MIC’S MEMOS
What’s better, petrol or diesel?
Many well-travelled tourists will tell you that there is arguably more to see within our borders than one could possibly hope to see within a lifetime. I would certainly agree with this sentiment. However, it is nice to venture across our borders every now and then and explore what lies beyond. So during the December holidays, I decided to take my family to Namibia and also take the opportunity to catch up with our distributor in Walvis Bay.
Too much is never enough
I’ve done a fair amount of offroading, but strangely enough I’ve had few dune driving opportunities over the years. Needless to say, I really looked forward to this trip. With permit in hand, I received some much needed instruction from Dirk Bosman at Namib Offroad Centre. Other than gear selection and the correct tyre pressure, the most important piece of advice that I got from Dirk was this: Rather do it over, than overdo it in the dunes. Especially in an FJ Cruiser like I was driving. Third gear, low range, with all traction aids off turns this mild tourer into a dune demon. The 4-litre V6 petrol motor is a gem and as long as you use the throttle sensibly, it’s easy going in any sand situation. I enjoyed the experience tremendously, even though the loose sand was unfortunately not much to my wife’s liking.
Sand lover
When I spoke to Dirk again afterwards, it became apparent that there were way more large petrol engines in the dunes than diesels. There are several reasons for this. Most notable is the fact that, while dieselengined 4x4s have superior torque (Nm) outputs to their petrol counterparts, they do not have the same power (kW) outputs. Take the new Hilux and Fortuner range as a popular example – the 4.0 V6 petrol develops a whole 175 kW at 5 200 r/min. and 376 Nm at 3 800 r/min. The same V6 petrol engine in the FJ develops a healthy 200 kW at 5 800 r/min. and 380 Nm at 4 400 r/min. The 2.8-litre diesel only develops 130 kW at 3 400 r/min, but a whopping 420-450 Nm between 1400 and 2 600 r/min. It was evident in the dunes that even with all of this torque, the diesel-powered vehicles were not doing as well as the petrol ones.
The road is long
In other situations, however, a diesel is definitely tops. Driving from Gauteng to the Namibian coast is quite a journey. Our FJ had a fully laden roof rack with storage boxes shaped like bricks and was, as a result, not very aerodynamic. The occasional head wind did not help matters very much either. During the journey of about 2 200 km, the FJ struggled to stay in fifth gear and I had to keep it in fourth most of the time. On long uphills, even third gear came into play. I’ve done this same trip in a 3.0 D-4D Fortuner (four speed automatic) with a rooftop tent. The vehicle rarely dropped out of fourth gear, maintaining good momentum up and down hills in its highest gear without ever struggling. The trip was also much more laid back, even at the same open road speed.
The difference explained
I’ve always struggled with the exact concept of the difference between power and torque (A clever guy once told me that power = torque x engine speed. But then he kind of lost me and I turned the wors over. – Jaco). So this trip was a very good practical example of the difference between power (kW) and torque (Nm). The superior kilowatts and high revving ability of a petrol engine get you over the dunes far more readily. But the heaps of low down torque developed by turbodiesels make getting there a lot easier, not to mention easier on the wallet at the fuel pumps.
Rather do it over, than overdo it in the dunes.