General comments

Fuel "saving" gadgets

I have worked in the car industry for over fifteen years, everything from development of novel fuel-efficient engines to mapping of production vehicles. In that time I've seen dozens if not hundreds of supposed "fuel saving devices" advertised. Without exception, I advise you not to buy them! Over and over again, a company starts selling a "miracle" fuel-saving product, which of course is supposedly revolutionary and different to every other product that's been offered in the past; over and over again, the product turns out to be bogus and buyers lose thousands (or even millions) of pounds / dollars. To the best of my knowledge, no "add-on" fuel economy device or product has ever demonstrated worthwhile savings, yet new ones are always being introduced to the market, and uninformed customers are easily taken in by the claims and marketing "hype".

I have no involvement with any of the companies selling these fuel "saving" devices, nor do I get any benefit if people don't buy them. But I'm an honest sort of guy who doesn't like to see people get ripped off, and felt it was time to explain the engineering truth behind the claims. I also object to the fact that some of these devices make emissions worse, which obviously is bad for people's health. Finally, as a car industry engineer, I resent the implication that my colleagues and I are "too stupid" to see the benefits of these fantastic planet-saving gizmos!

I haven't tested every one of them personally, but the physical processes they claim to use are well understood and I have sound practical and theoretical knowledge to go on. Anybody who doubts my views can find a mountain of supporting evidence in the technical literature, based on work by the many thousands of expert reserchers in the field. These are however my own personal views and not those of my employers.

Most "fuel saving devices" fit this pattern:

• About a 10 - 15% claimed fuel saving (gas saving / gas mileage improvement)
• Claimed reduced emissions
• Claimed improved performance
• Cost about £50 (80 US$) (so costs about £5 to make!)

There are many different types, and you can find information on the technical problems with each below. But there are also some general issues with all of them.

Firstly, it's very rare to have any good test data for these devices. Some have been tested scientifically, but often on very old cars, and the data is either suspect, or irrelevant to more modern vehicles.

Measurements showing emissions reduction are nearly always taken from the UK MoT test or something equivalent. This consists of measures of hydrocarbons (HC), carbon monoxide (CO) and carbon dioxide (CO2), and is taken at idle. This completely ignores oxides of nitrogen (NOx), one of the most dangerous pollutants from car engines. It also ignores the fact that the emissions while driving are very different to the emissions at idle, because of the higher load and speed.

Sometimes with catalysed cars you will see results such as "reduction in hydrocarbons from 10 ppm to 5 ppm - a 50% improvement!". This is an essentially meaningless result, since the accuracy of typical workshop test equipment is only about +/- 5 ppm. In any case, 10 ppm means that only about one part in 5000 of the fuel used in the engine is escaping from the exhaust, so the effect on fuel consumption or overall emissions is pretty marginal.

Performance increases are usually just users reporting "my car feels quicker now" (memorably described by one US commentator as a "butt dyno".) What kind of evidence is that? It's hard for a driver to detect small changes in performance, and measures such as 0 - 60 time are extremely dependant on driving style. There are objective ways to measure car performance, the main ones being in-gear acceleration times and "before and after" rolling road measurements. Companies selling devices that genuinely improve performance (such as "chipping" upgrades) always quote measurements of this sort, and they are not difficult or expensive to do. So when somebody claims a performance increase but doesn't have any data of this sort to back it up, ask yourself why. (Also note that variations of two or three percent on rolling-road tests are not at all unusual, due to such things as changing air temperature, so unless there are several "with" and "without" repeats an apparent improvement of this level is insignificant.)

Fuel consumption is what most people are interested in. Again the claims are almost always based on users reporting fuel consumption improvements, and not any kind of objective measure. The basic problem here is that fuel consumption is extremely sensitive to driving style, type of journey, even the weather. On my own car, I often see variations in excess of +/- 10% from the average fuel consumption. These variations occur both between subsequent refils, and over a longer period of time due to changes in weather and journey type. You can find a lot more information about the dangers of relying on testimonial evidence, including your own personal experiences, here.

Often some users report big improvements while others find no improvement or even a deterioration in fuel consumption. This is not surprising, given the variability you always see. Funnily enough, the companies selling these devices only report the positive results! There is a long history with fuel "saving" devices of glowing customer testimonials followed by scientific tests proving the device has no significant effect.
It's even worse, though, because it's not a blind trial. In drug testing, neither the patient or the doctor is allowed to know if they're getting the real drug or a fake, because it affects the results. When the driver knows they have a fuel-saving device fitted, it's bound to affect driving style. (If you inject a hundred sick people with plain slightly salty water, most of them will report an improvement in their symptoms. That's why we have double-blind trials, control groups and the like - scientific testing, in other words.) With the greatest of respect to people who have tried these things, uncontrolled testing under variable conditions does not constitute proof!

Some people argue that this doesn't matter. If fitting one of these devices apparently improves fuel consumption, does it matter if this is due to a change in driving style rather than an actual technical improvement in how the engine works? (the "pragmatic fallacy"). Personally, I think it does matter, as:

• Some devices (eg air bleeds) may greatly increase toxic emissions
• It distracts attention (and money) from genuine ways to save fuel
• The makers are still effectively lying in their advertising

Another issue with these tests is that you almost never see an A-B-A test. Fit the device, see an improvement in MPG. But to prove the point you must then take it off again and prove the MPG gets worse. Otherwise it could have just been a coincidence, or due to something else changed at the time of fitting.

The "gold standard" for emissions and fuel consumption testing is the emissions drive cycle. This is a standardised profile of speed against time; all new vehicle models are driven over this cycle on a rolling road to provide legal proof of compliance with emissions limits. The European cycle covers about 5 miles and includes both "town" and "country" driving, so is fairly representative of what happens in the real world. The test is run under absolutely controlled conditions, with even the air temperature fixed, and so gives repeatable results. This test - and only this test - is accepted by governments all over the world as proof that a particular car has the emissions and fuel consumption that the maker claims.

When a "fuel saving device" presents results from an emissions drive cycle, then there may be something in it. Any other sort of test data should be taken with a large pinch of salt! Many independent test facilities are certified to carry out this testing, and the process is not difficult or time-consuming. As a fraction of the hundreds of thousands of pounds a year profit made by some makers of fuel "saving" devices, the tests are not even particularly expensive. When someone makes claims that are completely at odds with current scientific and engineering knowledge, surely it is up to them to prove that their claims are true, with proper scientific testing.

