I’ve been considering writing this month’s column for some time and, as will be seen, one currently ongoing event makes it quite timely. The column relates to conclusions that are often wrongly drawn for many and varied reasons. The topic almost warrants its own book – but here are some actual examples to show that things may not always be what they seem.

When, in 1970, I switched from research engineer to magazine editor, I found to my surprise that our associated motor magazine’s road tests quoted acceleration figures (for a standing start 400 metres) to two decimal places – (say) 17.34 seconds. Yet those 400 metres were simply paced out each time by one of the road test staff. Checks showed that the ‘400 metres’ were in fact anywhere from 370 to about 430 metres. This introduced timing errors sometimes of more than one second (100 times greater than the implied accuracy of two decimal places). But Ford and Holden protagonists fought over such ‘performance test’ results.

The truth, the whole truth …

Major misconceptions can arise when what is revealed is the truth, but not necessarily the whole truth. This arose a few months back in a matter that related to apparent claims that a certain device could enable one solar module to do the same job as three such modules.

The claim was in fact technically supportable - but not in circumstances reasonably related to local RV usage.

When queried, the manufacturer advised me that the test results, on which the claim was based, had been conducted close to the Arctic Circle in mid-winter. There, during the short daily period of sunshine, the nominally one-hundred watt test module produced less than one watt/hour each day. Utilising the product concerned really did increase this about three times. The claim was thus true, but the reality was that a 100-watt solar module produced less than three-watt/hours a day. (Promotional claims for the product were subsequently changed.)

Still in the solar area, it is quite correctly claimed by a few overseas vendors of MPPT solar regulators that their units enable users to benefit from power otherwise lost when solar modules are run in cold places. The rationale behind this is that polycrystalline and monocrystalline cell voltage increases at low temperatures. MPPT regulators do enable this otherwise lost energy to be captured.

But in most of the promotional literature the vendors claim that gains are achieved once temperatures fall below 25 degrees C. But it’s not 25 degrees C ambient they are talking about. It’s the temperature of the little glass-covered black cells under a hot sun. When these are at 25 degrees C, ambient temperature is more likely to be around 5 degrees C.

So here again the claims are supportable but, with rare exceptions, this particular benefit of the otherwise generally worthwhile MPPT technology is likely to be realised only in very cold places with a bright sun, like Alaska.

Mutual Exclusion

Claims for fuel consumption improvement devices need looking at especially thoroughly. Numbers of such devices have been marketed since the early 1920s with some current examples being not dissimilar from those of eighty years ago.

Often the claims will be something like these:
* Increased power
* Increased torque
* Decreased fuel consumption
* Smoother running

But these claims tend to be mutually exclusive. When designing an engine, the engineers consider the end-product’s most probable range of uses. The result is invariably a series of inter-related compromises felt to best suit most users and most tasks, and provide acceptable engine longevity.

The designer can, with varying degrees of ease, provide (say) more power, or a wider torque range, or less fuel usage etc. But changing any one parameter is usually only possible at the expense of one or more of the others.

Replacement chips are readily available for computer controlled engines. These increase torque and/or power, but usually at the expense of fuel consumption and engine life. Were it possible for there to be a general improvement with no negative effects, it’s odds on the engine designer would have incorporated it in the first place.

Occasionally a major breakthrough in design results in overall gains. By taking advantage of otherwise wasted energy, turbo charging is likely to improve torque, power and fuel economy – although the latter may not be realised if the extra power is exploited. But turbo charging was originally conceived in 1915, was used extensively in ships in the 1930s, and by truck builders from the 1950s onward. Several decades went by before it became available as a retro-fittable ‘performance aid’.

Serendipity Happens

Sometimes however an unexpected and often non-intended effect can prove beneficial. There is anecdotal evidence for example that fitting a well-known after-market device in the inlet manifold of early petrol-engined Toyota Coasters moves the peak of the torque curve to a lower engine speed. This is often claimed to allow the vehicle to climb some hills in a gear higher than previously. But this may not be good for transmissions in marginal condition.

Many of the mechanical fuel savers are intended to provide more homogenous air/fuel mixing – but mainly restrict air intake. Less power is available, so less fuel is consumed. But the same effect can be had for nothing by restricting throttle opening. One engine, that was fitted to both passenger cars and delivery vans, had a large washer in the inlet manifold of the van version to limit power, thereby enhancing fuel economy and longevity. Performance enhancement consisted only of removing the washer – but fuel consumption then soared.

Now You Have it – Now You Don’t

A further issue is that, without sophisticated testing equipment (and a thorough understanding of result-affecting independent variables) fuel consumption is surprisingly difficult to measure within plus or minus 5% - and even that is doing well. Changes in temperature and barometric pressure vary the amount of fuel that can be held by the tank, fuel pumps are not 100% accurate, filling station forecourts are not always level. Even minor changes in driving pattern affect the consumption.

The purchase of a ‘fuel economiser’ may well cause the buyer to become aware of fuel wasting habits and change a poor driving pattern accordingly. In an experiment that I was involved in, half of a test fleet’s drivers were told that their cars had been ‘tuned for economy’. All such drivers subsequently and consistently recorded small but statistically significant reductions. Yet all the cars had in fact retained the standard factory settings.

Finally quite major errors in perception occur despite attempts to prevent them. Here is a current and outstanding example.

Tweedeldee/Tweedeldum

Recent pre-election forecasts had a fair part of the media going ape when one week’s polls showed the difference in popularity between Tweedeldee and Tweedeldum appearing to close by four points in about 50. Tweedeldee’s popularity appeared to go up two points. Tweedeldum’s appeared to go down two points. But hardly a media commentator took the slightest notice of the pollsters’ clear warnings that accuracy was no better than plus or minus 3.5% or so for each. The gains/losses are far more likely than not to be in error: to the extent that the four point difference may well have been only one point - and of little or no significance.

Finally, in all manner of matters, bear in mind social psychologist Leon Festinger’s ‘Theory of Cognitive Dissonance’. Festinger pointed out that people are prone to attempt to reconcile poor-fitting beliefs and actions resulting in self-justifications in often curious ways.

Like – ‘that Lo-Blow filter does so work! I spent $250 on it and I’m no fool’.

The theory also attempts to explain the often strange justifications when major prophecies fail to manifest. For those interested in such stuff, Leon Festinger’s book ‘Theory of Cognitive Dissonance’ is, despite its title, actually readable.

Words by Collyn Rivers, W8054.

In his books and general writings, engineer/author Collyn Rivers often describes the lack of rationale behind long-held but flawed campfire and chatroom mythology, particularly in the field of solar and RV electrics. His best-selling books ‘Motorhome Electrics’ and ‘Solar That Really Works!’ (available directly from the CMCA) describe many such examples.