Tonights puzzler.... at what point does extra range become a burden?

[tk421]

That's what I was looking for... those sort of numbers (1-2% per 45kg weight) make sense, and what I was driving at.

For example, the guy with 210L of diesel in his 'Cruiser is going to be carrying 155L more than me (so a 3% difference approximately in fuel economy) - at what point does that extra fuel load start to impact his range?

You are over thinking this. It doesn't impact your range negatively - Each litre of fuel always gives you extra range but at diminishing returns. Sticking with the Prado - the single tank altitude 150 has a posted efficiency of 8.5L/100km

Assuming each 100kg reduces efficiency by 0.5L/100km (all other things being equal)

an extra 117 litres diesel (100kg), gives you 9L/100 = 1,307km range
add 235 litres (200KG) = 9.5L/100km = 2,477km
353 Litres (300Kg) = 9.10L/100km = 3,529km
471 litres (400kg) = 10.5L/100km = 4,482km
....
2,118litres (1800Kg) = 17.5L/100km = 12,101km range.
....


Of course its a gross over simplification because in the real world, to carry that extra fuel you need bigger tanks/more tanks/bigger engines etc so the effect increases by more each time. But for the average 4wder the effect is negligible. You are still getting more range by carrying more fuel.

[rossm]

On my recent kimberley trip I twice  topped up my Ranger (which held 70 litres) at Drysdale River, paying about 80c a litre more than Derby or Kununurra.

The Ranger has been moved on and I now have a 150 series Prado  with 150 litres so the  same trip probably wouldn't need a fuel stop so there is a saving there.

But the Prado isn't  as economical so I would use more fuel but pay less per litre for it.

I would need McGirr's formula to work our whether I am ahead.

Saving say $50 when the total fuel bill was about a grand isn't a big issue. Not having to queue at a single pump at a remote location is a convenience thing which can't be given a monetary value.

Like wise having to refuel from a jerrycan. While stopped for a photo at Pentecost River a camper trailer passed  with six jerrycans strapped to the top. That's taking budgeting to the extreme.

[Beachman]

I’m assuming the people who fit long range tanks fit them for a reason and that’s they are planning on doing multiple outback trips.

Yes you would have to notice the extra weight when all tanks are full, but in reality how often would you fill the tanks?  I understand if you have a long trip planned or fuel is cheap you fill them up, but the rest of the time I would assume you only half/quarter fill the tank depending on what travel is planned and how much money is in your wallet.

[Bird]

... with six jerrycans strapped to the top. That's taking budgeting to the extreme.

There was a dude (Polish from memory) whose name escapes me years back on few forums who had a rack made to carry 20 jerrys for his journey to remote WA with a few Prado people... 
People do do it...

[Joff]

There was a dude (Polish from memory) whose name escapes me years back on few forums who had a rack made to carry 20 jerrys for his journey to remote WA with a few Prado people... 
Morons do do it...

fixed 

[shanegtr]

I’m assuming the people who fit long range tanks fit them for a reason and that’s they are planning on doing multiple outback trips.

Yes you would have to notice the extra weight when all tanks are full, but in reality how often would you fill the tanks?  I understand if you have a long trip planned or fuel is cheap you fill them up, but the rest of the time I would assume you only half/quarter fill the tank depending on what travel is planned and how much money is in your wallet.

I fill up completly everytime Im refuelling - bit over 180L everytime. Saves going to the servo more often. 

[Hoyks]

There is an old aviation adage; The only time you have too much fuel is when you are on fire


I used to ride bikes as well as 4x4 touring. On the bike it was a bit of a pain only having 400km range, this could be boosted to 500+ by strapping on a 5L jerry, over and above that the cargo had to be sacrificed and the bike got really heavy, more so when it fell over. Economy was always pretty hopeless, or maybe that was how I rode it .

With the BT50 I can get a bit over 800km out of a tank. If I don't fill it up then I don't go as far and have to fill it up more often. As this is inconvenient I just fill it up, run it until it needs filling again and repeat.
Does it affect my economy to a great degree? Don't know, probably no worse than my 50kg steel bar and roof racks.

There is certainly a point of diminishing returns where hauling more fuel burns more fuel and doesn't get you any further.

When I go away I carry 3 x 20L drums and fill them as required. I would like a long range tank, but can't really justify it. My jerries have been through 3 vehicles now, so I'm getting my monies worth out of them.

If I need fuel, then I buy fuel. I'm not so tight that I sweat on every cent. I don't get the idea of going away, spending $60 on fuel drums so you can fill them at home and haul them 1/2 way across the country just so you can save paying an extra $0.20L in a remote area.

[Pete79]

There is an old aviation adage; The only time you have too much fuel is when you are on fire

That's funny...
I was doing some research on bladders over the weekend. I saw this pic and my first thoughts where something along the lines of your quote!

[rossm]

If I need fuel, then I buy fuel. I'm not so tight that I sweat on every cent. I don't get the idea of going away, spending $60 on fuel drums so you can fill them at home and haul them 1/2 way across the country just so you can save paying an extra $0.20L in a remote area.

I agree ... but beer is a different story. 😀

[Hoyks]

I agree ... but beer is a different story. 😀

Oh, hell yeah!
At $80/carton I rapidly become a resistant consumer.

[tk421]

Was a bit bored today...
Assuming a diesel car with a 59litre tank and an economy of 8.5l/100km and each extra 100kg reduces efficiency by 0.5L/100km:

If you carry double your normal fuel load (118litres or 100Kg - you will travel 77km less than if you filled up the 59 litre tank twice
If you carry 4 times your extra fuel load (235 litres or 200 kg) you will travel 291 km less than if you filled up the single tank 4 times
(again a grossly simplified example because each litre of fuel consumed reduces your weight by 0.85kg so your efficiency improves the further you drive.)