The definitive guide to testing fuel "saving" devices is that of the US Environmental Protection Agency The EPA has been testing such devices since the early 1970s - both because of a desire to save fuel, and equally because many such devices actually make emissions worse. The EPA guidelines clearly explain what must be done to properly evaluate a fuel "saving" device, and in particular make it absolutely clear that emissions measurements on the Inspection & Maintenance test (the equivalent to the UK MoT) are of no value in this evaluation. The essential requirements to prove a fuel "saving" device works are:

• rolling-road tests, over standard cold-start cycles such as the FTP75 (US) or ECE+EUDC (Europe)
  
• a test car (preferably two) that is reasonably modern, and in good condition (emissions and economy in line with when it was new)
• at least two tests in "standard" condition, followed by at least two with the device fitted (to assess statistical variability)
• ideally, a final pair of tests with the device removed again (to prove it was the device that made the difference, and not some underlying factor such as components bedding-in)

A device that has test data conforming to these requirements, and where the gain is several times larger than the test-to-test variability, is almost certainly of genuine benefit. Anything less rigorous (old car, no repeat tests, etc) should be treated with some suspicion.

Many American devices claim "We have a CARB number and so it is legal to fit this device". While true, this does not in any way indicate that CARB (California Air Resources Board) certify that the device actually offers the benefits claimed. The CARB number merely indicates that CARB do not believe the device makes emissions worse, and does not indicate anything else. For example, the CARB Executive Order for the Tornado Fuel Saver specifically states: This executive order does not constitute a certification, accreditation, approval, or any other type of endorsement by the Air Resources Board of any claims...concerning anti-pollution benefits or any alleged benefits. Since the vast majority of fuel "saving" devices have no effect at all, either positive or negative, it is unsurprising that they can obtain CARB numbers (and in many cases this is based on "engineering judgement" rather than actual tests). To check if a particular device has a CARB number, visit their database.

People frequently ask why I criticise such devices without having personally tested them. The reason is that I could fit one to my car but it would prove absolutely nothing. Any fuel economy effect would be lost in the variation of normal driving (as discussed here). The emissions tests I could do (basically CO and HC at idle, as measured on the MoT test) would say nothing at all about the effect on overall emissions while driving, and hence environmental impact. Proper performance testing would require multiple rolling-road tests with and without the device, which would be expensive and time-consuming. For these reasons, I also believe the customer testimonials often quoted by makers of such devices to be of little value.

Often these devices claim to alter the combustion process in some way. Even assuming that this were possible, remember that the engine has been optimised for the "normal" combustion. To get any benefit from this "altered" combustion you would need to change fuel delivery, ignition timing or even the design of the cylinder head to suit! Diesel combustion is a lot more efficient than petrol combustion, but you can't just fill up your petrol car with diesel and expect a 20% economy improvement (no, don't even think about trying it - it will be very expensive to repair!)

A typical claim is that the combustion with the device fitted is somehow "better" or "more complete". There is never however any detail as to what is meant by this. And it is a firmly established engineering fact that, on any reasonably modern engine under normal operating conditions, the burn is already at least 98% complete. The unburnt fuel in the exhaust (even before the cat) represents 1 or 2% at most of the input fuel. If you factor in the energy in the CO emissions, the figure still only rises to 3% maximum. So even if the fuel "saving" device could totally eliminate unburnt fuel and CO in the exhaust, and give an absolutely 100% complete burn, you would only save 3% of fuel. Claims that 10%, 20% or even more of the fuel is not burnt and escapes into the exhaust are entirely false - the unburnt fuel figure is higher when the engine is stone-cold, and at high load and speed conditions, but since the engine only spends a small fraction of its time under these conditions their contribution to overall fuel consumption is small.

(NB That is not to say that the overall efficiency of a modern engine is close to 100%. There are losses due to the fundamental nature of the engine cycle (the "Otto cycle" or "Diesel cycle"), which limit even theoretical efficiency to about 40%, and there are also losses due to friction, heat loss to the walls of the cylinder and the piston, "pumping loss" due to sucking air past the partially-open throttle blade, etc. These losses are however well understood and the gains to be had from various technological changes are accurately known.)

The other reason why these devices can't work is simple business. Fuel consumption is a very hot topic in the European car industry at the moment, because it is directly related to carbon dioxide, which is a "greenhouse gas". Consumers and legislators are demanding ever-better fuel consumption from new cars. The industry is investing literally billions of pounds on more efficient engines, for example diesels (and we wouldn't do that if we were in the pay of oil companies, would we?) But these more efficient engines are also much more expensive to make - for example a diesel will produce about 15 - 20% less carbon dioxide, but adds about £500 - £1000 to the cost of a car. These "fuel saving devices" claim nearly as much benefit for a tenth of the cost - the car industry would not only sell its grandmother for this kind of saving, but sacrifice its first-born son too!

Given that, you have to ask why any such device isn't fitted to new cars as standard. The answer is simple - industry believes they are of no significant benefit. Otherwise, they would be on new cars. No question. The car industry has seen hundreds of these things go by, and can't afford to waste thousands of pounds on testing each and every one of them. But if you'd invented a miracle gismo like this and knew it worked, wouldn't you pay your own money on tests to prove it, given that you could then sell millions?

Some people argue that car makers are so keen to reduce costs that even the few pounds that one of these devices costs would be too expensive. And of course on some entry-level cars, and in cheap-gasoline America, there is some truth in that. But in Europe (especially in the UK with CO2-based company car tax) many consumers have proved willing to spend several hundred pounds more on a car if it is more economical. You need only look at the booming sales of diesels, which cost anything up to £1000 more than the petrol equivalent, for proof of this. There is a clear profit incentive for car makers to equip at least part of their range with more economical engines and so the potential market for a genuine fuel saving device runs into tens of millions of pounds a year. Sufficient incentive for any manufacturer of such a device to spend a few thousand on tests, you would think.

Exactly the same argument applies to the claims of increased performance made by many makers of such devices. For some car makers, even just one or two percent more horsepower is worth thousands of pounds. If a cheap and simple device like a magnet, air bleed, fuel "catalyst" or turbulence increaser could really give 5 - 10% more power, would they not be fitted as standard on most BMWs, Porsches, Ferraris, etc?

I have worked for or with some of the world's biggest car makers and component suppliers, and nobody I have spoken to in the industry has ever regarded these fuel "saving" devices as anything other than a con. They are never advertised in the journals aimed at engineers within the new car industry, the makers almost never present results at trade conferences, and no serious books on the subject (of which I have read dozens) even give them a mention. Certainly you don't find car engine designers saying to each other, "If only we could fit (device x) to our engine, but (company y) has got the patent on it". Even at normal market price these devices are allegedly massively more cost-effective than any known fuel-saving technology. Arguments about the difficulty of fitting them to new cars do not wash either, since current cars contain extremely complex devices that only a few years ago would have been considered impossibly difficult; the car industry has a good record of solving such problems.

You may well wonder, if these things don't do what they claim, why are the makers not prosecuted by (in the UK) Trading Standards or the Advertising Standards Authority? The answer is that many are, but it is difficult and expensive to prove the device doesn't work. The device usually then simply pops up again under a slightly different name claiming some slightly different technical features. For devices sold in the UK, it is however well worth while searching the ASA website, just in case. Remember that the ASA is effectively funded by the advertising industry, so does not make judgements against advertisers without good reason.
Several such devices proudly state that they are "award-winning!", to which I have just one comment: so were Milli Vanilli...

