One of the unheralded changes that has occurred in engines of the last decade is the use of resonant volumes on the intake. You know, those odd blind-ended boxes and tubes that you can see under the bonnet, tee’d into the intake. Sometimes they’re long and thin, other times they’re short and fat. Often they’re in full view but every now and again they’re hidden inside a guard or under a radiator cover plate. So what are these resonant volumes for?

And how do they work?

As the name suggests, they’re part of the ‘tune’ of the intake system. As more commonly understood with exhausts, the opening and closing action of the valves creates a rapid starting and stopping of gasflow in and out of the engine. Each time the inlet valves close, the columns of gas rushing in towards each cylinder are abruptly stopped. This creates a high pressure wave that gets bounced back along the intake runner. When it reaches the beginning of the runner, it’s reflected back towards the intake valves. If the intake runner is of the right length, the reflecting high pressure wave will arrive just as the intake valves are again opening – which will help jam in more air.

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The other day I was in communication with an engineer who works for an Australian car company. He’s also an AutoSpeed reader, and our discussion initially wasn’t about his company, but about a personal matter. Simply, he had read that I’d bought a 1988 Maxima Turbo grey market import and was wondering whether I’d like to buy the Nissan workshop manual for a car which came with a very similar engine. He had the manual but no longer needed it. The answer was that yes, I would like it, and over some subsequent emails some amiable negotiating went on over price.

That sorted, the conversation turned to a car that he was driving – his company’s latest and greatest.

In one email he described – at some length – what a wonderful car it was. He listed many other cars that he had driven and/or owned, commenting how good his company’s product was in this light. Since I have heard this from employees of every car company I have ever had contact with (ie ‘my company’s latest product is fantastic’) I simply raised my eyes heavenwards and sent back an email suggesting that I’d heard it all before, and could he come up with some faults that the car had?

This is an anathema to anyone who works for a car company: the current model is always so perfect that nothing could be better… until the next model comes out, of course. To give the man his due (I think he was genuinely enthusiastic about the product, not just pushing the company line), he responded with a few problems he perceived with the car.

Trouble is, they were relatively trivial…

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there’s plenty of plumbing through which air has to flow before it can become part of the combustion process. Then of course after the burn has happened, the exhaust – again, a long piece of bent pipe – has to be negotiated. The flow through these bends therefore becomes an important part of performance. Sometimes in automotive modification we tend to think that we are inventing something new, but there are plenty of other industries where the flow performance of long pieces of bent tube is critical to the performance outcome.

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Inevitably anyone who works (in paid employment) and also works on their own car (for fun) will spend a lot of time twirling the spanners in the middle of the night. And that means that – again inevitably – they’re going to have invest in some decent lighting. (It always puzzles me when I go into poorly-lit workshops – you can literally see the mechanics feeling around for things that – with decent lighting – would be obvious.)

As with most houses around here, mine is built on stilts and so the de facto workshop is located under the house. It’s dim under there, even in the middle of the day. The lighting that came with the house comprises two double fluorescent battens – for an area of about 60 square metres. Not good. I rigged some Portaflood-style 150W directional incandescent bulbs over my workbench, but the rest of the space remained pretty dark.

So what to do? I was undecided… so did nothing for two-and-a-half years.

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As described in stories that we are running in AutoSpeed, over the last few months I have modified my 1988 Maxima V6 Turbo to have increased boost (and less wastegate creep), an intercooler, cold air intake and cat-back exhaust. Nothing wildly exciting or unique about that lot (although the prices for which the mods were achieved was pretty groundbreaking!), but even so I have noticed a few outcomes I never realised would take place. And that’s despite having in the past owned many modified turbo cars…

The Maxima is instrumented with a fast-response LCD temp probe placed in the intake system just before the throttle body. It’s a device that I have also talked about before, but it’s worthwhile stressing that seeing what is really happening beats all the theories in the world, hands-down. (When you’re reading web discussion groups, watch for the posters who write ‘I measured this’ or ‘The stopwatch showed that’ or ‘Here are the dyno curves’. The number of people who just theorise – often incorrectly – is bloody incredible. A few measurements and you know what is happening!)

The first thing that I noticed is that with the anti-wastegate creep boost control in place, the intake air temp gets higher, sooner. That is, the relatively small intercooler is pushed harder because the temp of the air feeding it is hotter, earlier.

