolonged cold spell. If I recall accurately, liquids don't expand / contract very much to make a noticeable difference.

...just upend and shake the fuel nozzle a bit so the last bits trickle out is the best you can hope for. The really variable bit is how the pump measures the fuel it give you.

Rgds

Les

Les

 

[grasmere]

...just upend and shake the *** nozzle a bit so the last bits trickle out is the best you can hope for.

I know what you mean - its an age thing

 

[Shude]

I was going to explain my normal process for getting maximum fuel into the tank but it actually read like manual for lovers, so I'm not going to bother

 

[grasmere]

but it actually read like manual for lovers,

I'm guessing that was the part where you throw the hose over your shoulder for maximum effect . . .

 

[Shude]

I'm guessing that was the part where you throw the hose over your shoulder for maximum effect . . .

It was all to do with withdrawing the nozzle and re-inserting slightly shallower and rotated for maximum delivery, but it just didn't read right

 

[portzy]

If I remeber correctly. A liquid will expand or contract by 1/273 for every 1 deg temperature rise / fall. I guess as someone said ealier that because the storage tanks are underground then the temperature would be fairly constant. Also, I imagine there will be a tempearture spread that fuel will have to be so combustion is unaffected.

If you bought say, 20 gallons?, bunged it into an industrial freezer for a few hours, it cooled, it shrunk, and therfore condensed and became denser, what would you have?. Slightly less than 20 gallons is what you would have but the Heat Value of one new 'notional gallon' would be higher.

So, if the engine controls fuel flow based on volume and you somehow managed to give it some 'denser' fuel then the theoretical effect should be overfuelling therefore a rich mixture (bad).

If you could somehow buy some REALLY super chilled fuel you would have store it somewhere warm to acheive a financial benefit and by the time you have gone through all this mallarky you really ought to be thinking about getting out more.

Portzy.


PS. It does work better with gases though, especially Methane, but you dont want to know about that.

 

[nickmann]

...

So, if the engine controls fuel flow based on volume and you somehow managed to give it some 'denser' fuel then the theoretical effect should be overfuelling therefore a rich mixture (bad).

...

That would work on an open loop system, the same result can be had by tweaking the throttle position sensor. These days though systems are closed loop - meaning the fuelling gets adjusted by what comes out if the exhaust based on the sensors there. As sson as the exhaust sensor passed a reading that showed a rich mixture then the ECU would put less fuel in.

 

[glojo]

This thread is sad, but in the nicest possible way.

I am in terrible pain, but it has cheered me up no end reading it.

Well done.

So...... what should the optimum temperature of the fuel be when refueling? Should the fuel tank be chilled?
How much energy will be used chilling the tank?
and would the costs outweigh the chilling effect?
Should the nozzle be held in the left hand, or right?

Regards,
John

 

[portzy]

That would work on an open loop system, the same result can be had by tweaking the throttle position sensor. These days though systems are closed loop - meaning the fuelling gets adjusted by what comes out if the exhaust based on the sensors there. As sson as the exhaust sensor passed a reading that showed a rich mixture then the ECU would put less fuel in.

Thats why you are an Engineer?, and I am a Gas Man . Yep, youre right, I was going back to my carburetter days. Must get an industrial freezer then

Portzy.

 

[portzy]

This thread is sad, but in the nicest possible way.

I am in terrible pain, but it has cheered me up no end reading it.

Well done.

So...... what should the optimum temperature of the fuel be when refueling? Should the fuel tank be chilled?
How much energy will be used chilling the tank?
and would the costs outweigh the chilling effect?
Should the nozzle be held in the left hand, or right?

Regards,
John

John.

I think this thread has all the potential to become even sadder

From the reatailers point of view the hotter the better as the fuel will expand and the calorific value per unit volume will reduce. From our point of view the colder the better for the opposite reasons. I imagine, as I said, there will be a 'spread' of temperature which fuel has to be stored and transported at because if you are dealing with thousands of gallons then expansion / contraction is a real factor if you are selling by volume.

I guess all costs involved in Chillin' would be lost on any gains from a twenty gallon point of view but, take Concorde for jollly, and it would be different.

Its a little known fact that energy suppliers have to adjust there stated calorific values to take into account variancies from the ISA and quote the CV based on actual data.

So, to answer your points and from the motorists point of view:-

Cold fuel
Plastic fuel tank (more temperature stable)
Purchased in the Arctic
Transported from the Sahara
Burnt in Yorkshire

Portzy.

 

[glojo]

So, to answer your points and from the motorists point of view:-

Cold fuel
Plastic fuel tank (more temperature stable)
Purchased in the Arctic
Transported from the Sahara
Burnt in Yorkshire

Portzy.

Ouch Brilliant answer but why would I burn the fuel in Yorkshire, surely that would be enviromentally anti-social?

Ferrari chill their fuel to get more into their tanks, but it certainly did not do them any good this week-end

How much fuel would I use getting to the nearest fuel station in the artic and......... Just joking, sorry.

John

 

[portzy]

Ouch Brilliant answer but why would I burn the fuel in Yorkshire, surely that would be enviromentally anti-social?

Ferrari chill their fuel to get more into their tanks, but it certainly did not do them any good this week-end

How much fuel would I use getting to the nearest fuel station in the artic and......... Just joking, sorry.

John

I guess Yorkshire is kinda middle for diddle in a middle for diddle temperate country which is middle for diddle twixt the Arctic and the Sahara. But, you're right, we're still cleaning the soot from the walls of houses after the effects of the industrial revolution that if all the country concluded this experiment on my back doorstep.........

Portzy.

 

[nickmann]

Thats why you are an Engineer?, and I am a Gas Man . Yep, youre right, I was going back to my carburetter days. Must get an industrial freezer then

Portzy.

Engineer? Get your coat - you've pulled!

Thinking about carbs I reckon they should self-adjust the mixture for density - as a denser fuel might get pulled out thru the jet more slowly. I am on very sketchy ground here and guessing wildy.

I do remember that when I was in the Alps on a bike with open loop mapping I had an issue with an over-rich mixture (it was set by me to be marginally rich at sea-level and got a lot worse at altitude) and another on a carbed bike had no mixture bother aside from the obvious and expected power loss.

 

[portzy]

Engineer? Get your coat - you've pulled!

Thinking about carbs I reckon they should self-adjust the mixture for density - as a denser fuel might get pulled out thru the jet more slowly. I am on very sketchy ground here and guessing wildy.

I do remember that when I was in the Alps on a bike with open loop mapping I had an issue with an over-rich mixture (it was set by me to be marginally rich at sea-level and got a lot worse at altitude) and another on a carbed bike had no mixture bother aside from the obvious and expected power loss.

Sketchy ground here as well but, as I understand it, they dont self adjust for changes in fuel density, neither do injection systems iirc, rather its air density that is the factor taken into account, or rather not taken into account as I dont know of any aneroid? device on a car. Somebody will correct me on that one I guess. So, it must be a 'take' on the exhaust gasses that tell the ECU what to do.

When I was an Aviator we used to have to lean the enigine mixtures manually as we climbed because of the less dense air causing and over rich-mxture. The only problem was coming back down again. If you forgot to richen up the engines they used to stop on you because you were now running too lean. You only forgot once though

Portzy.