One more thing to remember is that thousands of scientists and engineers all over the world have been working on car engines for decades. The physics of engines is pretty well known now and you have to ask yourself if some amazing new breakthrough, only involving bolting something to the outside of your engine, would really have escaped the car industry's notice all that time.

The following pages give some more information on the types of "fuel saving device" you see advertised, and why they can't work as described (note that some devices claim more than one effect). I can't list every device on the market, because there are literally hundreds of them - in many cases the identical device sold under multiple names. Even if the device you're looking at isn't specifically listed, it almost certainly falls into one of these catagories:
Magnets round the fuel line or in the air flow (Ecoflow, FuelMAX, FuelSaverPro, etc)
Catalysts in the fuel line or tank (Broquet, Fitch Fuel Catalyst, Prozone, etc)
Platinum-based combustion enhancers (PVI, Gasaver, Ctech3000, etc)
Ignition enhancers (Fuel Saving & Power Push, Fireball Ignition, etc)
Air bleed into the inlet manifold (Ecotek, Khaos, Powerjet USA, etc)
Turbulence increasers (Ecotek, Tornado Fuel Saver, Powerjet USA, SpiralMax, etc)
Devices to "atomise the fuel better" (Ecotek, Tornado, SpiralMax, Vaporate, etc)
Oil additives (Slick 50, Duralube, etc)
Fuel additives to enhance combustion (Acetone, PowerPill, BioPerformance, etc)
Engine "cleaning" products (10k Boost, Powerboost, etc)
Electrical modifications (grounding straps, voltage stabilisers, etc)
Hydrogen generators

Magnets

Magnets round the fuel line or in the air flow

Devices of this type include: Ecoflow, FuelMAX, Prozone, MAXPower, FuelSaverPro, EcoMag, ZEFS

People have been claiming miraculous effects from magnets for hundreds of years. When considering these claims, bear in mind a simple physical fact: magnets only significantly affect things that conduct electricity. So magnets can affect metals, water and even the human body. But the only effect on a hydrocarbon fuel is the massively weaker "diamagnetic" influence. This would cause an extremely slight tendency of the fuel to move away from a magnet, but is highly unlikely to have any effect at the molecular level.

Some devices claim to "align the fuel molecules". But the molecules are vibrating at high speed all the time, just as in any liquid. So even if they were aligned in the magnetic field, they would "unalign" straight away when they passed the magnet, and so would be back to normal when they reached the engine. And where are the experimental results which show that the molecules are "aligned"? How can the makers claim their device works in a particular way, without any evidence to show that this is really happening?

Some magnet devices don't actually admit that they use magnets, because there has been so much negative evidence against them. But if a device clamps round the fuel line, doesn't have any electrical connection to anything, and claims to "align the fuel molecules" (or something along those lines), it is almost certainly a magnet. Devices made of neodymium, Samarium Cobalt or other "rare earth" materials are also almost certainly magnets.

But let's ignore the non-magnetism of fuel for a moment, and assume the magnet really does affect it. What is this claimed to do to the combustion?
A common claim is that it makes the fuel burn faster. Full details of the effect of burn rate on fuel consumption can be found on the turbulence page, but basically:

• Faster burning does not, even in theory, improve fuel economy significantly on modern engines (the burn rate is pretty close to optimum anyway)
• If the fuel really does burn faster, the ignition must be retarded to suit

Another claim is that the fuel in some way burns "better" or "more completely". But only about one or two percent of the injected fuel escapes unburnt from the engine (because it was trapped in the head gasket crevice, for example). The other 99% is totally broken down into smaller molecules, and then combined with oxygen to form water, carbon dioxide and carbon monoxide. Essentially all the chemical energy in the fuel is released as heat. How can the burning be any "better" than this?

The mechanism by which magnetic devices often claim to work is by converting long-chain fuel molecules to short-chain ones. It is of course true that petrol and diesel consist of many different molecules, ranging from large ones such as octane (C₈H₁₈) to small ones such as butane (C₄H₁₀). Longer molecules can in theory be broken down into shorter ones, though this process normally requires heat and pressure, as well as the presence of a catalyst. But even if the fuel "saving" device does break the molecules down, this does not imply improved fuel consumption or emissions.

Firstly, the precise blend of components of modern petrol (and indeed diesel) is quite carefully "tuned" to match the requirements of the engine. This even involves selling different petrol in summer and winter to compensate for differing temperatures! The proportion of the fuel that evaporates at different temperatures (the "boiling curve") is determined by the blend of high boiling point (long-chain) components and low boiling point (short-chain) components. If the proportions are altered, then the boiling characteristics of the fuel will change. The likely effects are either poor cold starting or poor hot starting, with increased emissions in each case.

Secondly, short-chain molecules do not generally produce significantly more energy when burnt. The calorific values of most hydrocarbon fuels are around 44 - 46 MJ/kg, with small molecules providing only slightly more energy than larger ones. Claims that smaller molecules burn "better", "more completely", or "more energetically" are not supported by experimental data (consider, for example, the fuel economy of LPG vehicles).

Some such products also claim a cleaning effect.

One of the best-known examples of a magnetic fuel "saving" device is the Ecoflow. In 2002 the Advertising Standards Authority ruled against Ecoflow, saying:
The Authority took expert advice on the Warren Spring [DTI] report. It understood that the testing procedure was flawed and therefore the results did not prove the efficacy of the Ecoflow fuel economiser. It considered that the letters, testimonials and articles sent by the advertisers to support their claims for the fuel economiser did not constitute rigorous scientific evidence.
The vehicle tested, a non-catalyst equipped carburetted engine car, was not typical of current vehicles, which are fitted with catalysts and fuel injected systems. The Authority noted the vehicle tested was too old and too variable in its exhaust emissions for the test programme used. The Authority concluded that the reference to the Warren Spring report was misleading because the testing procedure was flawed and the test vehicle no longer representative. It told the advertisers to delete the reference to the Warren Spring report
The ASA does not regulate Internet advertising, so this test data is still widely used by the sellers of magnetic devices ("tested by the DTI!"), but the authoritative remarks above should demonstrate the need for caution in accepting these claims.
Ecoflow also said that their magnetic device was "the subject of a continuing product specific trial funded by an independent charity" but "the results would not be available for some time". This was said over two years ago - readers may draw their own conclusions as to the results of this trial, from the fact that they have apparently not been published.

Another "famous" magnetic fuel "saving" device is the FuelMAX / Super FuelMAX. The makers and sellers of this device were recently taken to court by the US Federal Trade Comission, and banned from claiming significant economy or emissions benefits. Read the FTC press release for full details. (The "FuelMAX" was described by the FTC as "a bogus fuel-saving product that doesn’t save fuel", which is a pretty clear condemnation!) And in August 2006 the company was fined 4.2 million dollars for their false claims, and banned from ever selling such products again.

