Palaeontologist Richard Fortey makes the point that the apparent inevitability of the demise of the dinosaurs is a purely retrospective analysis – there was nothing in their evolution that predestined them for death. So to use the word dinosaur to portray outdatedness is to completely misread history.

Sorry Richard, but I can find no better term to express it: the Lexus IS200 is a dinosaur. There may not be a single cataclysmic event that will end its tenure on Earth, but its evolutionary path is finished… if it ever existed.

It’s been a while since I drove an IS200 (see New Car Test – Lexus IS200 Limited Edition) and in the five years since, my memory had dimmed a little. But getting back into the car – this one an auto trans Sports Luxury model – brought it all back. In spades. On nearly all criteria of judgement, this is a pitiful car. Why anyone would be willing to hand over the AUD$57,900 (plus ORC!) is completely beyond me. So, on what criteria, then?

Well, take interior space. All cars have to carry things around – they provide transport of goods and people. The IS200 might have four doors, but the rears may as well be welded shut. In the back there’s barely space for a small child – and no way could any normally-sized adult fit in there. And things aren’t much better up front. I’m average in height but my head was brushing the underside of the sunroof cover… with the seat at its lowest position. With the wide rear-wheel drive transmission tunnel gobbling cabin space, there’s no room for the left driver’s leg and the door is close and its sill high. Nearly any other small car on the road has more interior space – or more that is usable, anyway. Try a Honda Jazz, a Mazda 2, a Barina… the list goes on.

OK, so the space utilisation is a design lesson in how not to do it. What about performance? Ahhh, performance…..well, this car doesn’t have any.

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A few weeks ago I bought a GTR. A long time ago – what today seems a very long time ago – I owned a Nissan Skyline GTR, but this new one is very different. How different? Well, for starters, it has only three wheels. And a maximum power output of about 0.2kW. I haven’t measured it, but I understand most fairly unfit people can furnish about 200 watts continuously….

Yes, that’s right, this GTR is powered by pedals.

So how the hell did I come to buy a pedal tricycle? A return to childhood while in the clutches of early senility, perhaps? Well, it all actually started on a photo-shoot for AutoSpeed. In Sydney and Melbourne and Brisbane and Adelaide we have favourite photo locations; places to which we can take a car to make the photos for AutoSpeed articles. One of the locations is in Knoxfield, a suburb of Melbourne. Over the years we must have photographed a dozen cars there.

And during one of those shoots I’d noticed a nearby factory unit. Along with the name ‘Greenspeed’, it had a sign above the doorway showing what I thought was a recumbent bicycle – the sort where the pedals are way out in front and the seat is close to the ground. Having always been interested in bikes, I put away a casual thought: Must go in there some time. Lots of time passed then I was again in the area – this time with 30 minutes to spare. I parked out the front, knocked on the door and went in. I had no idea what to expect, and so when instead of seeing a bicycle I saw a tricycle, I wasn’t too startled.

From the sign I knew it was all gonna be weird…

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A sea change.

A cathartic experience.

The scales dropping before one’s eyes.

To suddenly see something in such a totally new way that one wonders how one ever saw it before.

Well, maybe the latter’s overstating the case a bit, but still, I’ll never see big, multiple exhausts in the same way again.

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Over the years I have made it abundantly clear I am not a fan of SUVs. Call them what you will – ‘four-wheel drive’ is clearly now a misnomer – but a truck-like vehicle with a high centre of gravity, greater aggressiveness in typical road crash impacts, high profile tyres with poor grip that provide vague steering around centre, lousy aerodynamics, crap interior packaging and the apparently unbreakable habit of being thirsty do not, methinks, make for a good passenger car. As a heavy duty towing machine, sure. As a genuine Outback tourer through the dirt and the dust, fine. But not a vehicle appropriate for dropping kids off at school and doing the weekly, urban shopping run.

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As regular readers will know, my NHW10 hybrid Toyota Prius has been turbo’d and intercooled. To fit in the available space, the turbo – one of the puffers from a twin turbo Subaru Liberty – required that its wastegate mounting system be modified. A spacer ring was used to allow the wastegate actuator to be placed in a different orientation to standard. This ring put a small preload on the wastegate rod, resulting in a minimum on-load boost level of 7 psi. That’s 7 psi, even with the wastegate hose connected directly to the turbo compressor outlet – ie no bleed or aftermarket boost control fitted.

