How can you work out what the fuel consumption is at tickover over
long periods?
Over the next couple of weeks I'm going to be sitting my my car with
the engine and heater running for about 6 hours at a time, anyone know
how much fuel this will use?

It averages 25mpg (petrol) when driving.
It's a 3.2 Jaguar and tickover is about 750rpm i think.

--
Mark.
www.mvp-fine-art.co.uk
www.markvarleyphoto.co.uk
www.mvp-gallery.com
www.4x4info.info
www.beautifulbondage.net
www.facelessladies.com
www.shoot-to-thrill.com
www.bespoke-bondage.com
"nec aspera terrent"



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On or around Wed, 01 Feb 2006 13:22:18 +0000, MVP
enlightened us thusly:

How can you work out what the fuel consumption is at tickover over
long periods?
Over the next couple of weeks I'm going to be sitting my my car with
the engine and heater running for about 6 hours at a time, anyone know
how much fuel this will use?

It averages 25mpg (petrol) when driving.
It's a 3.2 Jaguar and tickover is about 750rpm i think.

you could get an idea by comparing the MPG with the normal figure.

I'd question whether 6 hours at a time at idle is good for it - might be
worth considering a different solution; I assume the idea is you're going to
be parked up for 6 hours sitting in the car?

might be more to the point to fit a fuel-burning heater system like a
webasto or similar, or arrange heating from outside somehow.


Been wondering about things like fuel-burning heaters and the like, and
whether it's worth making one... I imagine the diesel ones are just a small
version of the pressure-jet boiler that we have in the house. Might look
into it.

Anyone who's got one: Do they have a blower for forced air for the flame as
well as a blower to get the heat into the cabin?

is heat-exchange straight to air and blow the air into the cabin better than
heating the engine coolant like the various preheaters do?

--
Austin Shackles. www.ddol-las.net my opinions are just that
"There are three sorts of people in the world - those who can count,
and those who can't" (Anon)

"MVP" wrote in message
...
How can you work out what the fuel consumption is at tickover over
long periods?
Over the next couple of weeks I'm going to be sitting my my car with
the engine and heater running for about 6 hours at a time, anyone know
how much fuel this will use?

It averages 25mpg (petrol) when driving.
It's a 3.2 Jaguar and tickover is about 750rpm i think.

Let's try putting a couple of bounds on it:

If you were driving it very, very gently, you might get 50mpg at a
steady 25 mph. So you'd be using 4 pints per hour. Idling would be
less than that, so let's call that the upper limit.

Pull a number from the air for specific fuel consumption: 0.5lb/bhp-hr.
OK, modern engines should do slightly better, but we're talking idling
here. What shall we call the output to engine ancillaries (alternator,
mainly)? One horsepower? So 0.5 lb/hr, and a gallon of petrol weighs
8lb, so that would make it 1/2 pint/hour. Sounds too low to me.

Let's try a guess as to waste heat: Pretend that great lump of metal,
its radiator, and the heater were an electric heater: it's sitting there
idling. Is it like a 1kW heater? Narrh, far too low. 10kW? Bit high
perhaps? Let's say 50% of the energy in the fuel is doing this heating,
and the rest is going out of the exhaust. Let's guess the calorific
value of the fuel as 45MJ/kg or 12.5kWh/kg, or 45kWh/gallon. So 4
pints/h would give 10 -12kWh as "front end" waste heat, which I said
seemed a bit high. So perhaps 2 pints per hour?

So we've got three guesses: 1/2 pint, which I reckoned sounded much too
low; 2 pints; and 4 pints, which I reckoned was too high. Call it a bit
over a litre an hour, if you must.

I leave others to point out errors, fundamental, thermodynamic, or
arithmetical; and to comment on the effect of idling an engine for 6
hours at a stretch. I'd want to give it periodic blasts at well above
idle, but icba to do any more sums to work out the effect of that.

Sorry about the mixed units, by the way. I prefer
furlong-ton-fortnights, with the unit of power the kW (killerwhale).


--
Kevin Poole
**Use current month and year to reply (e.g. )***
Car Transport by Tiltbed Trailer - based near Derby

On Fri, 3 Feb 2006 08:34:09 -0000, "Autolycus"
wrote:


"MVP" wrote in message
.. .
How can you work out what the fuel consumption is at tickover over
long periods?
Over the next couple of weeks I'm going to be sitting my my car with
the engine and heater running for about 6 hours at a time, anyone know
how much fuel this will use?

It averages 25mpg (petrol) when driving.
It's a 3.2 Jaguar and tickover is about 750rpm i think.

Let's try putting a couple of bounds on it:

If you were driving it very, very gently, you might get 50mpg at a
steady 25 mph. So you'd be using 4 pints per hour. Idling would be
less than that, so let's call that the upper limit.

Pull a number from the air for specific fuel consumption: 0.5lb/bhp-hr.
OK, modern engines should do slightly better, but we're talking idling
here. What shall we call the output to engine ancillaries (alternator,
mainly)? One horsepower? So 0.5 lb/hr, and a gallon of petrol weighs
8lb, so that would make it 1/2 pint/hour. Sounds too low to me.

Let's try a guess as to waste heat: Pretend that great lump of metal,
its radiator, and the heater were an electric heater: it's sitting there
idling. Is it like a 1kW heater? Narrh, far too low. 10kW? Bit high
perhaps? Let's say 50% of the energy in the fuel is doing this heating,
and the rest is going out of the exhaust. Let's guess the calorific
value of the fuel as 45MJ/kg or 12.5kWh/kg, or 45kWh/gallon. So 4
pints/h would give 10 -12kWh as "front end" waste heat, which I said
seemed a bit high. So perhaps 2 pints per hour?