Interestingly, certain makers of both magnet and catalyst-based fuel "saving" devices claim that they were used by the RAF during World War 2. Amazing that the British armed forces should have found not one, but two, miraculous fuel-saving devices; even more amazing that they have apparently now "lost" both of them. (Since getting fuel to the front line is a major logistical problem, the armed forces are more interested in fuel consumption than you might think.) A sceptic might wonder how much truth there is in either claim.

On a related note, ask yourself why such magnets are not fitted as standard on aircraft. Since fuel is a very high proportion of an airline's running costs, you would think they would jump at the chance to save 10%+ on fuel consumption just by adding a relatively cheap magnet round the fuel line. Magnetic fuel "saving" devices typically claim to work on petrol engines, diesel engines and gas boilers, so why should they not work on jet engines?

Magnets are also often claimed to be useful either medically (reducing pain, etc) or for reduction of "scale" in hard water areas. I am sceptical about both of these claims, but since water undoubtedly can be affected by magnets (and the human body is mostly made up of water) there is at least a hint of a possible mechanism by which they might work. This absolutely does not add any weight to the idea of magnets affecting hydrocarbons fuels, however
Magnets are additionally claimed to improve the efficiency of gas boilers. The Energy Saving Trust conducted an (admittedly relatively small-scale, but carefully controlled) study of this and could find no effect from magnets on boiler efficiency or emissions. I have a copy of the report but the EST have requested that it not be "published" and so it is not available on this site. Of course this is not proof that magnets do not work on gas boilers, or that they do not work on car engines, but it is certainly a strong indication in that direction. As with car engines, there is strong pressure (in Britain in particular) for boiler makers to deliver good efficiency ratings. If simply adding a magnet could greatly improve efficiency, boiler makers would fit them as standard on most models.

Skeptical Enquirer magazine has an interesting article on magnetic fuel and water treatment, including commentary on the lack of published data as to its effectiveness.

Please also read the general comments on fuel "saving" devices, if you have not done so already

Fuel "catalysts"

Fuel "catalysts"

Devices of this type include: Broquet, Fitch Fuel Catalyst, Prozone, Fuelcat, Enviromax Plus, Vitalizer, Firepower, PICC, Euro FuelSaver

A vast array of usually tin-based products, either dropped in the tank or fitted in the fuel line, claim to improve the fuel quality and so improve power and economy. (NB This page is about "fit and forget" devices; for information on products to be added at every tank fill, see the fuel additives page.)

Some of these products claim to allow the use of unleaded petrol in leaded-only engines. That is largely outside the scope of this site, but it is worth noting that this is quite a difficult claim to prove through purely anecdotal evidence, since many "leaded-only" engines would in any case survive running on unleaded fuel providing they were only ever driven gently (which could be the case with a cherished classic).

Turning away from this issue, there are two basic questions to be answered:
a) Can a tin-based catalyst affect fuel properties?
b) Can such a change give a significiant fuel economy improvement?

For the first question, an important point to note is that tin is not generally regarded as an efficient catalyst for hydrocarbons. The "catalytic cracking" systems in oil refineries often cited by makers of these devices in fact use Zeolites, composed mostly of aluminium and silicon. The catalytic converters in vehicle exhausts use platinum, rhodium and palladium. Tin is not a major consituent of either type of product - although some prominent "mainstream" companies have proposed fuel catalysts where tin is present to some extent.

The mechanisms by which tin catalysts are claimed to work are quite varied, and include both claims to alter the basic properties of the fuel before it enters the engine, and claims to alter the combustion process due to the presence of microscopic particles of tin / tin compounds in the fuel. It is true that at least some makers of such devices do have data that appears to show changes in fuel properties, either by conventional analytical techniques such as mass spectroscopy or other tests such as thermal stability, and there is also a plausible mechanism whereby tin catalysts could reduce bacterial growth in fuel (various compounds of tin beinq quite toxic). What is considerably less clear to me is whether these changes are significant, or indeed beneficial, to engine operation.

The basic problem is that modern engines are optimised around the combustion of "normal" fuel and changes to the fuel properties and/or combustion process, even if theoretically beneficial, are unlikely to give significant fuel economy benefits unless the engine design and/or engine management system settings are adjusted to suit. An obvious example would be speeding up the burn - while this may have some benefit under at least some conditions, it is essential to retard the spark (petrol) or injection (diesel) timing to keep the central part of the burn occuring at the optimum time. Without this retard (which is very unlikely to occur automatically, even on the most advanced car / light truck engines) the result is likely to be worse fuel economy or even engine damage. It is also surprising that not one maker of such products, so far as I can tell, has been willing to back up claims of a faster burn with the relatively cheap and simple tests needed to actually measure burn rate and show that it has changed. Likewise, increasing octane rating of petrol (gasoline) can in theory improve performance, but only on the few engines that can take advantage of this.
The mechanism by which catalytic devices often claim to work is by converting long-chain fuel molecules to short-chain ones. It is of course true that petrol and diesel consist of many different molecules, ranging from large ones such as octane (C₈H₁₈) to small ones such as butane (C₄H₁₀). Longer molecules can in theory be broken down into shorter ones, though this process normally requires heat and pressure, as well as the presence of a catalyst. But even if the fuel "saving" device does break the molecules down, this does not automatically imply improved fuel consumption or emissions.

Firstly, the precise blend of components of modern petrol (and indeed diesel) is quite carefully "tuned" to match the requirements of the engine. This even involves selling different petrol in summer and winter to compensate for differing temperatures! The proportion of the fuel that evaporates at different temperatures (the "boiling curve") is determined by the blend of high boiling point (long-chain) components and low boiling point (short-chain) components. If the proportions are altered, then the boiling characteristics of the fuel will change. The likely effects are either poor cold starting or poor hot starting, with increased emissions in each case.

Secondly, short-chain molecules do not generally produce significantly more energy when burnt. The calorific values of most hydrocarbon fuels are around 44 - 46 MJ/kg, with smaller molecules producing only slightly more energy than larger ones. Claims that smaller molecules burn "better", "more completely", or "more energetically" are not supported by experimental data (consider, for example, the fuel economy of LPG vehicles).

General claims of making the burn "more complete" should also be considered with some scepticism, since only about one or two percent of the injected fuel escapes unburnt from the engine (because it was trapped in the head gasket crevice, for example). The other 99% is totally broken down into smaller molecules, and then combined with oxygen to form water, carbon dioxide and carbon monoxide. Essentially all the chemical energy in the fuel is released as heat. How can the burning be any "better" than this?
Where a "more complete" burn might genuinely give benefit is in the reduction of toxic pollutants, especially diesel smoke. Increasing the percentage fuel burnt from 98 to 99% gives an almost immeasurable improvement in economy, but halves the emissions of HC / CO / smoke (all of which are partially or totally unburnt fuel). The production of diesel smoke / soot in particular involves some highly complex reactions, and a mechanism that enhances the conversion of soot particles to CO2 could give a worthwhile reduction in exhaust smoke. The fact that various metallic compounds are used to promote soot-burn off in some diesel particle filters gives some credence to this theory, and some makers of tin-based fuel catalysts have apparently robust data to support smoke reduction in certain applications.

