It is hard to disagree that a suit straight off the rack at Woolies or Edgars is not going to fit as well as one that is made from scratch by a gifted tailor who has first carefully measured you from top to toe and then cut and sewn the cloth accordingly.
But that’s a very expensive route to looking good, and the more practical and affordable approach is to buy the suit off the rack and then get the local tailor to tweak it: a nip here, a tuck there. Or you might be lucky − the suit off the rack might be perfect.
But, then again, the pants from a second suit in a different hue, purchased that selfsame day from the same outlet, might feel ever so slightly tighter around your right thigh, for no apparent reason…
Actually, there’s a very good reason. It’s called manufacturing tolerances; and, as with almost anything, there’s a maximum value and a minimum value that things are made to. You might just have got the pair of pants where the seamstress went a little closer to the limit, and the cut of the material could’ve been towards the lean end of the acceptable scale to start with. The result: a snug fit.
It is this basic theory which defines engine-building. For example, a tight piston-to-bore clearance could result in a better power output, and a smaller variance between the lightest piston and the heaviest one could result in a smoother engine.
The tailored-suit analogy is one that Dastek’s Pieter de Weerdt is fond of using, but he’s not an exponent of blueprinting engine hardware, and his forte is tailoring the engine electronics. When it comes to high-volume production, the latter route is easier and cheaper.
Electronic signals that control duration, volume and start/finish points are important in fuelling an engine, but they require tolerances. Management systems are also built to a budget, and designed to take real-world vagaries into account (fuel quality, operating conditions like ambient temperatures and pressure, and engine condition being just some of them). Their setting also reflects the risk profile of the manufacturer in question.
So, a ‘piggyback’ computer like Dastek’s Unichip takes the place of a tailor’s tape and scissors, to get an engine to deliver more than it is rated at – without doing so much as removing the air filter element. All that is changed are electronic signals, and, by managing and monitoring various settings and parameters, an unchanged level of reliability can be retained.
But this is where consumers find out that not all aftermarket systems are created equal in terms of their intelligence and functionality.
Within reason, more fuel means that a turbodiesel engine will make more power, and 10 to 15 percent power gains are within relatively easy reach. If you want it, though, you can get a third more than stock.
Unlike Dastek’s Unichip, most systems (and there are many) monitor engine load only, and don’t have enough brain-power to look at load relative to engine speed. Impressive maximum power is often achieved, but in combination with high temperatures. This is especially dangerous when cruising fast with – say – a caravan in tow. The Unichip can identify this kind of high-load/high-rpm scenario and compensate accordingly.
Final fettling of the Unichip on a dynamometer also allows it to be tailored – there’s that word again – for the specific engine with which it is partnered. Unichip dealers (Dastek is essentially the wholesaler) are required to do this after installation. On some rival systems, the hardware is plugged into the wiring harness, and off you go.
A cheesy conclusion I know, but Caveat Emptor…
So what's it like to drive?
Our experience with Toyota’s latestgeneration GD (Global Diesel) is fairly limited, but I’ve driven the 2.8 in Hilux and Fortuner guises and I can’t help but be impressed. It is really gutsy and effortless, as you’d expect with 130kW and 450Nm on hand. It is uncannily smooth and quiet, too.
De Weerdt’s development mule for his Unichip upgrade is a Hilux D/C automatic, which Stigworx tested at Gerotek. His team had configured the piggyback to be able to literally plug in and out, so that we could toggle between standard and uprated configurations in minutes – seconds, in fact. More back-to-back than that, you can’t really ask for as a tester.
What is most apparent is the alacrity of the initial response. Even latest-generation turbodiesel+auto combos don’t depart enthusiastically, and there’s a much crisper getaway in the Unichip-equipped Hilux.
Per our faithful VBOX data logger, in stock form, the 2.8GD dispatches the 0-100km/h sprint in a decent enough 13.9 seconds, and just fails to reach 120km/h in a 400-metre dash. By comparison, with the new software controlling things, 100 comes up in just over 11 seconds, and at the 400-metre mark it is doing 129.
But these sprint numbers might not matter much to the kind of people who are looking for cruising power from a vehicle that is laden and/or towing. That’s where the Flexibility numbers in our table make more interesting reading. The 80-120km/h ‘kickdown’ – a measure of the response and acceleration needed when passing a bus or 18-wheeler – drops from about 10 seconds to 7.5 seconds. More importantly, the manoeuvre requires 70 metres less real estate to accomplish…
These are the numbers that prompt owners of a Hilux, Navara or Ranger to look to the aftermarket, but the performance shouldn’t be considered in isolation. There’s more to it than that, especially if you want to enjoy that rocket-like overtaking acceleration year in and year out, without having to have an engine rebuilt or turbocharger replaced in-between.
For more product information, and a list of South African fitment centres, go to www.dastekpower.com
To read the performance test results, get the March edition of SA4x4 magazine