Sluggin' it out with an AXT turbo install.
Words and photography by Mark Allen
Okay, a 4.2L diesel Troopy will never be a standing quarter-mile contender, but hauling around the countryside in anything but top gear tends to wear a little thin after a while. Lugging up hills at 20 kays under the speed limit is tiring; not being able to overtake Grandma until a long, long stretch of downhill straight road is downright frustrating and dangerous. All up, it is a slow home on wheels just waiting to be overtaken - snail bait. Besides, Pat has Otis - complete with 3.8L of V6 - and Ant has just fitted his Denco water-to-air intercooled turbo to his 100 Series, so why should I be the only one left out in the power stakes? As good as Ant's truck now is, my only problem was the need to stick to a lower budget than his set-up. Another extremely important factor for my application is reliability and longevity.
There's no point pumping twice as much power in only to have me sitting on the side of the road in a few thousand kays with a blown engine. I wouldn't be happy and neither would Patski when he has just sent me out on a long-distance outback job expecting the goods to be returned pronto. Unless you're into competition power, the majority of custom 4WDs that clock up big miles would be in the same boat; wanting gains in power - safely and reliably. So, after considering many power upgrade options, I figured on ducking into AXT Turbo's head office in Melbourne to have its Garrett-based turbo system fitted to the 1HZ.
THE LOWDOWN
Daryl Aston - head honcho at AXT - gave me a complete rundown on the turbo packages specifically designed for the 4WD industry. Like many other turbo mobs, AXT utilises a Garrett T3 body as its platform for the 'Cruiser engine (T25 are used for smaller-capacity engines). But that's where the resemblance ends, AXT designs the turbo housing to exactly match each engine type - a one turbo fits all' approach is just not good enough. AXT's design is such that turbo lag is all but eliminated without compromising power and torque figures. It stands by the philosophy that an engine's torque curve should not be altered in any way other than being amplified. That is, increasing the power and torque but not moving it up or down the rev range, which forces the engine to work outside the original design characteristics. The claimed end result is an engine that'll provide a reliable increase in power.
Aside from the turbo itself, AXT utilises a powder-coated cast-alloy ducting to minimise airflow restriction and maximise heat dissipation. A split (two lots of three-cylinder banks) cast-iron intake manifold is used to allow for expansion and contraction, which eliminates the chances of manifold cracking. The Garrett T3 turbo is a water-cooled affair - claimed to be far superior in reliability, as it's able to maintain a constant temperature and won't get so hot to cause damage. The kit includes oil and water teflon braided hoses, which are rated to 4000psi. Following on from the turbo dump pipe is a short mandrel-bent exhaust that matches up with the standard exhaust system.
FACTS AND FIGURES
While every turbo manufacturer will claim final output figures, realistically, a percentage increase from your standard engine is what should be claimed. In the case of a 1HZ, the standard flywheel figures are 96kW@3800rpm and 285Nm@2200rpm. As it's not easy to check this, we measured before-and-after figures at the wheels. Like any 4WD Action test, we attempt to ensure all is above board with our facts and figures. Although AXT does a before-and-after dyno run on its customers' vehicles, we decided to do an independent check in Sydney before the drive to Melbourne and again on our return. Graeme Cooper was to be our backup on this occasion, as he had recently moved shop and installed the latest in Dyno Dynamics dyno gear. Graeme Cooper's pre-turbo figures at the rear wheels saw the Troopy pumping out 41.6kW and 415 tractive Nm (different to plain old Nm) - pretty embarrassing, hey? No wonder Grandma has been blowing me off in her Morris up the hills. Post-turbo figures gave 58.3kW and 580 tractive Nm - a whopping increase of 40.1 percent in power and 39.7 percent in torque. It was little wonder my Troopy felt like its spinnaker was full on the run back to Sydney. On the 1000km return trip, the fuel consumption did raise a little from 14L/100km (pre-turbo) to 15L/100km (post-turbo). With my Troopy loaded with a heap of steel barwork, winch, 33in muddies and wanting to let those newfound horses free, I was pretty happy with that. Towing a camper trailer sees me retuning 17L/100km. Perhaps with a few of the mods I have planned, I'll be able to reduce the fuel consumption to better than pre-turbo figures. Catch next issue to read all about it.
REAL-WORLD TESTING
Real-world driving is as important (if not more so) than dyno figures, and the improvement over all driving conditions is more than pleasing - it's a damn shame I didn't do it 120,000km ago instead of procrastinating about it. With the AXT turbo kit installed, highway cruising is almost as good as Toyota's factory turbo-diesel engine (1HD-FTE electronically controlled, multi-valve unit) and easily maintained legal Highway Number One speeds from Melbourne to Sydney. This was the first time I had spent so much time in the right lane - generally being relegated to the left (or slow) lane - overtaking others with ease. Back-road tripping was a blast, being able to accelerate out of corners like never before - but obviously keeping in mind that a Troopy will never handle like a sports car and muddies were never designed to offer high levels of bitumen grip. 4WDing - both high- and low-range - is now a much easier affair. The Troopy can utilise its newfound torque to stay in high-range more often, and this makes towing camper trailers and caravans much more relaxed.
WHAT WE DIDN'T DO - YET
As part of this turbo fit-up and test, we figured on trying to break a few of the steps up to see how much difference they make - if any. Firstly, AXT did adjust the fuel pump of the Troopy post-turbo fitting, but was asked not to play with injectors, exhaust systems or any other tuning. I know (by feel alone) that the injectors are not working to their maximum - presumably clogged up after 120,000 kays of using our less-than-ideal Australian diesel, so replacing them will (hopefully) give another small increase in power. Upgrading the full exhaust system, giving the 1HZ a full tune and changing air filters will (again, hopefully) make improvements all round. Make sure you grab next month's issue to see how much extra bang for your buck you can expect from all the little bits and pieces.
COSTS AND CONTACTS
The Advanced 4x4 Turbo Systems (AXT) kit for a 1HZ 78 Series Troop Carrier rounded out at $3190 plus $550 fitting. The job can be done in a single day and includes a before-and-after dyno run. Extras, like exhaust upgrades, injector work and any other tuning work can be carried out at the time of the turbo install. For more information on a turbo fit-up for any brand of 4WD, give AXT Turbo's head office a call on (03) 9793 7740. It'll give you all the goss on your particular model and direct you to your closet outlet/fitter Australia-wide. Also have a look at www.axtturbo.com.au. |
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