As can be seen from the photos, the supercharger sits on the left hand side of the engine bay and receives its air supply via the vehicles stock air intake system including filter. The compressed air then exits and travels through more stock plumbing to the equally stock intake manifold. Very little in the engine bay is modified and great care has been taken to integrate the supercharger in with existing componentry.
Countless hours were spent planning the supercharger’s belt drive system in particular, with a custom ‘slip over’ pulley now used to drive both the air conditioning unit and the supercharger. Arriving at this method was a long haul that involved everything from rubber dampeners to a reversion to the pre 1995 pulley system. As is well known, the engine in the diesel six 100 Series Cruiser is essentially the HZ 75 engine that has been around right back to the 80 Series. In 1995, Toyota changed their harmonic balancer which added 27mm to its overall length, so simply bolting another pulley on for a supercharger would have put the fan into the radiator !
The custom slip over pulley negates this extra projection, but has been designed such that all other stock pulleys and belts do not move from factory set positions. Much planning also went into the actual operation of the supercharger, particularly when it comes to idling and cruising. Under these conditions, the supercharger will continue to spin, yet the compressed air isn’t being used and so a special throttle body is included to maintain smooth driving and overall efficiency. This throttle body is linked to the vehicle’s throttle mechanism and at idle or part throttle openings, the butterfly ‘restricts’ the air entering the supercharger.
Although the butterfly never fully closes, it does so enough to create a small vacuum which in itself lowers the effective compression ratio and hence produces a smoother idle. The overall smoothness of these refinements was more than evident when driving away from Powerhouse to give the set up a good test run. Mind you, the initial impression was one of sheer deception. On the one hand, the diesel 100 still felt big and heavy, while acceleration, although vastly improved, didn’t induce whiplash. Yet a glance at the speedo suddenly revealed that this big bull was galloping along at 95kmh and yet we were only in a 60 zone. Whooooo boy, steady on !!
When higher speeds were allowed, on the Tonkin Highway, the first thing to be noted was that the tacho needle was sitting on 2,200rpm. Two days previous on the same stretch of road (flat and level) and at the same 100kmh without the supercharger, the tacho had been sitting at 2,900rpm. It’s something I had deliberately wanted to check, after seeing the same, phenomenon in a supercharged Range Rover and hearing about how modern superchargers improved the general operating efficiency of engines. It seems clear that the reduction in engine speed whilst cruising at least, would account for a reduction in fuel consumption. This in turn matches up to other reports I’d heard about superchargers producing fuel economy improvements. *** Many people have emailed 4WD Encounter commenting that the above test drive (claiming a dramatic reduction in engine revs) must be inaccurate. 4WD Encounter would love the opportunity to have this phenomenon demonstrated to us, because our understanding is that the fitting of a supercharger does not effect the gearbox or final drive ratios of a vehicle, therefore the engine must do the same revs if at the same speed and in the same gear.
Perhaps the best way to sum it up is that the engine now produces significantly more torque throughout the entire rev range and therefore doesn’t have to perform so hard in order to produce work effort. And, with a nice fat 407Nm of torque on hand, the Powerhouse supercharger kit sure isn’t short on grunt. This was particularly noticeable while travelling up Kalamunda Road, probably the steepest hill in suburban Perth. Admittedly, we hadn’t taken the vehicle up this incline without the supercharger fitted, yet it was amazing just how much pulling power was on tap.
The 60kmh speed limit was quickly reached with little effort, although the real test came when I deliberately slowed the diesel 100 down to 10kmh on a particularly steep stretch (after checking the traffic behind of course !) and then put the boot into her. Incredibly, she just dug in and worked her way up to the legal 60kmh with little fuss and without the engine screaming its head off trying to create useable power.
There were a couple of occasions when the automatic gear stick was dropped back into 2, but this had no long term benefit and it seems in fact that the engine had lost its ability to generate significant power in the upper reaches of the rev counter. In other words, the Powerhouse supercharger kit is all about low down, useable, practical grunt. The Cruiser will still go to 110kmh with little or no effort (and a wee bit beyond I’d imagine !), but it’s all done without attracting attention and without creating a song and dance. Even so, those with a sporting twist might get a few kicks from this kit and I couldn’t help but wonder that if we were in a manual diesel 100 the fun factor might have come into it even more.
As it stands, the gearing on the automatic diesel that this first kit is attached to was all wrong - although more before the fitting of the supercharger. Im many ways, the supercharger made up for the gears being automatically changed too soon, something that left the stock cruiser ‘bogged’ in the outside lane or wherever as explained above.
But of course, we can hear what you’re all asking - how did she go off the road. To tell the truth we didn’t conduct extensive tests in this department, although several hours were spent playing in some pretty deep sand tracks on the outskirts of Perth. Quite frankly, the sheer low down torque is such a joy in the deep stuff, both with the low range engaged and disengaged. Equally, both with the all wheel drive button on the centre console switched on and off, the diesel 100 just ploughed through regardless.
This is undoubtedly where those traditional diesel customers will rejoice. The ruggedness and economy of the beloved diesel can now be matched to the grunt needed for towing that equipment up a 1:2 incline after heavy rains have turned the surface into a quagmire. Or, you can now take the shortcut through that deep boggy sand when it’s time to take some feed out to your livestock. Yet the Powerhouse supercharger kit now opens up the Series 100 diesel landcruiser to a whole new suburban market.
Admittedly, those V8 customers probably won’t be interested, nor perhaps the petrol six Landcruiser buyer. Yet for those to whom fuel economy is important, the diesel 100 with a supercharger kit is a viable option for the city. Those dashes between traffic lights are now less hassle and you don’t have to sit behind learner drivers, buses and taxis for fear of becoming trapped in the outside lane. (c) Rick McDowell 1999
