Offroad-Express

My understanding of the practicality of diesels in the larger applications, i.e. locomotives, ships etc , is due to the torque generated and the ability to use relatively un-refined fuel in the large volumes required. Huge petrol engines are noticeably absent from these operations.
I know the couriers like diesel for all their stop-start running and they dont turn the engines off .

I would consider a diesel but am more likely to find what I want in a 1.6 to 2l petrol with injection and a good engine management system. These are just as likely to yield the sort of economy I require. And again I shall state the primary use will be as a vehicle for travel with the odd bit of off-road at the end.

I appreciate the replies and will spend some time looking at all the options.

prespec wrote:My understanding of the practicality of diesels in the larger applications, i.e. locomotives, ships etc , is due to the torque generated and the ability to use relatively un-refined fuel in the large volumes required. Huge petrol engines are noticeably absent from these operations.
I know the couriers like diesel for all their stop-start running and they dont turn the engines off .

I would consider a diesel but am more likely to find what I want in a 1.6 to 2l petrol with injection and a good engine management system. These are just as likely to yield the sort of economy I require. And again I shall state the primary use will be as a vehicle for travel with the odd bit of off-road at the end.

I appreciate the replies and will spend some time looking at all the options.

People often think there is a big overlap between diesels and petrols for fuel economy. But there's not.

The best petrol engines don't make 30% efficient, but the best diesel engines (like VW's 1.9 TDI) make 42%.
But that's at the best operating point. A diesel has a broad efficiency curve, changes in speed and load don't change fuel consumption much. A big diesel and a small diesel doing the same job can get similar fuel consumption.
But a petrol's best efficiency point is a tiny island which is very easy to miss. Getting off it with changes in speed and load the efficiency plummets in every direction. This is exactly what happens in offroad and city driving and why diesels easily get double the fuel economy in these conditions.

I have two very different vehicles, a japanese 2wd station wagon with a 1.8L petrol and a rangerover with a 3.9L turbo diesel.
The wagon pushes less than half the air and weighs less than half of the rangerover. It gets 12km/l, the rangerover averages 10km/l.

how about something like this: http://www.trademe.co.nz/Trade-Me-Motors/Cars/Isuzu/auction-135956862.htm?
compact, petrol. i've had a diesel one and was very nice to drive on the road, handled great. and nice and cheap so more money to spend on mods and tyres

I am going to look seriously at the diesels now.

prespec wrote:I am going to look seriously at the diesels now.

Wise choice.
I am not going to push any particular brand, except the diesel

Economy? Went from here (Wanganui) to Pureroa, played all day, mostly 4wd, came home. well under 60L fuel.
I go to WTN and NP frequently. Fill HERE, go WTN home and on up to NP in one hit. still less than 60L Fuel.
this equates to around 11KPL (Multiply by 2.82 to convert to MPG for us old farts)
Was in HAM, put Wopass' Missile on a trailer, towed it to Thompson's track, played all day, many times stuck.... econonmy plummeted to 25MPG or AROUND 8.5kpl. DAMN!!!

Road use? 50mm body lift HAS changed the characterisitics a wee bit. still handles ok. cruises well at 120KPH if Siwsie is not looking otherwise is nice at 100 KPH when she is. If she is asleep, I generaly wake her up when we are rocking along at 150KPH.

Radar detector HAS saved some of my fat bacon from time to time.

Odly enough, I cannot find the most econonmic speed. returns the same mileage regardless of speed, Load DOES change things by a wee bit, but not outrageously so.
HUGE engine life.

Thems the positives.
negatives are.

MUST do servicing regularly to prolong engine life. Expensive service,
Fuel stinks burnt and unburnt.
Fuel is greasy and does not evaporate away.
Not as easy as petrol engine to "tweak". Limited to what the backyarder can do.

Bloody road tax.
bastards.
LYING batstards.

Slightly off the topic, sorry.

