Turbo Glide - Turbo Charging and Diesel Tuning Engineers

turbochargers and diesel fuel injection Australia

As featured in Australian Camper Caravan & Motorhome

Climb Every Mountain

Story and photography by Ian Gerrard

Not many people seem to know it, but the recent advances in turbocharged technology are ideally suited to motorhomes. And with guaranteed power gains- especially at altitude- it's got to be worth it, as long as it's properly installed.

	To many people the motorhome is the perfect recreational vehicle. It offers all the comforts of a caravan but none of the towing problems. Such an opinion is well founded, and the added bonus of 'homes being able to (mostly) hold realistic highway speeds means the impression of them as the ultimate go-anywhere holiday vehicle is a difficult one to shake.
Until, that is, you're travelling at a snail's pace up a hill with the diesel engine straining and clouds of black smoke bellowing out of your exhaust and into the path of the queue of cars banked up behind. The good news is, it doesn't have to be like that, and it's all thanks to that essentially simple but wonderfully effective piece of technology known as a turbocharger.

TURBO BENEFITS Essentially, your average diesel loses three per cent of power for every 1, 000 feet it ascends. So imagine taking your 'home into the likes of the Snowy Mountains- climb 3, 000 feet and you've already lost close to 10 per cent of power. As a result your vehicle will be sluggish and will invariably prove incapable of holding fifth gear. In a non-turbocharged vehicle, because the fuel is delivered by mechanical means via the crankshaft, and because necessity demands the right foot be kept flat to the floor, fuel continues to increase but air volume starts to decrease- hence the black smoke.
But if you could find a way of getting air into the cylinder, you would then burn the fuel that si normally wasted. Which is exactly what a turbocharger does: to force-feeds the engine with pressurised air, thereby allowing more air (and therefore more fuel) to be introduced into the cylinder. And that means more power and higher combustion efficiency.
Such knowledge is hardly new, and, having been largely developed from aeronautics, has been increasingly used in such fields as hour wheel driving. However, it is only in the last couple of years that turbocharging technology has made giant steps forward, making it ideally suited to the likes of motorhomes. That people are only slowly becoming aware of this owes much to the fact that regular turbo installers will not touch motorhomes due to the greatly increased work involved. Fortunately there are exceptions, and a notable one is John Onrust, a man with over twenty-five years experience in turbocharging of all types of vehicles from motorbikes to motorhomes, and the owner of Turbo Glide in Russel Vale, near Wollongong in NSW> It was John that ACCM turned to for the bottom line on turbocharging motorhomes.

SOUND ADVICE "What I always try to stress to people is that if they're going to buy a motorhome, have it turbocharged before the body goes on," said John. "That'll save them time and money."
	Our featured motorhome is a Winnebago Mazda T4000 to which John is fitting a Garrett (his turbo brand of choice) GT25- the most state-of-the-art model available for anything up to five litres in the light commercial/passenger vehicle market.
This three day operation will set the vehicle's owner back around $4,000 (it would have been some $500 less if the body hadn't been on), although prices vary from roughly $3-4,000 depending on the type of vehicle and how much work is likely to be involved. However, given the resulting power gains, it has to be seen as money well spent. It is the essential before-and-after dyno testing at the same regular intervals (50, 70, 90 and 100km/h) that illustrate these impressive increases. Torque gains of 30 per cent are possible, but John tries to keep them at around 20-25 per cent. This is more than enough for the average customer as it means the motorhome will comfortably pick up gear and, moreover, eliminates the possible risk of piston and engine damage that can accompany unrealistically high gains- hence the need for the careful comparisons. While it is possible to buy turbo kits and attempt a DIY installation, such an approach is not recommended. With motorhomes, expert fitting is a must (Turbo Glide, for example, also check exhaust temperatures and, uniquely, emissions to ensure they comply with Australian Standards Particle Count), and even accessories' fitters may get into difficulties with this equipment.

TURBO CARE
	However, as John himself is the first to stress, thouroughness at the installation stage does not absolve the customer from taking care of their new technology: "The secret to turbine life is really the frequency of oil changes. I specify that poeple must change the engine oil at no more than 5,000km intervals. If you do that ( and as long as you use turbo-rated oil), the turbo will outlast the engine".
Fuel is the other critical thing because of the amount of substitute fuels on the Australian market- much of it having been fully adulterated with the likes of turpentine and white spirit. Although cheap diesel is undeniably tempting, it can mean as much as 150km less per tank, which is hardly worth the initial saving. Furthermoe, poor-quality fuel running in a tuerbocharged engine has a nasty habit of causing engine and parts damage. John's advice is to stick to a known quantity. Many people may have heard of watercooled turbochargers (and some magazines have even praised these). However, it should be stressed that these are totally unnecessary in the diesel industry as the exhaust gas temperatures are less than half that of petrol, and any plumbing difficulties would result in irreparable engine damage. You would essentially be building in a problem. As an expert on these matters, John Onrust does not generally install water-cooled turbos, although if he does (due to customer insistence), he only provodes a 12-month, 20,000km warranty instead of his standard two-year, unlimited mileage version. The figures speak for themselves.

THE BOTTOM LINE For an investment of around $4,000 you can indeed turn your motorhome into the ultimate go-anywhere recreational vehicle. And thanks to the power increase the turbo provides, that can include a comfortable trip to the mountains.

The much-trumpeted negative to turbocharging is the possibility of overheating. If the original cooling system is fine and the viscous coupling is working properly, this can generally be traced to the over fuelling of the injection pump, something that shouldn't occur if the unit has been properly fitted.

There can, of course, be few cast-iron guarantees when it comes to such matters, but correct, professional installation is the closest anyone can get. As John says, "Just bolting it on and playing with the injection pump is a recipe for disaster".

Thanks to John Onrust and all at Turbo Glide for supplying the vehicle and technical information for this article.