Various products also claim a cleaning effect.
Some commentators claim that the various catalysts work very well in theory, but the evil oil companies specifically add products to their fuel to "disable" them. Even if true (which would be easy enough to prove by carrying out scientific tests on the product using an alternative fuel), you have to ask why these catalytic products are not simply sold in other countries where the fuel blend is different.

In conclusion, it seems that there is reasonable evidence to conclude that at least some tin-based catalysts do affect fuel, and it is not implausible that some beneficial changes - most notably diesel soot reduction - occur as a result. There is even some evidence of very modest (no more than 5%) fuel economy benefit on at least some engines under at least some conditions - while the evidence so far has not been entirely robust, an improvement of this size is just about within the range of what might seem plausible given the changes described above.

There is, however, also plenty of evidence for complete lack of effectiveness. For example, when the Fitch Fuel Catalyst was tested in February 2008 by the Australian motoring organisation, the NRMA, essentially no benefit in either emissions or fuel consumption was found on the two petrol (gasoline) vehicles tested. Supporters of this technology claim that the tests were flawed in some way - either due to incorrect installation, or insufficient "conditioning period" between installing the device and performing the test. While this cannot be disproved, the negative results still represent a significant challenge to the makers of such devices.

Interestingly, certain makers of both catalyst and magnet-based fuel "saving" devices claim that they were used by the RAF during World War 2. Amazing that the British armed forces should have found not one, but two, miraculous fuel-saving devices; even more amazing that they have apparently now "lost" both of them. (Since getting fuel to the front line is a major logistical problem, the armed forces are more interested in fuel consumption than you might think.) A sceptic might wonder how much truth there is in either claim.

Use in other applications: my field of expertise is engines for cars and light trucks, and that is the central subject of this Web site. Many people claim benefits from their "fuel catalysts" in very different applications such as large marine engines and industrial burners; I remain sceptical of these claims, but cannot comment definitively on them as I have little experience with such applications, and there are significant differences to car / light truck engines.

(NB AdBlue is a quite genuine additive that will be used to enhance catalytic reduction of NOx emissions on many future diesel trucks. Negative comments on this site regarding fuel additives and "catalysts" do not in any way refer to AdBlue, which is only of use on engines specifically designed for it.)

Please also read the general comments on fuel "saving" devices, if you have not done so already

Platinum injection

Platinum-based combustion enhancers

Devices of this type include: PVI, Gasaver, CTech 3000, FuelSaverDevice

All modern petrol cars are fitted with catalytic converters, which contain small amounts of the precious metals platinum, rhodium and palladium. These metals act on the exhaust gases and promote conversion of toxic chemicals such as unburnt hydrocarbons to more benign substances such as water and carbon dioxide.

Various companies have noted this technology and devised systems to deliver small quantities of platinum (and other metals) to the engine along with the intake air, the theory being that the catalysts will also act in the combustion chamber to promote faster and more complete burning. The typical claim is that around 20% of the intake fuel is not burnt in the engine, but escapes and is burnt in the catalytic converter where it just produces useless heat. By adding the platinum to the combustion mix, supposedly this unburnt fuel fraction is greatly reduced.

In principle there is some sense to this. Some respected research institutions have investigated catalytically coated pistons which aim to act in the same way to reduce unburnt hydrocarbons. However in practice this technology is - like all other fuel "saving" devices I have investigated - deeply flawed.

The first and most fundamental point is that the unburnt fuel fraction in a modern engine under typical operating conditions is far less than 20% - around 2% is much more usual. That is to say, only one fiftieth of the injected fuel escapes unburnt from the engine. The remaining 98 - 99% is completely broken down into smaller molecules and burnt to form carbon dioxide and water. So even if the device could significantly reduce this unburnt fuel fraction, the overall fuel saving would be extremely small.

If it really were true that around 20% of the fuel was being burnt in the catalytic converter, you would expect the gas emerging from the cat to be much hotter than that entering. I have worked on dozens of vehicles equipped with "pre-cat" and "post-cat" thermocouples, and have never seen a significant temperature rise except under fault conditions such as a misfire. Indeed, if you turn off ignition to one cylinder of a V8 engine (so that 12% of the fuel is burnt in the catalyst) then the heat release is so great that the catalyst would be quickly destroyed when the engine is at full power. To suggest that 20% is burnt in the catalyst under normal conditions is just not true.

The second point is that any true catalytic influence on the combustion must cause it to speed up. That is the definition of a catalyst, and is also the only plausible means by which the burn could be made more complete. However, the ignition timing on any engine is carefully optimised to suit the burn rate of the fuel/air mix. If the burn rate is altered, then the ignition timing must be altered to suit - yet no makers of platinum combustion enhancers suggest changing ignition settings.

An interesting aside is that all the systems I have seen advertised use engine manifold vacuum to draw the platinum solution into the engine. This means that the larger the vacuum, the more platinum is injected. However, the air flow into the engine is smallest at high vacuum, and largest when there is no vacuum at all (wide open throttle). So the amount of platinum added to the engine is inversely proportional to the amount of fuel and air taken in! At very light loads the platinum fraction is relatively high, at full load there is none at all. One might then wonder how the device can function optimally under all conditions. (A correspondent pointed out to me that using the vacuum between the air filter and the throttle would solve this problem - which it would, but it would also introduce other problems.)

The proof of such devices is, of course, in the test results. As usual, makers of platinum combustion enhancers quote many apparently impressive customer testimonials and on-road fuel economy results, but these do not represent any sort of proof (see general comments here). However, the "original" platinum-based fuel "saving" device - the "PVI" system - has however been scientifically evaluated by the US Environmental Protection Agency - here is their report (pdf format). The conclusion was that the device had no significant effect on either economy or emissions. Following this testing, the company was fined $75,000 in 2002 for making false claims (and subsequently lost their 2004 appeal as well.) The Canadian Broadcasting Corporation also ran an excellent story on the "PVI" system in 2002, which makes for interesting reading.

The apparently very similar "Ctech 3000" in the UK was also heavily criticised by the Advertising Standards Authority in July 2005.

Does this prove that all platinum combustion enhancement fuel "saving" devices are worthless? No, but since they all seem to be broadly similar in operation and claims, it does strongly point in that direction.

NB Since the devices usually also pass air into the inlet manifold, you may see effects similar to air-bleed devices - which may include reductions in HC and CO emissions at idle on older cars. These apparent emissions reductions do not, however, imply that the device is operating in the claimed manner.

