I don’t understand

[Mike Nel]

Hear me out. Remember. I build leg and arms, not engines


Ok. Take my 200 Cruiser. One thing I do not understand is Diesel Consumption. Almost 20K km’s on the clock, 16K km’s were done towing our 1.5 Ton Bush Lapa Ratel.

So what do I not understand?

Normal driving, without BL. Doing 120km’s per hour. Revvs are 1800 RPM. Consumption = 8km per liter

Towing, doing 120km’s per hour, revvs 2000 RPM, Consumption = 5.3 Km’ per liter.

So my question is this. The Cruiser’s revvs are basically the same at the same speed. According to me not really much more stressed ( just looking at revvs), towing vs not towing.

So why the big difference in consumption? How does the vehicle differentiate between towing and not towing? Again. I am just looking at revvs and the green Eco light on the instrument cluster

[KurtG]

The engine is using more fuel to keep the revs the same.

Is this thread for real?

[ThysleRoux]

1. The revs being 200 more when towing, means it is either in a lower gear or the torque converter is not locking up when towing.
2. Moving [x] kg at 120 km/h requires [y] amount of energy Moving [x+1000 kg + additional drag caused by the trailer ] requires [y+e] amount of energy.

[Mad Manny]

Simple.
You use greater throttle openings to keep the same speed at the same revs.

[Mad Manny]

What is strange is that the LC200 is big & powerful yet the consumption jump from 8km/l(12.5) to 4.5km/l(22.0) is massive.

With Fearless I jump from 8.62km/l(11.6) normally to only 7.52km/l(13.3)

I suspect that Bush Lapa weighs a lot more than 1.5 tons & has much more wind resistance than my Conqueror Conquest.

[ThysleRoux]

MalMan, the revs do not stay the same and do diesels not supposedly only inject as much fuel as needed?

[Mad Manny]

Yes, I don't understand the 10%+ rise in revs.
Wonder if the first (not towing) is 6th & the 2nd (towing) is 5th?

[ThysleRoux]

Either that or the torque converter slipping

[Hedgehog]

MalMan, the revs do not stay the same and do diesels not supposedly only inject as much fuel as needed?

Diesels inject more fuel if you put in more air, so larger throttle openings, gives more air, thus more fuel, thats why some diesels smoke a bit under acceleration

[grips]

Torque converter lockup. Gearbox ECU feed in more slip under load. More load will result in a kick down to lower ratio. The auto box on my 4.0l Ford Ranger did the same.

[BushWacker]

... I seem to recall that the wind resistance
on a moving vehicle is prop to the
3rd power (!) of the cross-sectional area ....

... so a farari should have far less resistance
than a defender at same speed
(but its just gurgling above idle ...!)

the weight and rolling friction etc
of towed vehicles obviously also
relevant ...
varying wrt constant / changing ‘speed’(v)

[ThysleRoux]

Andrew, I agree that more fuel is introduced with bigger accelerator openings, but air input does not affect diesel input. Any engine requires more fuel to do more work, but diesels are supposed to be more precise in the fuel volume control, accelerator position should not affect it as much as in petrol engines.

I still think the OP's issue is gearbox related - probably by design by not allowing lock-up of the torque converter or by not running in top gear. This is the only explanation for the increase in RPM.

@ Bushwacker - exactly the point in my "formula" posted earlier:

Moving [x] kg at 120 km/h requires [y] amount of energy Moving [x+1000 kg + additional drag caused by the trailer ] requires [y+e] amount of energy.

[BushWacker]

... an interesting aspect is that a LC
has big frontal area
whilst a BLapa is low frontal area under tow ...
... then it becomes relevent
how the air stream over the LC
... into face of BLapa or over and past it ???

... think of the function of those air shrouds
the big trucks have over the cab (‘horse’)...

... maybe OP can improve aerodynamics
(not just by cruising at slower speed!!!)

[Mike Nel]

I am more confused than ever

[Flipside]

Hear me out. Remember. I build leg and arms, not engines


Ok. Take my 200 Cruiser. One thing I do not understand is Diesel Consumption. Almost 20K km’s on the clock, 16K km’s were done towing our 1.5 Ton Bush Lapa Ratel.

So what do I not understand?

Normal driving, without BL. Doing 120km’s per hour. Revvs are 1800 RPM. Consumption = 8km per liter

Towing, doing 120km’s per hour, revvs 2000 RPM, Consumption = 5.3 Km’ per liter.

So my question is this. The Cruiser’s revvs are basically the same at the same speed. According to me not really much more stressed ( just looking at revvs), towing vs not towing.

So why the big difference in consumption? How does the vehicle differentiate between towing and not towing? Again. I am just looking at revvs and the green Eco light on the instrument cluster

Have you tried towing on the same route at varying speeds to determine when the deviation from a solo trip on the route is at its worst?

For example, when I travelled in my Jeep, (also a square front) I found that towing at 100-110 km/h gave a much smaller deviation that at 120.
The wind resistance against a rig above a certain speed, becomes much more pronounced.
Obviously this varies for each body shape.