SMOKING VERSUS DRINKING
There are quite a few ways to start a controversial Argument. For example " which rifle is best for our conditions", the same can be said about the Isuzu KB 280- some love em, some hate them! For some time it was probably the most Powerful affordable bakkie, and for some it seemed to last forever, while others seem to struggle in not having any breakageís on this vehicle. It is not because some are better than others; it depends what they are used for. Generally diesels prefer running for long periods of time at constant speeds. While Petrol motors seem to adapt far easier to multiple load conditions and start stop driving- provided they do not spend too much time running cold!
And so started a
article I wrote for some magazine back in the dark ages (early 90ís).
Things have obviously changed a lot and now that I revise this article nearly 20 years later, I do so with a heavy heart, as Eddy has passed away a few years back. The good news is, that I do tune Diesels regularly now J
Electronically controlled Diesels are a breeze to tune. Quite a few like their timing changed for more power or to get the heat out of the combustion chamber. Nearly all can take a bit more Diesel somewhere across the load/rpm range and others like more boost. If you fit a bigger or aftermarket Intercooler to your turbo-diesel, you must change fuelling & boost !
Modern† diesel engines have much smaller displacement to those popular 20 years back. Sadly they all tend to suffer from a lack of bottom end torque. Apart from fitting a smaller turbo there is not much you can do. We can increase fuelling at low RPM for more power, but that results in smokiness. Even the twin-turbo Amarok cannot idle over rocks.
Please discard the article below, as history
has run itís course and I have only left it to be for interest sakes.
Nowadays most diesel engines are designed from the ground-up and being turboís exceed petrol engines power by far- for the same displacement.
With the high price of diesel in Namibia I doubt that a 3L D4d Hilux will pay less at the pump than a 4L petrol. Even if both have been tuned to make similar power figures.
Also a diesel still costs more to maintain in the long run.
But if you got one & want it to be optimised, call me please J
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Diesels have for the past few Years been the Farmers Favourite, but remember the days of old when Petrol powered was the way to go! I do not Touch Diesels, so sadly this Article is Biased, but guys like Eddie at Dieseltech are sure to enlighten you further on those smelly Dirty Monsters. To touch on the past, in the USA we compared my Chevy Dually with a Rat 454 against a Friends Turbodiesel Chevy - both hauled 20 foot Race trailers to the same tracks. The Rat had Donovan heads a Torque cam with Headers and a reprofiled Fuelinjection system, which makes it compare more favourable with the fine-tuned Turbo my Friend had.
In the Mountains of Denver, the Diesel, due to the Turbo would stay with my 454, at the coast though I could motor up grades and accelerate from 100km/h past 120 with no sweat, while the Diesel could hardly get by 85.
On Filling up though I normally got 9 while my Friend got 11 Mpg, but unladen the Diesel could get to 19 while I seldom got better than 10. Consider this an unladen 350 Chevy Truck will get you 20 mpg on the USA Highway.
I can offer a completely reconditioned Chevy V8 for 18 Grand with a warranty; so far no one is offering a Big Diesel for even close to double that, why? Core Engines cost nearly the same so do Hard Parts but when it comes to purchasing Carburettor and Distributor compared to a New Pump with Injectors or Rebuilding said Components- My oh my! Compare the difference in price when purchasing comparative Vehicles, please keep in mind that your 1800 Petrol will probably outperform a 2.4 Diesel while Fuelconsumption on Both can be 10 Km/L and Better. OK modern Diesels like the new Landcruiser and B2500 are Great- but how much do they cost in the long run- compare that with a Fuelinjected 4.5 Petrol Cruiser- do not forget that a Diesel is Injected from the start.
With the price of Diesel Fueleconomy becomes a moot point. I am trying not to compare equal Displacement Motors, but equal in Power.
Reliability- talked to People with Ford F250 powered by Cummins lately? Diesels excel in a lot of things, but I guess not in the Plaasbakkie/ recreational vehicle. I know some will differ on my opinion, but this opinion was formed by discussing these points with people in the Field such as you.
A Diesel has an Injector pump, which makes it only fair to compare it to a Petrol Fuel Injection system in terms of effectiveness. Although a lot of people fear EFI, they tend to be dead reliable and need outside "assistance" to give problems.
A Diesel often has a Turbo engineered to it, get a properly designed Turbo system on your petrol motor and see what happens!
If you inspect Engineparts on a Diesel, you will see that they are far more Heavy Duty than those of a Petrol motor are. This is because a Diesel motor has far more stress on its parts, than its Petrol counterpart.
Combustion is also radically different with the one being Constant Volume, while the other being a constant pressure type (thermodynamically speaking that is).
Diesel motors are usually far lower revving than their Petrol counterparts, which increases efficiency and Longevity. Of course I need to bring in my favourite- the natural gas powered motor. Due to the smoother burning gas there are even less stress factors on the motors internals. Except that it can produce more heat due to gas having more latent energy- but this can be handled quite easily. Fewer emissions will cause far slower oil breakdown and a host of other features make it very appetising. The big drawback is gas storage- this is no problem if you are close to town, but living in the Kalahari it needs a whole new infrastructure to keep you supplied.
The consensus seems to be for a vehicle that runs for 15 minutes and then gets switched of, with this cycle being repeated for most of the day- it should ideally be Petrol powered. If your mind is set on a Diesel, try to only use it for long distance cruising and if you have to use it around Town, only switch it off when intending to stop for a long period of time. Extended idle is also bad due to the low oil pressures associated with that and often insufficient cooling due to the fan and waterpump turning slowly.
As far as Engine upgrades go you have far more chances with a Petrol motor- such as cams, Carbs, EFI, Headers and so forth. There is a Hop up market developing for Turbo Diesels in America- Intercoolers, Recalibrated pumps, Different Injectors, Different Turboís etc. but you better be wealthy to afford this.
For those of you who think I will never set hands on a Diesel, I have a surprise- my personal best pickup of all is still the Dodge Ram with a Cummins B2 Turbo diesel Motor. This thing flat hauls and has Attitude + it is probably the modified Diesel Motor of all time (how does 1000 N.M. torque strike you)!