I would like to get an idea of what sort of consumption we can expect when we are on the road, and given that the rig is a constant what factors affect consumption and by how much.

We will be towing a 21ft van with an al up weight just under 3 ton, we will be running with a GCM around 6.1 ton. I believe on good roads 100kph will be very tempting, but uderstand that we will get better consumption at 90kph, but how much better.

I also believe there coud be advantage in fitting a roof nounted wind deflector has anyone tried one?

I woud love to hear about other experience, what works for you, what didnt?

B-T wrote:

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Anywhere between 17 to 21 l/100km

John

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 Agree with John,,, in the ballpark here,,, we are 6.5t all up,,,   4.2litre turbo Cruiser Ute. For us over 90kph (usually never under tow) kills the economy.

Drive to RPM that suits fuel burn and good torque. You should be able to get the graphs from manuafacturers books or on line.

Baz421 wrote:

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B-T wrote:

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Anywhere between 17 to 21 l/100km

John

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 Agree with John,,, in the ballpark here,,, we are 6.5t all up,,,   4.2litre turbo Cruiser Ute. For us over 90kph (usually never under tow) kills the economy.

Drive to RPM that suits fuel burn and good torque. You should be able to get the graphs from manuafacturers books or on line.

 

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 Found a UK site that says 600nm of torque @ 2000RPM,,,, so max torque is available at 2000RPM so that's a starting point.

Rest is hard to find on line

Ah found a torque graph at last,,, must be a big secret  for Landy guys ehhhhhhhhh.   See attached graphs.

Use the yellow line for original specs, and the light blue is the increase from chipping the engine.

So you see the max torque is fairly level across about 2000-2200RPM (same as my Tojo) and falls away after 2300 al be it slowly.

So I would drive in the 2000-2200 rev range where possible for max economy (without the benefit of a fuel consumption graph)

Cheers Baz

Thanks Guys, what you are telling me confirms what I was seeing people hinting at on other threads:

1. Fuel consumption with a full size van behind a large high torque vehicle will be up to 100% higher than the same vehicle not towing.

2. Fuel consumption is heavily impacted by speed induced wind drag, and dropping the speed from 100 to 90 appears to make a big difference.

My disco is on its second tank of fuel, and achieved 11.3l/100km on the first mainly city work. When I get it on te highway it averages about 8.1l at 100kph, and sits at about 1420rpm. The motor certainly feels strong from about 1600rpm, and that matches the graph (thanks for finding the graph Barry).

Given the above I expect I will be well advised to use manual mode, and tow in sixth (8 speed box) to get the motor up into a working range under 100kph. I do not have the van yet, but it feels as if I leave it in auto it will ty to tow in eighth.

Thanks for your advice guys.

17kms per ltr is the best i have acheived towing our 23ft sterling keeping the rpm in the 2000 range and keeping to 90kph towing with a patrol 4.2 turbo and contrary to popular belief its fine towing in fifth gear (the fifth gear problem being rectified in 2000) but i always downshift to fourth on inclines to keep rpm around 2000

Neil