I even graphed it

[listo]

I've got a long range tank in my Triton. I can get anywhere between 12 & 13l per 100km empty on a good run, some times up to 14l (don't ask me, it's got a mind of it's own). All that I know is if I'm lucky to get 1000km out of a tank, I wouldn't be too happy with the extra stops with a standard tank on a long trip.
Would I get another long range tank again? Yes I would. I just won't get the same car again. I don't mind if they're a bit thirstier, as long as they have the goomf to justify it.

[Spada]

with a 60lt tank, I have to fuel up about every day while I'm on holidays, and half plan every leg of the trip around fuel stops. With a 170l tank, I can fill up at my leisure.

worth it......

If I'm on holiday, I don't give a rats nanny about fuel economy................If I have to worry about a penny pinching a couple of bucks worth of petrol, then it aint a holiday.

[doc evil]

If I have to worry about a penny pinching a couple of bucks worth of petrol, then it aint a holiday.

AAANNNNDDDD...............We have a winner....................

[Kangaron]

Agree, something similar like going to a restaurant.
If you look at the prices you shouldn't be there.

[Muckinhell]

A little while ago i remmeber hearing or seeing something to do with airlines stopping large distance flights as in this reference from wikipiedia.

https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft

Very long non-stop flights suffer from the weight penalty of the large quantity of fuel required, limiting the number of available seats to compensate. For such flights, the critical fiscal factor is the quantity of fuel burnt per seat-nautical mile.[9] For these reasons the world's longest commercial flights were cancelled circa 2013. An example is Singapore Air's former New York to Singapore flight, which could carry only 100 passengers (all business class) on the 10,300 mile flight. According to an industry analyst, "It [was] pretty much a fuel tanker in the air.

I guess if you could offset the extra weight with lighter camping gear, taking less food/water on the main road trips etc then it wouldn't have an effect and you could make a saving getting the fuel at more price competitive stops as well, but unless your lucky enough to have car already factory fitted with sub tanks etc its prob not worth it unless like said you are planning some serious remote trips.

[austastar]

Hia,
   The RAAF Mirages could use large drop tanks that extended their range by a fraction.
Most of the external tank's  fuel was burnt getting the load airborne.
Cheers

Sent from my GT-N5110 using Tapatalk

[Joff]

Sounds like it's lucky we don't go outback touring in jet aircraft then.

I'm glad I read this, I was about to buy an old F111 to do the Cape in 

[Cruiser 105Tvan]

Much better to have an airborne refueler.
Take off with all the gear and just fill the aircraft enough to get to the bowser in the sky + 25% for error.
Once at the bowser, fill it all up.

Who said 'pigs can't fly'?

[Joff]

Much better to have an airborne refueler.
Take off with all the gear and just fill the aircraft enough to get to the bowser in the sky + 25% for error.
Once at the bowser, fill it all up.

Who said 'pigs can't fly'?

why didn't i think of that. maybe i will get that F111. they are cheap these days. wonder if i could chop into a dual cab 

[Fizzie]

why didn't i think of that. maybe i will get that F111. they are cheap these days. wonder if i could chop into a dual cab 

Just put a hatch in so you can climb down into the bomb bay & you won't even need to chop it! 

[Jeepers Creepers]

If ya use smaller tanks, thus needing to stop more often, would you not have to factor in the fuel used in visiting more service stations.
The slow down factor, the starting off from scratch factor.

Also, allow for the wear and tear on brakes, tyres and steering, and of course, you then have to factor in a coke and mars bars or worse if the place has a maacas.

Oh hell, who gives a flying rats arse, just drive it like ya stole it.

[Joff]

If ya use smaller tanks, thus needing to stop more often, would you not have to factor in the fuel used in visiting more service stations.
The slow down factor, the starting off from scratch factor.

Also, allow for the wear and tear on brakes, tyres and steering, and of course, you then have to factor in a coke and mars bars or worse if the place has a maacas.

Oh hell, who gives a flying rats arse, just drive it like ya stole it.

What about all the extra bitching from the wife when she has to get out and get her hands dirty more often. 

[Spada]

The slow down factor,

What would you know about that ? 

[IanS]

If ya use smaller tanks, thus needing to stop more often, would you not have to factor in the fuel used in visiting more service stations.
The slow down factor, the starting off from scratch factor.

Also, allow for the wear and tear on brakes, tyres and steering, and of course, you then have to factor in a coke and mars bars or worse if the place has a maacas.

Oh hell, who gives a flying rats arse, just drive it like ya stole it.

But remember that you will burn less fuel getting up to cruise speed as you weigh less.

On a more serious note I have watched this thread with interest and would make the following observations.
IMHO long range tanks are a convenient way of carrying extra fuel but not a very cost efective one, the initial cost of the tank is the killer in my opinion, I had the second tank in a Landcruiser and they were probably the only car that could justify having one as you didn't go very far on a tank full.
If you had the choice of driving around with a couple of 25kg bags of cement in the back of your car or not what would you do? I only filled the back tank if I was going to use it.
If you need the extra capacity for remote area travel you are better off having the extra fuel in separate containers, much easier to keep track of how much you have left and also its not a great idea to have all your eggs in one basket so to speak.
Most modern vehicles have a range of over 500km which means that even a full days travelling will only require 2 fuel stops.
Just my thoughts Ian