As a turbo compresses air, it inevitably heats it. How hot it gets depends on the efficiency of the compression process – but even if the compressor were 100 per cent efficient, the air would still get much hotter than ambient. In the Maxima’s case – as with any other car running an anti-wastegate creep boost control – boost occurs earlier in the rev range. That’s exactly what you want – more boost sooner. But the corollary of that is that the intercooler load rises, even in normal point-and-squirt driving.

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It’s easy to think that vehicle aerodynamics is an esoteric topic not really relevant to typical modified cars. After all, goes the common refrain, if you’re not driving at 150 km/h, who cares? That viewpoint can be supported by some recent Australian cars which seem to be developed more with styling in mind rather than slipping cleanly through the air – the latest Mitsubishi Magna didn’t see the inside of a wind tunnel and HSV products are now developed without tunnel testing.

However, to take that view would be short-sighted – as car manufacturers chase increasingly better fuel economy, you can be sure that low-drag aero will start making a comeback. Of course, for many manufacturers, aero attention never went away…

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It’s been an exciting weekend.

Genuinely exciting.

I have been testing one of the projects from an electronics book I am doing with Silicon Chip Publications. I’ve been selling work to Silicon Chip, an Australian electronics magazine, for a long time – in fact something like a decade. Over that period I have written many articles about car electronic systems, in addition to covering topics as diverse as electric lighting technologies and washing machines.

But what I have been testing over the weekend is all about modified cars.

It began when about six months ago I had a discussion with the publisher of Silicon Chip, Leo Simpson. He asked: how would I like to come up with all sorts of ideas for electronics projects that could be applied to high performance cars? After I devised the concept, the magazine’s chief electronics designer – an unsung genius called John Clarke – would do the hard work (including building the prototype) and then I’d do the on-car testing. And after we’d got a bunch of projects together, they’d be published in a magazine-style book.

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It’s both a curse and also one of the reasons that so many people read this online magazine: cars stir passions in a way that few other mass-produced consumer goods do. The tactility, history and rewards available in cars inspire people to love and hate, engender loyalties and animosities, cause passion and dogmatism. And the journalists who write about those products can inspire almost equal strengths of view….

But back on the products. There’s one aspect I have always found very hard to understand: the blind loyalty to one manufacturer. Simply, I just don’t get it.

I think that I can empathise as strongly as anyone about the history of a marque: Mercedes Benz, the grandfather of them all and so unswerving in its integrity of research and development; BMW, who nearly went broke and pulled themselves out only by producing a fascinating small car; General Motors, responsible for so much of the technology that we now take for granted.

But that is a world away from believing that all GM products are good. Or that DaimlerChrysler never makes mistakes. In fact, to be honest, these notions of manufacturer infallibility strike me as ludicrous.

So when we recently (well, recently when I am writing this) ran a very critical story about the Nissan 350Z, I was slightly bemused by the nature of the widespread discussions that occurred on forums around the world. (It’s easy for me to see what people are saying: I simply follow our in-house referrers’ list that takes me straight to the discussion.) In that story I’d suggested that the 350Z – basically – handled like crap on bad roads, and that the Holden Special Vehicles Clubsport would be a much sweeter car in the same conditions. (To see the story go to “New Car Test – Nissan 350Z Track”.)

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Each week we get a large number of emails from our readers. The emails range from plaintive requests for technical specifications of cars we’ve never heard of, to specific criticisms and/or corrections of AutoSpeed articles, to suggestions about the editorial approach that we are taking. Many of the emails that we think may be of interest to other readers are published in our weekly Response column, while staffer Michael Knowling also responds directly to every email.

We ‘know’ some of the correspondents – simply because over the years we have received so many emails from them – but most are literally just names on the screen. One name that is familiar – mostly because this reader is lives in Israel, and so it has stuck in my mind – is Avner Bronfield.

A few months ago he wrote to us, saying in part:

I feel that for some times you have shifted the focus of the magazine from DIY stuff and articles on how can one modify his car (which is what drew me to the magazine in the first place), to new car tests, feature cars, new technology articles and product reviews. The products reviews (which can be for product sold in the AutoSpeed shop) can even be thought of as advertisements. I don’t mind you endorsing a product – since I value your judgment, but I do miss the “real” article that could have been published instead (I’m referring to the one about how I could turn my 200SX to a 400 BHP road/rally monster by utilising $50 and common workshop tools). It’s a shame, because the “new” type of article can be found in quite a few magazines, but few magazines if any can do the “old” type like you.

That said, AutoSpeed is still one of the best on my list.

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