Re: Fuel economy of Xplorers

["William Pearce" <ben_issacs@optusnet.com.au>]

    In re fuel usage of diesel engines, the average good diesel engine has a
Specific Fuel Consumption of about 0.27 litres/kW/hr, or 0.2 litres/BHP/hr.
So, if you know the average kW or horse power per hour used in a journey by
any diesel engined vehicle you can get an idea of the possible range of that
vehicle, knowing the tank capacity.  This S.F.C. figure is based on the
Imperial figures of 0.35 pounds weight of fuel / brake horse power/ hour,
just in case anyone wants to check my conversion from Imperial to metric
units.(diesel fuel is about 8 pounds to the Imp. gallon, and engine thermal
efficiency is assumed to be 33%).
                            Regards,
                                                    Bill.

9

"Alex Pout" <alpout@optusnet.com.au> wrote in message
3a168744$0$10197$7f31c96c@news01.syd.optusnet.com.au">news:3a168744$0$10197$7f31c96c@news01.syd.optusnet.com.au...
> I've just had a look at Countrylink's website, they reckon a 1700 litre
tank
> will give an Explorer a 16 000 km range.  Working this out, that comes to
> 10.625 litres/100km, or 9.4km/litre.  Now, my car (a 97 Barina) just
managed
> to get about 550km off a 40 litre tank, ie 7.27 litres/100km or
> 13.75km/litre.  Is Countrylink's claim realistic, or has someone missed a
> decimal point?
>
>
> At first I thought, someone's missed a decimal point, but after thinking
> about it for a while (does it help/hinder if I confess to becoming a
> mechanical engineer, and done a bit of study on engines?) I thought maybe
it
> is realistic.  Of course, given time and enough motivation, then I'd do a
> basic thermodynamic study (ie train moving at Xkm/h has so much kinetic
> energy, engine/drivetrain efficiency probably somewhere around 25-28%, Y
> MJ/tonne of diesel etc), but can someone give me a faster answer?
>
> The points I have are: major reduction in rolling resistance for steel
> wheel/rail interface compared to rubber/tar for car, but my car weighs
about
> 900kg, the (3 car) Xplorer weighs in at 174 tonnes.  Also, my car has a
> smaller frontal area and lower speed (110km/h compared to 145km/h), but it
> uses a petrol rather than a diesel engine.  Finally, I know from
experience
> that most trucks will get from around 5 km/litre for light trucks (small
> rigid ones), to around a litre per kilometre for semis and B-doubles, and
a
> B-double is still only around a 1/3 of the mass of the train.
>
> If this is the efficiency of the train (and extending the situation to
> freight), then why doesn't rail freight have so much lower rates than road
> that there is no such thing as road transport??
>
> TIA
>
> --
> Al Pout
>
> No matter where you go, there you are.
>
> alpout@optusnet.com.au
> ICQ 81175245
>
>
>