Please also read the general comments on fuel "saving" devices, if you have not done so already

Ignition enhancers

Ignition enhancers (petrol/gasoline only)

Devices of this type include: Fuel Saving & Power Push, Fireball Ignition, Motorspark, "Cryogenically treated" spark plugs

Petrol engines rely entirely on the spark to ignite the fuel/air mixture and provide power to drive the vehicle. If this spark is unreliable - for example, if it is too weak to always jump the plug gap - then the engine will misfire. This misfire represents fuel simply passed down the exhaust pipe unburnt.

So far, so good. In the "bad old days" of contact-breaker ignition, devices to improve ignition energy could improve spark reliability, especially under cold or damp conditions. You could see real improvements in fuel consumption and / or power. But modern electronic ignition systems are extremely powerful anyway and provide at least 99% ignition reliability. If they didn't, the emissions of unburnt fuel would far exceed the amounts allowed by emission legislation. Adding more ignition energy might perhaps provide an absolutely immeasurable improvement in fuel consumption, but at the expense of increased spark plug wear.

One particularly interesting concept is the Meissner Spark Intensifier (invented in the early 1900s) and many similar re-inventions since. Put simply, this is a small air gap in the HT lead between the coil and the spark plug - devices that require you to cut the HT line are likely to be of this sort. The Spark Intensifier may perhaps give better igntion reliability if spark plugs are heavily fouled, but this is very rarely the case on any modern engine. In any case, simply replacing the plugs would be a better (and usually cheaper) solution to this problem.

Fundamentally, once the mixture is lit, it's lit. A fire doesn't burn hotter because you use a bigger match to light it; a bigger spark won't make the fuel/air mixture burn any hotter either. I have carried out many engine experiments involving changing ignition energy, and while there are some marginal benefits in extreme conditions (cold, damp, etc), the overall effect on power and fuel consumption on any modern engine is negligible.

Some devices also claim to make the mixture burn more quickly. Even if this were possible (and it is most unlikely), a faster burn does not usually translate into better fuel efficiency. See the turbulence page for more information. Indeed, a more rapid burn might actually be damaging to an engine because it could promote knock unless the ignition timing is retarded appropriately.

Please also read the general comments on fuel "saving" devices, if you have not done so already

Case Study: the Khaos Super Turbo Charger (KSTC)

Case Study: the Khaos Super Turbo Charger (KSTC)
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.

Update April 2010: 5 years on, I have finally been sent what appears to be the Australian (Vipac) test results, which are (so far as I can tell) not available anywhere on the Internet. I do not have permission to post them, though I am trying to get this permission. All I can say at this stage is that they do not seem to support claims of large fuel economy improvements on modern (ie with fuel injection and catalysts) vehicles.

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.

NB Nothing on this page should be taken as an accusation of deliberate fraud by Mr Planas or Khaos. I strongly believe Planas is sincere but misguided - a perfect example of the old adage "a little knowledge is a dangerous thing".

Both supporters and sceptics are of course welcome to contact me for further discussion. There is also a long and detailed discussion about KSTC on the tsikot.com Forum.

Please also read the general comments on fuel "saving" devices, if you have not done so already

Case study: The Ecotek CB-26P

Case study: The Ecotek CB-26P

In general, I have avoided discussion of specific devices on these pages, and concentrated on generic technologies. But the case of the Ecotek CB-26P is especially interesting, since it has a very high profile on the Web and much background information is available, so this page focusses on this particular device.
Important background information. For the avoidance of doubt, readers should bear the following in mind:

1. This Case Study is not an unbiased review of the CB-26P; as is clear from other pages on this site, I have a very sceptical view of all aftermarket fuel "saving" devices, and this Case Study focusses on the negatives (ie what it does not do, rather than what it does do).

2. I have mainly considered issues of fuel economy (as the site name suggests), rather than the aspect of performance (in particular "driveability") that now forms the main selling point of the device.

3. Criticism of Ecotek's claims for the device is more aimed at their previous claims (which are unfortunately still widely repeated on the Net) rather than the current advertising.

Ecotek's CB-26P is an example of a device which bleeds air into the inlet manifold. For full details on this sort of device see this page, but in summary, it adds extra air to the engine under certain conditions and so adjusts the air:fuel ratio. On an engine that often runs "rich" (as many engines did before 1993), this could perhaps give genuine benefits.
It is instructive at this stage to consult Ecotek's patent application (pdf format). The important paragraphs are:

Typically the engine is tuned when at an idling speed, known as tickover, and the engine is tuned such that is operating optimally when ticking over. It is the only practical method of tuning the engine but once the engine is operated at speed and under varying load conditions it is not optimally tuned for such conditions and thus a degree of unburnt fuel is emitted from the exhaust of the car thus reducing the engine efficiency. 

There is provided a combustion mixture control apparatus for a spark ignition internal combustion engine comprising an auxilliary air valve ... [to] cause the air to fuel ratio taken in by the engine to be in the range of 13:1 to 15:1 and preferably in the range of 14.4:1 to 14.7:1.
The auxilliary air valve of the invention will act as a combustion mixture control apparatus to optimise or near optimise the air-fuel mixture in the manifold and thus the cylinders at all times during the operation of the engine. This in turn will reduce the emissions of unburnt fuel and partially combusted fuel from the exhaust of the engine thus reducing the emissions of carbon monoxide and hydrocarbons into the atmosphere. 

...and another half a dozen or so references to optimising the air/fuel ratio.
This wording in the patent application strongly suggests that the design purpose of the valve is, as I describe on my page, to lean the mixture off under certain conditions. There is some sense in this idea: some readers may remember having to turn the "mixture adjusting screw" at idle to get the right CO reading (which is a measure of air-fuel ratio or lambda). The lambda or air-fuel ratio achieved at loads and speed other than idle would depend on the carburettor jet / needle settings, and indeed frequently was not ideal.

Tellingly, until very recently the primary evidence for improved fuel consumption was the 1993 Warren Spring test data. This testing was carried out on a 1988 vehicle with a carburettor - this sort of vehicle might very well run too rich under normal operating conditions and so show some benefit when the Ecotek was added. The device was developed at a time when carburettors were almost universal.

So, that is all quite clear and consistent. But the critical point is that this absolutely does not describe how a modern (1993 onwards) engine works. The carburettor has been consigned to the dustbin, replaced by a computer-controlled injection system that allows the engine designer to precisely specify the desired lambda at all load and speed points. The lambda sensor in the exhaust corrects for any small deviations under most operating conditions, and indeed the "idle mixture adjustment control" simply does not exist on any post-1993 European petrol car. The mixture is already at optimum (or very nearly so) under almost all conditions, not just at idle, and so mixture adjustment as a way of significantly improving fuel economy is all but impossible.

Yet the CB-26P has not generally been marketed in the past as a device only suitable for pre-1993 vehicles, indeed Ecotek's technical pages have frequently actively denied that the device works by adjusting the air/fuel ratio. Instead the usual claim has been that the main effect is increased turbulence [swirl] (as you can see from the reviews) - which is not mentioned anywhere in this or any other patent application. Nor have Ecotek presented any test data to actually show that turbulence is increased (despite repeated challenges), although measurement of turbulence is a relatively straightforward test routinely used by many engine designers. A cynic might believe that is because they do not have any test data showing increased turbulence, which then makes you wonder how they can make such a claim.