Now that’s generally well and good, but sometimes at high loads, 7 psi can cause a problem. Intermittently – and for only a very short duration – the hybrid control electronics closes the electronic throttle. I assume that this occurs because I have exceeded a preset internal safety trip-point for the engine or electric motors. That implies that if boost can be dropped a little at the top end, the throttle shut-downs are likely to stop. (And in previous short-term testing with lower boost levels, the problem did in fact disappear.)

Since the minimum boost level the wastegate can be set to is 7 psi, dropping boost below that requires bleeding air from the manifold. One easy way of achieving this is to allow the blow-off valve to leak, something which can be achieved by pulse-width modulating the boost/vacuum feed to the valve. Working with the airflow meter signal, the Simple Voltage Switch kit allows this boost drop to be triggered at a preset load. This boost leak doesn’t cause any fuelling problems, because a recirculating blow-off valve is used and the air is returned to the intake after the airflow meter.

Using this approach, I initially dropped peak boost back to 5 psi at loads over about 80 per cent of max, with little discernible difference in performance. Since dropping from 7 psi to 5 psi apparently made little variation in the available top-end power, I then decided as an experiment to allow the blow-off valve to leak all the time. (The aftermarket GFB valve runs a variable preload on its internal spring, making this easy to achieve with some spring adjustment and pulling off the vacuum/boost feed hose.) This resulted in a slow rise in boost to a max of only 4 psi.

Of course, slow rising boost is an anathema in a turbo car – you always want boost to come up as fast as possible. In a normal car, the difference between this and the previous boost-as-fast-as-possible-to-7-psi-and-then-hold-it-at-that-level would be like chalk and cheese. The configuration with the slow-rise-to-4-psi would feel half-dead and power would be clearly way down.

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Why is it that people put so much faith in dyno testing? I have written about this topic before (see Driving Emotion – August 2004) but it needs to be continually shouted from the rooftops. Dynos are bloody useless in so many areas of car modification testing that I don’t know even where to start. But I’ll try.

As I wrote in that previous column, they’re pretty well useless for testing turbo boost controls. Why? Well they:

• Don’t take into account the acceleration rate of each gear – vital because boost overshoot on transients is hugely affected by the rate of engine rpm increase.

• They don’t allow the testing of boost behaviour of full-throttle gearchanges (very few people do full throttle gearshifts on the dyno). Again, it’s in just these conditions that you look for boost overshoots and/or slow increases back to peak boost after each gearchange.

• No one ever does a full-bore launch from a standstill on a dyno. And the speed with which boost can be brought up in these conditions – ie controlling wastegate creep – is a major aspect of good boost control.

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Yesterday I did some serious testing. Well, ‘serious’ as in I set out to specifically test and fine tune the air/fuel ratios in my project car.

Despite frequently writing that you should always have an assistant in the car to read gauges and hold hand controllers and make tuning decisions, I must admit that circumstances often force me to do it all myself, as I am driving. (I am cognizant of the dangers involved in doing this; once many years ago while on-road tuning, I ran straight into the back of a car that had unexpectedly stopped.) So yesterday, for the fine tuning, I did in fact sit in the passenger seat. My lady drove the car and our little boy was in the back.

Despite needing to use full throttle as part of the tuning process, the performance of the car (a turbo hybrid Prius) is so slow that it can all be done on open public roads without breaking the law or posing danger to anyone.

While setting-up this car I have at times run numerous in-car instruments, but on this occasion they were limited to a  MoTeC air/fuel ratio meter running from a tail-pipe mounted probe, an LCD intake air temperature display, a LED indication of factory oxy sensor output, and an LCD hand controller connected to a Digital Fuel Adjuster kit. I also brought along a screwdriver and spanner to allow me to adjust the high and low fuel pressure regulators (this car uses a system that switches out the closed-loop oxy sensors and simultaneously switches in higher fuel pressure). A smaller screwdriver was also carried that could be used to adjust the switch-over point between fuel pressures, a change which is triggered by a Simple Voltage Switch kit monitoring airflow as measured by the airflow meter.

