Fuel usage

CODHUNTER · Member

Fuel usage

Peter_n_Margaret · Guru

How fast do you drive?
Cheers,
Peter

LLD · Guru

Just towed my Jurgens J1901 10,500kms with my Ranger. Did an extra 4,000kms in the Ranger. Average for entire trip was 13.0L / 100kms. Generally travel between 90 & 95 kph depending on conditions (raining, windy, hilly, twisty, coarse surface). Had the van tyres at 55psi cold (max recommended is 56psi) and ran 44 / 46 psi in Ranger. Tyre pressures have quite an influence on economy.

Meredith · Senior Member

How much does the van weigh? Real ticketed weight not just the plated weight. A 24 ft van with lots of extras could weigh a LOT, which would partly account for your fuel usage. Also how fast do you drive? Even 10kph difference can make a big difference to fuel usage. Head winds can also make a big difference. Our van is just under 3 ton fully loaded, towing with a 2016 200 Landcruiser, we average about 20 litres per 100km travelling at an average of about 90kph. If we go faster we get less. Our best fuel usage has been down to 16 with a very strong tail wind, has been up to 26 with a really strong head wind.

yobarr · Guru

CODHUNTER wrote:
Hi all,
On our maiden trip up the East Coast, stopping at Agnes Waters. We came up the Newell and then across to Agnes Waters. I have filled up a few times on the way and the fuel usage is 24.4L 100km. My towing rig is a 2006 Landcruiser 100 series with an after market turbo. I am towing a 2012 Elite Atlantic Diamond Series semi offroad 24FT caravan.
I think that I am using to much fuel. Is there anyone out there that has the same problem or is this normal? If there is a fix, I am open to suggestions to correct this. While I am up this way could anyone put me in contact with a diesel motor specialist to talk too. Thanks.

Hi Hans....

As close as I can find,the van TARES at over 3 ton......I found only one of that model that was lighter,at 2980kg. .The figures of 24.4 litres per 100km may seem high (11.5mpg!) ,but that is a big van youre towing!!! .Have you considered a proper tune........on my car the operating temps were lower,and the fuel economy drastically improved after the tune. If ever youre near Brisbane,I can put you in touch with my mechanic for a diagnosis.Cheers

-- Edited by yobarr on Monday 20th of August 2018 07:40:19 PM

-- Edited by yobarr on Monday 20th of August 2018 07:40:51 PM

TheHeaths · Guru

We have a 21 foot StarCraft, weighs in at 2700 kg when we tow, and use a 2006 poverty pack 105 series Landcruiser (Standard) with after market turbo.

I tow at 90 kmh or thereabouts, and when towing we get ~ 20 litres/100 km, and average over a trip, with towing and non towing at about 17.5 litres/100 km. That has been consistent over 40000 kms of towing this van with this vehicle.

Mike Harding · Guru

24.4L sounds high but there are so many variables it's hard to say....

Head wind has a major effect upon the energy required (I think it's a square law?) especially for a 4WD and caravan combination which has all the aerodynamic advantages of a brick.

I couldn't find a web calculator for vehicles but this bicycle calculator demonstrates the point well:

http://bikecalculator.com/what.html

Leave all the other variables at their defaults and just change the "Head Wind" field then note the speed reduction this causes. If you wish you can then increase the "Power" field to see how much extra power is required to bring the speed back to it's original.

eg. default head wind of 0kph - power required = 150W - speed = 28.44kph

Head wind of 20kph - power still at 150W - speed reduced to 17.78kph.

In order to bring the speed back up to 28kph the power needs to be increased to 370W - more than double the original, takes a lot of petrol/diesel to do that!

Edit: You can also enter negative numbers in the "Head wind" field to simulate a tail wind.

-- Edited by Mike Harding on Monday 20th of August 2018 08:03:16 PM

Warren-Pat_01 · Guru

Hi Hans,
As the others have mentioned, many things affect fuel consumption - wind (some how mostly I get either strong head or cross winds), your speed, tyre pressures, load (both in the car & the van), terrain (we can't always choose nice flat roads) & the state of your engine.

There may be recommended tuners in the "Recommendations" tab of the forum, barring that have a look in the Landcruiser Forum or simply ask at a caravan park - I've had some good recommendations from CP managers in the past. You will find that a lot of towns work on the "Word-of-Mouth" system for tradespeople.

