Case Study: the Khaos Super Turbo Charger (KSTC)
(Why the Khaos gadget does not work)
The KSTC is an air-bleed device, devised in the 1970s by Pablo Planas from the Philippines but recently enjoying a surge of publicity. Air-bleed devices in general are dealt with on
this page, but focussing mainly on their effectiveness (or lack of) on vehicles with catalysts and lambda sensors. While such vehicles are now increasingly common in the Philippines, the main market for KSTC is older, less sophisticated engines typically using carburettors. This page deals specifically with this application.
Theory
Despite some attempts at "mystification", the basic operating principle of the KSTC is clear. It contains a regulating valve and also a spring-loaded (vacuum-operated) valve, which in combination allow more or less air to flow through the device and into the engine. This "KSTC air" does not pass through the carburettor, so it introduces less fuel, and the overall effect is a leaner air/fuel mixture.
(Picture courtesy of Ghosthunter on the
tsikot.com Forum)
The first point to note is that the use of the term "turbo charger" is highly misleading. In the automotive context, a "turbocharger" is very precisely defined as a device that uses the exhaust gas expelled from the engine to spin a turbine, which in turn drives a compressor to
force additional air into the engine under pressure. In this way the pressure in the intake manifold may be "boosted" to typically twice atmospheric pressure, thus approximately doubling the engine's power output. By contrast, air flow through the KSTC is driven purely by manifold vacuum - there is no type of "pressure charging" effect.
The claim by KSTC's manufacturers (referred to simply as "Khaos" here from now on) is that this enleanment of the air/fuel mixture brings the air:fuel ratio close to the stoichiometrically ideally ratio of around 14.5:1, and thus supposedly vastly reduces pollution and gives very big fuel savings. (For example, see
this news story.)
In principle there is some truth in this. It is very well known that excessively rich mixture leads to high emissions of carbon monoxide (CO) and unburnt hydrocarbons (HC), and also high fuel consumption. The theoretically ideal mixture is around 14.5 parts of air to 1 of fuel. This is known as the
stoichiometric ratio. Variations from this are characterised by the term
lambda, where lambda less than 1 means a rich mixture (excess fuel), and lambda greater than 1 means a lean mixture (excess air). If (for example) the engine is run at around lambda 0.9 (10% excess fuel), then the excess fuel is basically wasted; emissions of HC and CO are high, and fuel consumption is around 10% higher than it need be.
Where Khaos's claims depart entirely from reality is with the suggestion that it is common for the mixture to become extremely rich (AFR close to 1; lambda around 0.1) whenever the accelerator pedal is released (ie at idle). The automotive industry has understood the critical importance of fuel mixture control for the best part of a century, and the suggestion that
all, or even
most, vehicles suffer from this fundamental "defect" is highly offensive to those in the automotive industry who have worked hard for many decades to optimise economy and emissions. (That is not to say that there are definitely
no vehicles that behave like this, but they are certainly a tiny minority.)
In fact, even relatively unsophisticated mechanical carburettors do a surprisingly good job of maintaining close to the ideal fuel/air mixture. A fuel/air mixture richer than about 7:1 (lambda = 0.5) simply will not burn, and in practice it is very rare to see mixtures richer than about 12:1 (lambda 0.8) unless the carburettor is faulty or grossly out of adjustment (other than for very brief "transient" effects). So it is exceptionally hard to see how the theoretical fuel economy gains could be more than about 20%, and even that assumes a "worst case" condition before the KSTC is fitted.
Running
leaner than stoichiometric (lambda > 1) can give a further very slight benefit in fuel consumption, but without changes to ignition timing to suit, the maximum benefit is only perhaps five percent. Lean running does in any case also produce a large rise in highly toxic oxides of nitrogen (NOx) emissions (see
here) and may give other additional problems.
Granted, the above analysis indicates that useful savings in fuel consumption and emissions may be obtained by "leaning out" engines currently running excessively rich (say lambda 0.9 or less). So clearly fitting the KSTC can be of benefit? Well, technically yes, but there is a very much cheaper and simpler way to obtain the same benefit. All carburettor systems (and non-catalyst fuel injection systems) contain a "mixture adjustment control", to allow the service mechanic to adjust the air/fuel ratio and compensate for any wear or "drift" in the system. It is usually a standard part of the annual service to read the air/fuel ratio in the exhaust using a gas analyser, and adjust the mixture control at idle until the correct figure (typically lambda 0.95 ... 1.00 (13.8 ... 14.5:1 AFR)) is obtained.
So if you want to improve the fuel economy and emissions of your vehicle, the first and most important thing to do is carry out a routine service, including
adjustment of the mixture control as described above. If the correct mixture cannot be obtained, because the carburettor is worn or faulty, get it repaired - either way will be
much cheaper than having a KSTC fitted, and the engine will then be working the way the manufacturer originally intended. Interestingly, I understand that a "tune-up" is in fact a standard part of the KSTC fitting procedure, which a cynic would suggest means that the tune-up rather than the KSTC is reponsible for most if not all of the apparent benefits.