The first step was to check intercooler efficiency. While I had previously measured intake air temps, I’d only done so with the front bumper and number plate off the car. I’d physically felt the temperature of the plumbing after driving the car hard, but hadn’t quantified the numbers. And I must admit, watching the LCD temperature display, I was appalled. Initially, on the long trip down from the hills on which we live, the temp had stayed low – about 10 degrees C above the 20 degree ambient. But then, whenever boost was called upon, the temperature rocketed. Like, it would rise to 20 degrees C above ambient after just a few seconds of boost, and 40 degrees C above ambient after perhaps 10 seconds of boost!

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The stories we ran a few months ago on getting best fuel economy included one on driving techniques (see Savings on Fuel – Part Three). None of the techniques mentioned were startling or new; if you read pretty well any of the books on driving published over the last hundred-odd years, you’ll find mention of being smooth, ‘reading’ the traffic flow, rolling up to halts rather than braking at the last minute, and so on.

And while they might not be new ideas, they’re still certainly quite valid when it comes to getting best fuel economy.

Another characteristic of those habits is that they all fall into the category of ‘good driving’. It doesn’t really matter what vehicle you’re pedalling – whether it’s a huge prime mover or a tiny economy car or a turbocharged rocketship – all will respond favourably to these driving habits… habits which will cause little or no concern to other drivers. In fact, you’re much less likely to have accidents if you drive in these ways.

I kinda took that symbiotic relationship for granted – good driving, low accident rate and better economy – until I was rudely awakened by discussion of an ‘economy’ driving technique that seems custom-designed to infuriate other road users… and simply could never be described as good driving.

Thankfully, it’s currently not a widespread practice, is limited to just one type of car, and is pursued by those who can only be – quite charitably – referred to as tossers.

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Start talking the fuel economy of different petrol engine types and designs and things get complex, fast. Amongst other factors, fuel economy is affected by internal friction, pumping losses, combustion inefficiencies and the air/fuel ratio that is used.

The biggie with internal friction is, literally, how big the engine is. A larger engine has longer internal bits rubbing other bits, and so a 5.7 litre V8 is always going to have poorer fuel consumption that a 2-litre four cylinder. That statement applies when both engines are producing the same low power required for cruising, but may not be the case when the power demand is high – climbing a hill while pulling a trailer, for example. In the latter situation, the smaller engine will have to rev very hard to develop adequate power, and the higher the speed of the engine, the greater the power loss through friction. Because of the high loads to which it is being subjected, the small engine might also move out of closed loop (ie ~14.7:1 air/fuel ratio) to a much richer mixture. So as the power demand increases, the practical on-road fuel consumption may not so clearly favour the smaller engine over the larger engine.

Another way of seeing this is to look at the fuel economy gained from a small engine car that always has to have the ring driven out of it to keep up with traffic. In this situation, the fuel economy is often poorer than the larger engine car that is always just loafing along.

Pumping losses refer to the drag caused on the movement of the pistons on their intake and exhaust strokes. Any restriction on the intake – including, critically, the partly closed throttle – will lower the pressure of the air that fills the cylinder on the intake stroke. Rather like drawing down a syringe that has the needle opening blocked, power is needed to overcome this partial vacuum. On the exhaust stroke, anything that restricts flow out of the cylinder – from a poorly flowing muffler to bad port design – will again require power that’s subtracted from what is available at the flywheel.

Some BMW engines dispense with the throttle – and instead change intake flows by varying valve lift and timing – however the intake pumping losses remain. (Diesel engines, of course have no throttle and so much smaller pumping losses.) A better approach to reducing pumping losses is to adopt the Atkinson or Miller cycles, where the closing of the intake valves is much delayed at lower engine rpm. This poorer intake flow requires the driver to more widely open the throttle for a given power output, so reducing pumping losses. However, the engine also develops less power because its volumetric efficiency is much lower than an engine with conventional valve timing. Atkinson/Miller cycles are therefore used only when there is forced induction at low revs (eg a supercharger as in the Eunos 800M) or power is available from an electric motor (Toyoya Prius and most other current hybrids). 

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