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Automotive Myths

Debunking untruths

by Julian Edgar

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This article was first published in 2009.

Automotive myths abound. Some have developed over decades. Others have become myths only as technologies have changed. Still others are brand new myths!

But the common ingredient in all the myths is that they’re wrong...

Myth 1: Changing the Air Filter Improves Performance

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This myth has been fuelled by heavy advertising over a long time. ‘Release that power! Get rid of that restrictive factory air filter! 10 kilowatts there for the taking!’ And so on.

The trouble is, unless the car is very heavily modified – eg 50 per cent more than standard power – then the air filter provides very little restriction to the intake.

In fact, if you measure the full-throttle pressure drops (ie restrictions) through the intake system of a car, you’ll find that the air filter usually makes up only about 10 per cent of the total restriction. That is, 90 per cent of the restriction of the intake is NOT the air filter!

The other thing about changing the factory filter to something non-standard is that you embrace the very real possibility that the filtration (ie the catching of rocks) will be poor. You can be pretty well certain that the factory element will actually work well as a filter!

Don’t waste your time changing the factory filter in a near standard car. Instead, improve the flow into, and out of, the airbox.

Note: good quality factory replacement filters (eg from companies like Ryco) are fine: they’re made to OE standards.

Myth 2: Front-Wheel Drive Cars Don’t Handle

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Bizarrely, this myth has been around for decades. Yet it’s now eons since a front-wheel drive car (the Mini) outright won major motor races and rallies, and since that time, plenty of front-wheel drive cars have out-handled their direct rear-wheel drive opposition.

Let me put the myth differently: if you’re a bad driver, you might find that you can be faster around corners in a rear-wheel drive car than a front-wheel drive. For anyone who is competent, FWD vs RWD is a non argument.

Now you might well argue that some FWD cars don’t handle very well. Of course! That’s just like making the point that some RWD cars don’t handle very well. But it’s another thing altogether to suggest that for ‘real handling’ you need RWD.

If you’re one of the ‘old school’ that deeply believes that RWD is somehow much superior, perhaps get into a good handling FWD and do an advanced driving course so that you can learn how to drive a FWD properly.

Me? I don’t care whether it’s RWD, FWD or AWD. There are lots more important aspects of a car that affect its handling than which wheels are driven.

Myth 3: Timid Driving is Safe

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Many people believe that aggressive drivers are dangerous: they push hard, go too fast, are unforgiving of others’ mistakes, and are discourteous. And I think that’s right – these people are dangerous drivers. But the opposite does not necessarily apply – that timid, hesitant drivers are safe.

Often they are not.

It’s not unusual to see a timid driver waiting to cross a busy main road from a side street. They wait and wait and wait, frustrating those stuck behind them. Furthermore, the drivers on the busy road are puzzled too. Why didn’t the other driver come out when there was sufficient gap? Will they drive out right in front of me? Are they about to come out now? Should I brake in case they do make a last-minute dash for it?

And uncertainty breeds danger.

The same applies at roundabouts, when overtaking on a country road, when joining a freeway, even in car parks. In all cases, aggression is bad – but hesitancy and timidity can also be dangerous.

Myth 4: A Huge Intercooler is a Must-Have

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When I first started writing about turbo car modification, I pleaded for people to fit bigger intercoolers. In those days, some turbo cars didn’t even have a factory intercooler, and of those that did, nearly all were tiny.

Now the wheel has turned full circle. People fit the most enormous intercoolers they can possibly jam into the front of the car, complete with equally huge plumbing.

There’s nothing wrong with that in itself, but it costs a lot and often requires that the car get hacked about to fit the new core and plumbing. For example, on one car, the front intrusion bar (located behind the plastic bumper) is removed to create room for the core – and that’s not a good idea...

The upgrade intercooler has to do two things – flow enough so that it’s not a restriction of more than (say) 2 psi of full boost, and cool the boosted air. The latter’s kind of obvious, but it needs more examination. In a street driven car, you’re on boost very little of the time. So the intercooler is subject to alternating periods of coolness and hotness. The hotness is often only 10 per cent or less of the total time! Therefore, you need only absorb and store that heat to get rid of it when the engine is off-boost.

Short answer: before deciding you need something humungous, measure the intake air temp and boost pressure present after the standard intercooler. Oftentimes, you don’t need to go as big as you first thought.

Myth 5: I Need Back-Pressure

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The idea that an exhaust has to provide a certain amount of back-pressure if best engine performance is to occur is a very strange. In fact, back-pressure will only increase pumping losses, leading to higher fuel consumption and lower performance.

The myth has come about because fitting a large exhaust on some cars has resulted in a decrease in power. But that decrease is nearly always because the engine is no longer appropriately tuned! For example, after being fitted with a big exhaust, MAP-sensed engine management systems may run leaner than optimal. Ignition timing is also likely to be no longer best for performance.

It seems obvious, but if you change the efficiency of an engine – eg by a major exhaust change – the original parameters for which the engine was tuned no longer apply. Therefore, if you want to be assured of getting the best results, you should factor-in an engine management retune at the same time as you get your big exhaust.

Having said that, in 20 years of modifying cars – including turbo and naturally aspirated - I’ve never seen power fall with a big exhaust.

And if you’re still a believer in back-pressure, just put a potato up your exhaust tip and see if performance improves...

Myth 6: Hydrogen is the Automotive Fuel of the Future

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The idea that we’ll one day be living in a ‘hydrogen economy’ where all cars run on hydrogen is simply rubbish.

Whether the hydrogen is used as a fuel to be burnt directly within internal combustion engines, or the hydrogen is used to feed a fuel cell producing electricity to power an electric motor, it doesn’t matter - the same problems apply. So what are they, then?

Firstly, where does this hydrogen come from? You can’t mine it or grow it – instead, it has to be produced by an energy-intensive process from hydrocarbon fuels or other substances like water. Straightaway, you’re behind the eight-ball because of the high amount of energy required to produce the fuel. It’s not like solar panels, or even the batteries used in hybrid or electric cars, where you get an effective ‘energy payback’ period – with hydrogen, it’s just an energy-expensive fuel to produce.

Secondly, distribution is difficult and costly – you need either fixed pipelines or tankers, all operating at extremely low temperatures. And all this infrastructure would need to be constructed.

Finally, because of the pressures they’re required to withstand, automotive hydrogen storage tanks are expensive.

It’s really hard to see any of these problems being overcome, and especially overcome so effectively that alternative technologies are invalidated....

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