I have a Diesel-Gas system (www.dieselgasaustralia.com.au -1800 805 993) on my Patrol which helps immensely with power & economy without stressing the car but at this stage where some stations are not keeping gas anymore, it may not be as viable as it was a few years ago. There is a good DGA man at Echuca (Dan on 03-5482 3799). He has the system on his Toyota ute; cleared up an issue that I had last week. Gas is far cheaper in Victoria (65-75c vs $1 in Qld in most places).

Warren-Pat_01 · Guru

Hi Hans,
I've just had an early morning thought - is your vehicle a 6 cylinder turbo-diesel?

If so, do you know when or if ever, the fuel pump & injectors were (have been) serviced? Like my Patrol, it has a mechanical fuel pump. I used to have my GQ's injectors serviced around 140,000 kms. When I took my current GU in, I was told they had never been done as the original paint was still on the injectors nuts. The car had done nearly 300,000 kms - the fuel pump main shaft was worn (known issue - was told Toyota's have similar problems).

Nissan Patrol (not 3L) injectors can be re-tipped. Injector spray patterns can have a BIG bearing on fuel consumption, power. If you were in Townsville, I'd tell you to go to Dynamic Diesel in Garbutt. They are not expensive but worth their weight in gold!!

Yuglamron · Guru

I drive a MAN based MH weighs about 8.5 Ton. 4.6 Turbo diesel four pot. Quite often drive down to the Snowy from Brisbane. Normally drive around the 100Kph as it seems to like that speed. Roughly takes $650 in fuel. Recently had to tow an empty Gypsy trailer down there. Damn thing at 100 was bouncing two feet into the air in places. Ended up towing at 80 Kph. 95% of the way. It dropped fuel consumption down to $320. Fuel prices were around the same per litre so that 20Kph drop made a heck of a difference. Surprised me it was so much.

Aus-Kiwi · Guru

Yep speed and how you maintain speed on hills does effect fuel consumption big time . Just dropping 10kph makes a heap of difference . My MH 6.5 turbo diesel 8.5m . Head winds .i dropping to 80 kph the fuel consumption improves big time . Thing with turbo engines . They do it so easy . At the expence of fuel usage . Keeping clean air cleaner etc helps .

erad · Guru

As stated above, fuel consumption varies according to the speed you travel. It also depends on headwinds or tailwinds.

Basically, you are towing an object with the aerodynamics of a brick. Power loss due to aerodynamic drag varies according to the cube of the speed. What this means is that if you travel at say 80 km/h, you will create X drag. Increase the speed to 90 km/h, the drag increases by (90/80) cubed ie 1.42 times the 80 km/h drag. Increasing to 100 km/h makes the drag (100/80) cubed ie 1.95 times. Travelling at 110 km/h makes the drag (110/80) cubed ie 2.60 times the 80 km/h value. Now, if you are travelling into headwinds, the drag will increase as well. For example, travelling at 80 km/h into a 30 km/h headwind has the same effect (dragwise) as 110 km/h into still air. Similarly, as tailwind will decrease your fuel consumption. I came across the Nullarbor with a screaming tailwind some time back. The fuel consumption was amazing - less than 15 L/100 km with a LPG Pajero towing a poptop van. I was impressed, but at one stage the winds were reported as being 85 km/h, gusting to over 110 km/h. It was not a comfortable trip, but we did it fairly fast.

Now, aerodynamic drag is not the only factor affecting fuel consumption - you have friction within the tyres (which varies only according to the applied load) and you also have to drag a heavy lump of trailer up and down hills, but for flat running it is the aerodynamic drag which would have the most significant effect on fuel consumption.

mezza56 · Senior Member

hi codhunter towing our 3.2 tonne van with a ranger we got 18 - 20 and now with the 200 series lc we get 20 /100klms , your consumption is definitely a bit too high , maybe call berrima diesel or someone like that and put the question to them .

denmonkey · Senior Member

when I took my van away with a mate who has a front folding camper towed behind his triton, I told him I would be cruising at around the 90km/h with the van behind me.
Whilst he normally drives like a bat out of hell(courier) he said he stick with me and check out if it improved his fuel consumption.

When we parted ways on the return journey, he was down into the 13s per 100km.
He told me over the radio that he normally saw around 20/21 per at his normal speeds.
He was absolutely stoked with the difference.
Mind you, he put his foot down after I left the freeway :)

So if speed can make that much difference with a camper, it can make a big difference with a larger van.
Still, I see around 3-4litres difference between 90 and over 100.

Another mate just came back from an Aus tour with his camper (same sort) behind his 200 cruiser and was seeing over 20s.
He got it remapped and a lock up kit installed as part of his trip and it came down 3 odd litres there.

Neither are the same as your set up but food for thought, none the less.

Cheers Brett