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Aero Modification

Re: Trialling a Rear Undertray Wouldn't any type of aerodynamic undertray system only come into effect when the car would be moving at a greater speed than 100km/h? Most spoilers are not really doing anything until your doing greater than 130-140km/h (roughly speaking) so testing an aerodynamic undertray at speeds of 100-105km/h would be pointless. How could you expect any results? What was the point of such a test?

I enjoy your articles but was surprised at this one.

Dayna Jury

New Zealand

It is not true to suggest that aerodynamics affects are relevant only at speeds over 100 km/h. In fact, in some vehicles, aerodynamics become important at speeds over 20 km/h. Regarding the undertray, as we showed in Modifying Under-Car Airflow, Part 2, on some cars an undertray gives clearly measurable improvements at test speeds of ~ 100 km/h.

Evo Manual Shift

Just a quick message to ask whether you tried the "tip shift" / self- shift of the Lancer Evo MR during this review - Mitsubishi Lancer Evolution MR? I drive a Passat TDI with DSG and find that the turbo lag combined with the DSG result in some undrivability, but it can sometimes be overcome by shifting manually.



Yes we tried it, but still found it difficult to keep the engine on boost when driving hard.

Digital Pulse Adjuster

I'm looking for a PWM for the ECU output to the fuel injectors. Your articles on your digital pulse width adjuster don't specifically mention fuel injectors, but do mention solenoids... will it work? Or is it only applicable for a fixed frequency application, as I noticed in Part 2 there is reference to setting a frequency value in the memory.

My MAP sensor sends a digital signal, so an enhancer isn't readily available. I would also like to use your motor controller, but again, there's the digital issue with the MAP driving the controller. Perhaps with a filter or converter on the ECU or PWM output, that could drive the controller?

Thanks for your assistance.

David Clark

United States

The Digital Pulse Adjuster varies in output frequency to match the input. Re the motor speed controller, it is designed for a variable voltage input only. You may be able to achieve that with a filter but we don’t provide individual design advice.

Disappointed in Balance

I read some of your articles and am disappointed in the balance presented, if you don't work for an oil company, you don't have to promote them. re 'solar cars..No' catch up with technology of the 90's, solar panel on house roof - charge battery pack - use battery pack to charge car overnight. solar panels on an average car could recoup during the power used in approx 60Kms of travel. we in Australia have so much sunlight and our best exponents and engineers are going overseas where the world is interested in using less oil.

Bruce Hankin


What you describe is a battery electric car. As covered at Alternative Cars, Part 1 Electric, these are very promising.


Just a small request. When carrying out new car tests on utes of the 2wd manual gearbox variety, how about hooking up a caravan or trailer, and try backing into parking spaces. Most of these vehicles (especially Jap designed) run impossibly low 1st and reverse ratios, making them all but useless as a workhorse. With 4wd of course, one usually gets a two speed transfer case thrown in. If you're keen on doing 50kph in reverse, great, buy one, otherwise get an auto - yuk!!!

Mike Clarke

New Zealand

Almost no press or hire cars have tow bars.

Magnehelic Use

So when you were using the Dwyer Magnehelic Differential Pressure Gauge, did you have a sensor mounted remotely or how did you do that? Obviously you couldn't read the gauge on the highway if it itself were mounted under the bumper? I'd like to get one and do some of the testing that you did...


United States

What sensor? It’s just a mechanical pressure gauge - you run a hose to the area of interest.

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