So we've got three guesses: 1/2 pint, which I reckoned sounded much too
low; 2 pints; and 4 pints, which I reckoned was too high. Call it a bit
over a litre an hour, if you must.

I leave others to point out errors, fundamental, thermodynamic, or
arithmetical; and to comment on the effect of idling an engine for 6
hours at a stretch. I'd want to give it periodic blasts at well above
idle, but icba to do any more sums to work out the effect of that.

Sorry about the mixed units, by the way. I prefer
furlong-ton-fortnights, with the unit of power the kW (killerwhale).

Thanks for the numbers which went straight over my head, but i noted a
litre per hour which is a fair ballpark figure.

I worked for a short time doing radio relay when in the army and our
land rovers were ran on tickover for many hours and indeed days at a
time, though they were clearly robust land rover diesel engines so any
negative effects may be not present.

It's my intent to take a sleeping bag and run the engine instead every
few hours to keep the cab up to around 15c.
what odd things i end up doing in this line of work...

thanks again.
--
Mark.
www.mvp-fine-art.co.uk
www.markvarleyphoto.co.uk
www.mvp-gallery.com
www.4x4info.info
www.beautifulbondage.net
www.facelessladies.com
www.shoot-to-thrill.com
www.bespoke-bondage.com
"nec aspera terrent"



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On Thu, 02 Feb 2006 10:20:17 +0000, Austin Shackles
wrote:

On or around Wed, 01 Feb 2006 13:22:18 +0000, MVP
enlightened us thusly:

How can you work out what the fuel consumption is at tickover over
long periods?
Over the next couple of weeks I'm going to be sitting my my car with
the engine and heater running for about 6 hours at a time, anyone know
how much fuel this will use?

It averages 25mpg (petrol) when driving.
It's a 3.2 Jaguar and tickover is about 750rpm i think.

you could get an idea by comparing the MPG with the normal figure.

I'd question whether 6 hours at a time at idle is good for it - might be
worth considering a different solution; I assume the idea is you're going to
be parked up for 6 hours sitting in the car?

might be more to the point to fit a fuel-burning heater system like a
webasto or similar, or arrange heating from outside somehow.

Yep, alot of waiting around in the cold, nor really worth setting up
an alternative source of heat.
Plan is now to take a sleeping bag and run the engine as needed to
warm the place up.

--
Mark.
www.mvp-fine-art.co.uk
www.markvarleyphoto.co.uk
www.mvp-gallery.com
www.4x4info.info
www.beautifulbondage.net
www.facelessladies.com
www.shoot-to-thrill.com
www.bespoke-bondage.com
"nec aspera terrent"



.................................................. ...............
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at http://www.TitanNews.com
-=Every Newsgroup - Anonymous, UNCENSORED, BROADBAND Downloads=-

MVP wrote:
How can you work out what the fuel consumption is at tickover over
long periods?
Over the next couple of weeks I'm going to be sitting my my car with
the engine and heater running for about 6 hours at a time, anyone know
how much fuel this will use?

It averages 25mpg (petrol) when driving.
It's a 3.2 Jaguar and tickover is about 750rpm i think.

--
Mark.
www.mvp-fine-art.co.uk
www.markvarleyphoto.co.uk
www.mvp-gallery.com
www.4x4info.info
www.beautifulbondage.net
www.facelessladies.com
www.shoot-to-thrill.com
www.bespoke-bondage.com
"nec aspera terrent"



.................................................. ..............
Posted via TITANnews - Uncensored Newsgroups Access
at http://www.TitanNews.com
-=Every Newsgroup - Anonymous, UNCENSORED, BROADBAND Downloads=-



mpg at idle is the worst possible, its zero mpg.

On Sun, 05 Feb 2006 12:30:05 GMT, xxxxxl
wrote:

MVP wrote:
How can you work out what the fuel consumption is at tickover over
long periods?
Over the next couple of weeks I'm going to be sitting my my car with
the engine and heater running for about 6 hours at a time, anyone know
how much fuel this will use?

It averages 25mpg (petrol) when driving.
It's a 3.2 Jaguar and tickover is about 750rpm i think.

--
Mark.
www.mvp-fine-art.co.uk
www.markvarleyphoto.co.uk
www.mvp-gallery.com
www.4x4info.info
www.beautifulbondage.net
www.facelessladies.com
www.shoot-to-thrill.com
www.bespoke-bondage.com
"nec aspera terrent"



.................................................. ..............
Posted via TITANnews - Uncensored Newsgroups Access
at http://www.TitanNews.com
-=Every Newsgroup - Anonymous, UNCENSORED, BROADBAND Downloads=-



mpg at idle is the worst possible, its zero mpg.

enter, stage left, a mathematics genius.

--
Mark.
www.mvp-fine-art.co.uk
www.markvarleyphoto.co.uk
www.mvp-gallery.com
www.4x4info.info
www.beautifulbondage.net
www.facelessladies.com
www.shoot-to-thrill.com
www.bespoke-bondage.com
"nec aspera terrent"



.................................................. ...............
Posted via TITANnews - Uncensored Newsgroups Access
at http://www.TitanNews.com
-=Every Newsgroup - Anonymous, UNCENSORED, BROADBAND Downloads=-

On or around Sun, 05 Feb 2006 13:02:52 +0000, MVP
enlightened us thusly:


mpg at idle is the worst possible, its zero mpg.

enter, stage left, a mathematics genius.

hehe.

however, fuel comsumption can equally well be quoted as gph...

MPG is actually only useful as an average. Yer car that does 35 mpg at a
constant 56 mph won't do it a other speeds.

--
Austin Shackles. www.ddol-las.net my opinions are just that
In Touch: Get in touch with yourself by touching yourself.
If somebody is watching, stop touching yourself.
from the Little Book of Complete B***ocks by Alistair Beaton.