When petrol was $1.00 per litre, the lying bastards fixed the price of D at $0.50 saying that the diff would remain at HALF THE PRICE OF PETROL.
that situation obtained until the first price hike and all of a sudden the wording was changed to say that the DIFFERENCE between D and P would be fifty cents.
Lying bastards.
D SHOULD now be climbing up to 75 cents per litre.
NOT 126CPL

Moriarty wrote:Odly enough, I cannot find the most econonmic speed. returns the same mileage regardless of speed, Load DOES change things by a wee bit, but not outrageously so.
HUGE engine life.

I too have trouble driving to save fuel. I've tried babying it, I've tried thrashing it over the same roads repeatedly. The difference in fuel economy is within the margin of error.
On my vehicle I put it down to this, run it harder, it creates more boost which increases efficiency.
Baby it, you run less boost, which gives less dynamic compression and lower efficiency.

I've come to the conclusion that to save more fuel on a diesel you need a fuel consumption meter to give some timely feedback.

Moriarty wrote:negatives are.

MUST do servicing regularly to prolong engine life. Expensive service,

I keep hearing this, but I don't see any basis for it. Below is a link for a maintenance manual for the Isuzu NPR fitted with the 4JB1TC engine (2.8 diesel used in bighorns etc). With the worst oil grade they recommend 10,000km oil and filter changes. With better oil they recommend up to 15,000km service intervals. 5,000km is only listed as the extreme service oil change (dusty conditions etc).
http://foto.afn.kz/x/Elf/LGGEN-WE-0001EU.pdf

I change my diesel oil at 10,000km (when I remember), my petrol shopping basket gets 10,000km changes too. The people who advocate 5,000km oil changes seem to be the ones selling the oil.

I have learned some pretty interesting stuff here chaps! Diesels seem to be far less sensitive to operating conditions regards consumption.
I am not really afraid of the maintenance as I tend to look after my wagons anyway....it's cheaper in the long run .

Now the next thing is affording something decent and I may have to wait a while as I'm working the first half of this year to keep beneficiaries in the style to which they are accustomed and paying ACC levies and a welter of other things.............. I wonder If Helen would mind if I used the GST money??......

Kiwibacon wrote:I keep hearing this, but I don't see any basis for it. Below is a link for a maintenance manual for the Isuzu NPR fitted with the 4JB1TC engine (2.8 diesel used in bighorns etc). With the worst oil grade they recommend 10,000km oil and filter changes. With better oil they recommend up to 15,000km service intervals. 5,000km is only listed as the extreme service oil change (dusty conditions etc).
http://foto.afn.kz/x/Elf/LGGEN-WE-0001EU.pdf

I change my diesel oil at 10,000km (when I remember), my petrol shopping basket gets 10,000km changes too. The people who advocate 5,000km oil changes seem to be the ones selling the oil.

Only reason I have been doing the services at the 5000, then 10K perioods is cos I bought it new.
Now, cos I dont drive in very dusty conditions etc, and modern oils are much better than the oils of my youth, and it is now out of warrantee, the period will stretch out to probably 20K. At least until it starts to get old. Maybe 200K, then the period will close again.
So far, wee truck has only done 53K

However, all my other comments are, to me, still valid.

Moriarty wrote:Only reason I have been doing the services at the 5000, then 10K perioods is cos I bought it new.
Now, cos I dont drive in very dusty conditions etc, and modern oils are much better than the oils of my youth, and it is now out of warrantee, the period will stretch out to probably 20K. At least until it starts to get old. Maybe 200K, then the period will close again.
So far, wee truck has only done 53K

However, all my other comments are, to me, still valid.

Severe condition driving also includes towing, frequent short trips and off-road use. The reason short frequent trips is considered severe and calls for more frequent oil change is that the oil and components never get hot enough to evaporate oil and fuel residues. These items contaminate the oil and can cause damage to components (including rusting). There are two solutions, change the oil more frequently or try to drive longer distances every so often. Dusty conditions is just one of the requirements for more frequent oil changes. And before anybody says anything else, no I don't work for an oil company.