An additional issue is that the KSTC fundamentally only has a large effect at idle (ie when the driver is not pressing the throttle.) At higher loads and speeds, the proportion of the engine's air passing through the KSTC drops off dramatically and so the amount of enleanment (and hence benefit) also reduces. By contrast, altering the mixture control generally (although not always) affects the mixture at all speeds and loads, and so gives benefits in normal driving as well.
Finally, it is important to realise that there is such a thing as "too lean". The desired lambda at idle is, as mentioned above, typically around 0.95 ... 1.00. Running the engine leaner than this is likely to cause misfires, poor running, high HC emissions and bad "driveability". To some extent this is masked by the KSTC, since the extra air flow tends to increase the idle speed which naturally gives "smoother" running - a higher idle is however also bad since it increases fuel consumption and noise.
As a general rule, returning the engine to the manufacturer's desired state (air/fuel ratio and idle speed) is the best option for optimising fuel consumption, driveability and emissions - rather than simply adding an essentially random amount of additional air, as the KSTC does, which is just as likely to make things worse as better.
One might wonder how the KSTC manages to add the
correct amount of additional air, under
all circumstances, given that it has no feedback of how much air is "missing" (like a modern vehicle with a lambda sensor does) and has a relatively crude adjustment mechanism. Which do you think is more likely to be able to calculate how much air the engine needs - a sophisticated computer controller with sensors for temperature, pressure, engine speed, etc, set up at the factory by skilled engineers over thousands of hours of testing, or a metal tube with a spring?
In fact, vehicles with electronic fuel injection - even relatively simple systems without catalysts or lambda sensors - take things even further. Designers of these systems realised at least 20 years ago that, if the driver lifts off the accelerator pedal above about 2000 rpm (slowing down or driving down a hill), the injectors can be switched off completely. With this "overrun fuel cut-off" the fuel consumption under these conditions is, of course, reduced to zero, and adding additional "KSTC air" cannot make it any less! This highlights the main argument against the KSTC: perhaps it was of genuine benefit on many vehicles in 1973, when it was first developed, but engine technology has advanced enormously since then - which Khaos apparently do not at all acknowledge.
KSTC test results
It is worth commenting on the various test results for the KSTC, and why they prove less than most people think.
Firstly, we have a large amount of
fuel consumption data measured on the road - both "anecdotal" information from users, and semi-scientific studies from various researchers. While superficially persuasive, such data in fact proves nothing at all. The problem is that on-road fuel economy is so greatly affected by other factors (traffic, driving style, weather, type of journey, etc) that any effect of the KSTC is completely masked. See
this page for some general comments on on-road fuel consumption measurement.
Second, there are the measurements of
emissions at idle. It is common to see idle CO concentration drop from (say) 2% to 0.2% when the KSTC is fitted. This is claimed to be "proof" of massively improved combustion, and leads to the claim that the KSTC
"eliminates pollution". In fact this is highly simplistic - it is very well known that CO is strongly affected by air/fuel ratio, and indeed CO is usually used as a
guide to setting the desired AFR. A reduction in CO from 2% to 0.2% just indicates that the mixture is about 5% leaner.
But a reduction from 2% to 0.2% is a good improvement, surely? Well, yes, but this is
only at idle. The total pollution emitted from a vehicle in operation is dominated by the emissions while driving; idle is only a relatively small fraction, even when the vehicle is used in very busy traffic.
And as explained above, the "benefit" from the KSTC falls rapidly away from idle. "Certification" emissions tests, through which all new car designs must pass, measure emissions throughout a simulated drive cycle, since it is well understood that idle emissions are a poor guide to "real world" pollution.
Also, don't forget that this figure is simply a
concentration rather than an absolute amount. If the amount of gas passing through the engine increases, then the
percentage CO will fall even if the total
amount remains constant. Again, "certification" emissions tests always report the total mass of pollutant (typically grammes per kilometer driven) for exactly this reason.
Thirdly, there are a very small number of
"proper", "scientific" drive-cycle tests. This sort of test is exactly what is needed to prove claims as extraordinary as Khaos', and should prove the point one way or another. Two sets of tests have been carried out; by the Automotive Research and Testing Center (Taiwan) and Vipac Engineers & Scientists Ltd (Australia). Both
apparently showed "substantial fuel savings and big drops in carbon monoxide and hydrocarbon levels".
The Taiwan data is widely available on the Internet, and also
here. What does this show? Well, the first and most fundamental point is that this is a
single test, with the KSTC fitted. How can this show a "substantial improvement" in
anything, if there is no "without KSTC" result to compare it with? However, we
can compare the figures for the toxic pollutants (CO, HC, NOx) with values for other vehicles.
Any new car sold in the Philippines since 1st January 2003
must meet the "Euro 1" emissions standards: CO 2.72 g/km, HC + NOx 0.97 g/km. By comparison, the figures for the KSTC-equipped vehicle are CO 7.85 g/km, HC + NOx 4.12 g/km.
So the vehicle fitted with KSTC - a device that supposedly "eliminates pollution" - is three times over the limit for CO, and four times over the limit for HC + NOx!