It is true that adding in-cylinder turbulence can have a very slight benefit on fuel consumption and emissions - this page gives more information. But the maximum benefit is only around 2% given the reasonably high turbulence levels that exist in modern engines anyway. More fundamentally, the biggest effect of increased in-cylinder turbulence is a faster burn. By the time you have enough turbulence to affect economy, you must retard the ignition by typically 10 - 20 degrees to compensate for the increased burn rate.

A further claim typically made by Ecotek is that it improves fuel atomisation which makes the burn more complete. Again Ecotek do not present any test data to actually show that atomisation is improved, though this is not too difficult to directly measure. And it ignores the fact that atomisation on any reasonably modern engine is already very good, and the burn is typically 98% complete under normal cruising conditions. Thus the potential for fuel saving is extremely small. See this page for more information about fuel atomisation.
So, in summary:

• There are strong theoretical reasons to believe the CB-26P does not significantly increase turbulence
• There is no test data to show that it does increase turbulence
• Both theoretical and experimental understanding of engines says that increasing turbulence would not, in any case, give the 10-15% economy benefit typically claimed
• The device undoubtedly does lean off the mixture on most pre-1993 vehicles, and this could be responsible for at least part of the improvements observed

Turning away from the technical aspects, Ecotek set great store by the many magazine reviews shown on their web pages. Quite apart from the obvious point that negative reviews are not reproduced here, none of these reviews contain any scientific test data. We have emissions measurements at idle or fast idle, almost always without NOx, and fuel consumption measured on the road under totally uncontrolled conditions. And of course many of the positive comments, especially from the "modding" end of the market such as Max Power, are more to do with driving "feel" than economy or emissions. That the CB-26P can affect the "feel" of at least some cars is not in doubt, though the change may well not be for the better. Finally, many of the reviews and testimonials are for pre-1993 vehicles, and so may not be applicable to newer cars.
There is a general issue as well, that magazine writers are not normally technical engine experts and so may not be qualified to judge this or other fuel "saving" devices accurately. That's not meant as a personal criticism - nobody can be an expert on all aspects of cars, for example I know very little about ride & handling. But beware of assuming that all car magazine writers are technical experts on all aspects of vehicle engineering, as this is simply not the case.

A common opinion voiced by Ecotek as well as other makers of fuel "saving" devices is that everyone who tries them is convinced, while the critics are all people who have not tried them. And of course the makers and sellers of Ecotek and other similar devices display entirely positive testimonials on their sites, which seem persuasive at first glance. But the important thing to remember is that the reported benefits are almost entirely based on perceptions and uncontrolled tests, and hence show large variability (see this page for general comments on fuel consumption variability). It is not suprising that some users perceive a benefit, but equally it is not hard to find negative reports from actual users on the Internet. For example, from the Clio Sport forum:
Just removed the Ecotek valve. The car pulls harder, brakes better and runs quieter than before. If anyone has an Ecotek I'd strongly suggest removing it...let the ECU do what it's designed to do
Took mine off after running it for about 6 months, made a massive improvement. Waste of money!
People frequently ask why I criticise the CB-26P without having personally tested it. The reason is that I could fit one to my car but it would prove absolutely nothing. Any fuel economy effect would be lost in the variation of normal driving. The emissions tests I could do (basically CO and HC at idle, as measured on the MoT test) would say nothing at all about the effect on overall emissions while driving, and hence environmental impact. Proper performance testing would require multiple rolling-road tests with and without the device, which would be expensive and time-consuming. For these reasons, I also believe the customer testimonials often quoted by Ecotek to be of little value.

Readers looking for an independent view of the CB-26P may like to note that the Advertising Standards Authority ruled against Ecotek on 21st April 2004. The full adjudication is quite long, but in summary, the ASA believes Ecotek do not have any credible evidence that the device does in fact improve economy, emissions or performance. As a result Ecotek are effectively barred from making these claims in normal print advertising (magazines etc).

Important update - March 2005. For well over a year, this site has consistently stated that the CB-26P can have very little effect on the emissions or economy of lambda-controlled engines (post-1992 in Europe), for the reasons explained above. Ecotek have in the past always denied this, and as recently as December 2003 claimed fuel economy improvements of around 15% on "anything other than the very newest vehicles". They also "guaranteed" fuel economy and emissions benefits, and indeed many resellers and marketers typically claimed 15% economy benefits on all vehicles.
Under pressure from both the ASA and this site, Ecotek finally conducted a series of proper scientific emissions and economy measurements over standard drive cycles on modern cars. The results can now be found on Ecotek's site - and indeed prove that the CB-26P gives little or no economy and emissions benefit on a more modern vehicle.
The summary of the results is as follows:

• Fuel consumption (and hence of course CO2) around 1% better
• NOx generally slightly increased (about 5%)
• HC and CO generally slightly reduced (about 10%)

The critical result here is of course the improvement in fuel consumption of just one percent - something like a tenth of the benefit previously claimed by Ecotek. Even if this result represents a genuine technical improvement rather than simply random test-to-test variation (see comments on statistical significance), that means the device is extremely unlikely to ever pay for itself in fuel savings. Ecotek do claim that there will still be benefits on lambda-controlled cars "at higher speeds where the Lambda goes open-loop and the AFR controls switch off", but they do not seem to have any evidence for this. Lambda control is generally active under all cruising conditions, with the engine only going "open-loop" at close to full load. Under these high load conditions, there is almost no manifold vacuum to suck air through the CB-26P and so any effect on the engine will be minimal. Furthermore, it should be remembered that the EUDC test cycle over which these vehicles were run covers the speed range up to 120 km/h (75 mph) and so cannot be considered as just low load and speed. (This is especially true given that the cars tested were relatively low-powered; the EUDC cycle demands acceleration from 62 to 75 mph in 20 seconds, while the Ford tested takes over 10 seconds to do this absolutely flat-out.) If the device really could work in the real world, one would expect to see the benefit on this test as well.
An additional argument made by Ecotek is that the device will give benefits on 1993-1995 "Euro 1" engines, since the lambda control is in some way less effective than on the "Euro 3" cars tested, hence allowing the CB-26P to "manipulate" the AFR more. Having worked on engines covering Euro 1 to Euro 4, this seems highly unlikely - the fundamentals of lambda control are the same on all catalysed vehicles, and any differences are likely to be small. One might also wonder why Ecotek did not simply choose to include a "Euro 1" vehicle in the test group, if this really is such an important factor.
In terms of toxic emissions (HC, CO, NOx), there is no clear trend - the best that can be said is that emissions with and without the device fitted are broadly similar. An obvious conclusion from this is that the CB-26P is not significantly affecting the combustion process (either for better or for worse), which again suggests that Ecotek's claims of swirl and turbulence effects are untrue. The lack of a significant rise in NOx shows that the lambda controller in the ECU is doing its job and compensating for the extra air flowing through the device.