Critically important here is that vehicles with exhaust catalysts - which Khaos generally imply are inferior to the KSTC -
do easily meet the Euro 1 standard. Indeed, catalysed vehicles have been giving emissions less than a
tenth of those from the KSTC test vehicle, as a matter of absolute routine, for at least the past 15 years.
Suspiciously, nobody outside of Khaos seems to have seen the Australian test results, and despite trying several times to contact
Vipac, I have failed to get confirmation that the tests have even been carried out, let alone that they were as positive as Khaos claim. If I were trying to sell a novel product, and had expensive test data from a reputable company that proved its effectiveness, I would post the results all over the Internet - not keep them secret. What do Khaos have to hide here? If anyone
does manage to find this data, then please
let me know so I can evaluate it properly.
There is a saying in science - "extraordinary claims demand extraordinary evidence". The theory makes it clear that Khaos' claims are highly implausible, therefore very strong test data is needed to prove these claims. Such data simply does not exist, or if it does it has been very well hidden for some astonishing reason. What is needed is some more drive-cycle tests, with several repeats and A-B-A testing, as demanded by the United States
Environmental Protection Agency for assessing fuel "saving" devices. Such testing is not cheap - probably 25 000 US$ - but this is a drop in the ocean compared to the profits Khaos could make by proving their device works. Why, then, are they apparently reluctant to spend the money on such tests?
Effect on engine power
Khaos claim that fitting the KSTC increases engine power. This is however highly implausible - when the throttle is fully opened to obtain full power (accelerator pedal fully pressed), the manifold vacuum is extremely small and so the air flow through the KSTC is essentially zero, and it can have no significant effect on the engine. I have scoured the Web for any reliable test data (dyno testing, acceleration measurements, etc) to demonstrate genuinely improved power, but have so far failed to find any. All we have are anecdotal claims along the lines of "my car feels quicker now" - which proves nothing at all. And don't forget that any actual improvements may, as mentioned before, be due to the "tune-up" rather than the KSTC.
On the other hand, many commentators on various discussion forums have speculated on the risk of engine damage through overheating due to fitting a KSTC. Certainly it is true that the highest exhaust gas temperature occurs at around lambda 1.05, and deliberate enrichment is commonly used on high-performance engines in particular to keep temperatures down at full load. Therefore, if the mixture is made leaner there is a risk of catastrophic engine damage. However, since the air flow through the KSTC (and therefore its effect on air/fuel mixture) falls to essentially zero at wide-open throttle, I doubt this effect could really occur. It does however serve as an indication of why adjusting the engine parameters away from their original design specification can be dangerous.
Rigorous testing of similar devices
The US EPA have been conducting rigorous tests on a number of fuel "saving" products, including air-bleed devices very similar in concept to the KSTC, since the early 1970s. Devices tested on vehicles with relatively simple mechanical carburettors include the
Pollution Master, the
Fuel-Max and the
Landrum Mini-Carb (caution, big PDF files).
No air-bleed device tested by the EPA has given more than a tiny improvement in fuel consumption, and in many cases a large increase in NOx emissions also occured.
Pablo Planas' huge financial offers
I cannot leave this topic without mentioning the vast financial offers alledgedly made to Mr Planas by various large Western automotive companies. Supposedly Planas turned these offers down as he wanted to keep his invention in the Philippines. Now, I have worked for or with some of the biggest car and car part manufacturers in Europe, and in my opinion it is inconceivable that any major company would offer even a hundredth of the figures being talked about for the rights to the KSTC. While a device that genuinely did what Khaos claim probably
would be worth tens of millions of US$, the long history of bogus fuel "saving" products means that any company would demand far more rigorous proof that the device really does work before handing over any money.
Additionally, if the device really did function as claimed, it is likely that a major company would simply copy the idea then use its huge muscle to crush Planas in the courts. The KSTC is after all in principle almost identical to dozens of other air-bleed devices previously marketed, and it is very hard to see how Mr Planas could demonstrate sufficient "inventiveness" for his Patent to hold up. If Planas really was offered 100 million US$, and turned it down, he was very badly advised.
Closing
Some sceptics, reading this, will say "Western vested interests trying to put down a brave Filipino entrepreneur again". Nothing could be further from the truth - I would be very happy to see a Filipino inventor produce some extraordinary new idea that revolutionises the automotive industry, especially if it benefits the whole planet's environment. (And indeed, it must be clear to anyone reading other pages on this site that I am equally critical of many Western fuel "saving" devices.) My real reasons for pointing out the problems with the KSTC are twofold:
1) It seems that, at the very least, it is being "mis-sold", and I don't like to see people spending their hard-earned money on something that doesn't actually do what is claimed
2) The KSTC, for some reason, appears to have the backing of many influential people in the Philippines. The risk is that this diverts attention from
genuine ways to reduce fuel consumption and emissions, which are of course vital. For example, if owners of new cars start removing their catalytic converters and fitting KSTCs instead, the effect on air pollution in Manila could be catastrophic.