In summary: even on cars chosen by Ecotek, with the CB-26P tuned by them and the tests under their overall control, they can only demonstrate tiny economy and emissions benefits on a lambda-controlled vehicle. The sceptics, such as myself and the ASA, have once again been proved correct!
A more general point is the relevance to other fuel "saving" devices. If you search the Internet you will find hundreds of people convinced that they have seen 10%, 20% or even greater fuel economy benefits on lambda-controlled cars through fitting the CB-26P. Yet when the device is scientifically tested - all conditions kept constant, except for the presence or absence of the device - the apparent benefits all but disappear. The conclusion must be that users who reported these large economy improvements were either mistaken, or were fooled by other changes such as driving style, journey type, etc. This should be borne in mind when looking at "testimonial" evidence for other fuel "saving" products.
To be fair to Ecotek, since this test data was obtained they have shifted the advertising focus of the device to its performance benefits, and have largely dropped claims that it will save useful amounts of petrol (or greatly reduce emissions) on lambda-controlled vehicles. Unfortunately not all marketers and resellers of the product are so scrupulous, and it is still common to find "saves 15% on ANY car!" as a claim for the device. Such claims should clearly be taken with a very large pinch of salt.

The other aspect of the Ecotek CB-26P is the claims of increased performance. Most fuel "saving" devices make some claim of a performance increase, but the CB-26P is regarded by many as a primarily a performance mod, with the fuel saving almost a side benefit.
The argument why it can have very little (if any) effect on performance is set out in detail on this page; in summary, there is very little manifold vacuum at wide-open throttle, and so the air flow through the device is negligible and its effects essentially zero. (As an aside, worries that the device will lean off the mixture at full throttle and cause overheating damage are therefore probably groundless.) In fact, even Ecotek themselves do not actively claim a performance increase in the usual sense - that is to say, an increase in engine power or torque. The only rolling-road data on their website (from VW Motoring) quotes a 1 to 2% increase in BHP, which would be totally imperceptible to the average driver and almost certainly within the test-to-test variability of the rolling road.
Why, then, do so many users report that their car feels faster? A large part may well be psychological - especially since the device makes a loud "slurping" noise while working. Modifications, particularly ones that change the volume or character of the engine's sound, are widely considered to lead to an improvement in perceived performance. However the device does have an effect on the "driveability" of the car, which may be perceived as a performance boost.
On many modern cars, there is no direct connection between the accelerator pedal and the throttle blade. The pedal sends a signal to the ECU, which moves the blade as it sees fit (the so-called "fly-by-wire" system). This allows the engine designer free choice as to how the blade should react to particular pedal inputs, and this "driveability calibration" is responsible for much of the "feel" of the car. For example, when the driver suddenly lifts off the pedal (to slow down or change gear), there are two possible responses:
1. Snap the throttle blade shut immediately, bringing the engine quickly down to its minimum torque output. This gives a very "sharp" response and plenty of engine braking, which is often desired. But because the engine has been so strongly throttled, there is a slight delay after the driver re-presses the pedal before full torque is available again. This is sometimes referred to as a "flat spot", and is particularly evident on less sophisticated systems that struggle to keep emissions under control during rapid throttle movements.
2. Close the blade gradually, and not so fully (on non-fly-by-wire systems, a similar trick can be pulled with the idle control valve). This keeps a higher engine torque and so the response to the pedal being pressed again is more rapid. However, it gives a feeling that the car is "running on" with no engine braking, which many drivers find very unpleasant, and also slightly increases fuel consumption.
The ideal response is entirely down to the preference of the driver. It is however true that behaviour (2) gives smoother power delivery through gearchanges (since the engine doesn't "die" during the change) and so may give a slight improvement in through-the-gears acceleration. Engine designers look for a compromise between (1) and (2) to give sufficient engine braking and smooth gear changes, but do not always succeed.
How is this relevant to Ecotek? Basically, the CB-26P valve acts as a leak round the throttle, simulating a larger throttle opening and so changing from behaviour (1) to behaviour (2). If your car is set towards (1), and if you prefer (2), then you may like how your car drives with the Ecotek better. But this not a "real" performance increase in the "traditional" sense, as the rolling-road data mentioned above makes clear.

Important update - March 2005. For well over a year, this site has consistently stated that the CB-26P can have very little effect on "real" performance, for the reasons described above - the only likely benefit would be slightly faster through-the-gears acceleration due to less "throttling" during the gearchange. In Feburary 2005 Ecotek carried out a series of performance tests, the results of which can be found here. In many ways this test program was very well designed and carried out - the Datron equipment used is highly regarded in the automotive industry, and by evaluating the results from 10 mph rather than rest the inevitably highly variable "take-off" is eliminated.
Unfortunately one critical aspect of the testing was missed - the A-B-A check. It is not sufficient to show an improvement when a device is fitted; you must then remove it again and show that the improvement goes away. Otherwise it is possible that some entirely unrelated external factor was responsible for the change. In the case of Ecotek's performance testing, this factor might be:

• Wind (even just 10 mph would have a very significant effect at higher speeds)
• Temperature of oil, coolant, tyres, etc
• Fuel level (just one gallon of petrol - easily used during the course of performance testing like this - would alter the weight and hence acceleration of these cars by about 0.5%)
• etc

Of course, quite possibly none of these factors changed during the testing - but without an A-B-A test it is impossible to know. Even taking the results entirely at face value, it is clear that the absolute improvement in performance is not highly significant - about 3% in most cases. To put that into context, it would equate to:

• Adding two additional horsepower to the engine
• Lowering air temperature by 10 celcius
• Raising air pressure by 25 mbar
• Removing about 5 gallons of petrol from the tank

Most drivers would find it impossible to detect a change of this magnitude; certainly the test results do not appear to justify Ecotek's previous claims of "transformed" performance. The implication is that the improved performance noted by some Ecotek users is much more due to altered "feel" and speed of throttle response, rather than actual objectively better performance. Some drivers undoubtedly do prefer this altered feel, and for them the CB-26P probably does justify its purchase price. But it should always be understood that this is primarily a change in the character rather than amount of performance. (More positively, this change in performance characteristic does not seem to come at the expense of increased fuel consumption or emissions - unlike some performance modifications).

Footnote
Ecotek's lawyers wrote to me at the end of April 2005 to complain that this site was "unbalanced" in its treatment of the CB-26P. It is of course true that I have focussed here on the negative aspects, though I would strongly deny that any of the analysis is incorrect or different to normal industrial and scientific practice. However, in the interests of fairness, I suggest that potential customers either visit Ecotek's own web page, or indeed their Forum, for the "other side" of the story. Suggestions from Ecotek for changes to this site to improve accuracy remain welcome, although I make no guarantee that they will be implemented.

Please also read the general comments on fuel "saving" devices, if you have not done so already