Fuel Saver - Snake Oil Or Not ?

The SMH has an article about a new device that can reputedly reduce petrol consumption and greenhouse emissions by 20% from a company called Moletech. Their marketing campaign at the CES show seems to have been very successful, getting the attention of sites like Engadget.

Unsurprisingly, to my cynical eyes, the article is very short on details about how this feat is achieved. While I'd like think we could get a significant boost to both improve fuel economy and lower emissions so easily, it does rather sound like snake oil, all protestations to the contrary. On the subject of miracle fuel saving technologies, what happened to high profile (last year) company Firepower ?

The retired founder of the Strathfield retail group is going global with his next big project – a fuel saver device that cuts weekly petrol costs by up to 20 per cent and significantly lowers greenhouse gas emissions.

Andrew Kelly, now chief executive officer of Moletech, says his patented Fuel Saver kit is easily installed in any fossil-fuelled vehicle and improves fuel efficiency by changing the properties of gasoline in the tank. No modifications to the original structure of the vehicle are required.

Many have tried and failed to produce a product capable of noticeably improving fuel efficiency and reducing toxic emissions, but Kelly insists he isn't selling snake oil.

According to an assessment of Fuel Saver by associate professor Peter Dingle, of the environmental science department at Australia's Murdoch University, the technology has been independently tested in Australia, China, USA and Taiwan with positive results.

"The test results show enhanced combustion leads to a 20 per cent increase in fuel efficiency, a significant and large decline in toxic hydrocarbons, nitrogen oxides and carbon monoxide, and a minimal 20 per cent decrease in greenhouse gases," Dr Dingle wrote. He concluded Fuel Saver demonstrated benefits for all car users and widespread installation would benefit Australians health, environment and economy.

For six cylinder or V8 vehicles a Fuel Saver kit costs $399, while a cheaper $299 kit is available for four cylinder cars. There are different versions of the product depending on whether the vehicle takes gasoline, diesel or LPG. ...

The Fuel Saver kit consists of four ceramic fuel "sensors" that are dropped into the gas tank and attached to the air cleaner and radiator hose.

In proof of concept testing, the California Environmental Engineering laboratory said its results verified with a high level of confidence the viability of Fuel Saver and indicated more dramatic improvements could be expected and achieved with time. "The device, as tested, provided results that are more dramatic than similar technologies previously evaluated," research director Joseph Jones wrote.

In a vehicle emissions test report conducted in October last year, Australia's Department of Transport and Regional Services found Fuel Saver led to "an increasing improvement in fuel economy and a reduction in vehicle tailpipe emissions. This included a significant reduction in greenhouse gases (28 per cent)," the report concluded.

The first link didn't work for me....

I would be tempted to call shenanigans on these folks, just on the basis of what they claim. There are tons of these types of "ideas" out there for improving fuel economy. Cow magnets, acetone, and others, and none of them work except to lighten your wallet.

The companies website is short on details. They have a video from a Chinese newscast (perhaps appropriately labelled TVBS).

In the off chance that there is something real, they will need to have an independent audit by a 3rd party to prove it, but if I were in a position to do such an audit, I would probably consider it a waste of my time.

Hmmm - you're right - it's completely disappeared from the SMH site.

Google News still has it (the link below doesn't work either, but it comes up in a Google News search for "moletech"), so I didn't imagine the article. Not sure why they took it down though...


SMH probably realized, too late, that they'd been scammed.

Nice to see the media setting it right so quickly.  The next step is to help them get it right the first time (Steorn, anyone?).

I come across this companies stand at the Batemans Bay caravan show, and they persuaded me to purchase a unit for my 7.3ltr diesel ford 250. I decided to trial it in my pick up and if successful i will look to my truck fleet.

Some three months later my F250 has increased fuel economy verying between 12.2% and 13.7% with noticably more torque. So now not so sceptical I looked to installing in my fleet, first I wanted to confirm their claims and asked for documnetations on DOTARS and the university report.

It all checked out, it is legitament. I have now started in Three trucks with a view to keep monitering the results before installing in the balance of my trucks. So far so good
when something seems to good to be true, there is usually a problem. So far no problems.

The Engadget link mentioned the California Environment Engineering Center for Environmental Research. Google couldn't find a match for this outfit with a redundant name. Sure smells like snake oil.

Try and Google California Environmental Engineering .
It does exist and it is one of the biggest testing facility's in the world.

Oddly, I too have a fuel saver to sell...


$1,500 bucks each.


Looks to be the exact same thing they had here in the US a few years ago.

They gave us some and we tried them in our motorcycle engines. We were never able to verify fuel savings.

As far as emissions the data was inconclusive, but we only used 5 gas infrareds for ECU mapping and not a full emissions lab. Maybe on that. The one thing that was very noticeable is that especially on some of our very high compression ratio engines the device seemed to prevent detonation, in the sense that we could run pump fuel with it when we had to run race fuel without it.

Perhaps one could make the case that given lesser tendency to detonate one could map the ignition with more advanced curves and gain some economy that way. Some of the more sophisticated closed loop ignition systems that use spark ionization as input like the very high end Bosch systems might do it for you.

I wouldn't expect it to work with no adjustments on less sophisticated systems. 


I did some research on this area when I was approached to endorse a similar device to my clients.

Always check this page first:
Gas Saving and Aftermarket Retrofit Device Evaluation Program

These devices are typically long on claims and short on actual results.

Peak Oil, Climate Change and Business
Free, Bi-Weekly Executive Briefing

From the Dresserator carburetor to magic polymerizers to magnets on fuel lines, all kinds of devices have been introduced. Their main claim to success has been in separating their customers from their money.

Carl Dresser (if memory serves) introduced his carb in the late 60s/early 70s and did manage to get Ford to look at it. They never committed obviously. Several car enthusiast magazines tried for some time to get access for evaluation purposes. Popular Mechanics I think it was finally got access around 1980 or so with very unsatisfactory results.

They installed one on several different engines and even after extensive tuning achieved negative results. In most cases mileage actually worsened with the miracle carb. This is the carb that popular mythology says 'was bought out by the oil industry' lol.

The auto companies have had incentive to do the best they can ala fuel mileage, most especially since the EPA and CAFE regs starting affecting business. I would hate to venture a guess as to just how much money has been thrown at it, billions surely.

New engines, intake and exhaust system design, combustion chamber design, fuel composition, you name it. Roller bearings in the valve train, 4 valve heads, computer controlled fuel injection with exhaust feedback, improvements to coefficient of drag, rolling resistance, weight savings with novel materials, all kinds of advances have been made.

There is no lack of trying in the industry to achieve the best possible fuel mileage. The basic formula hasn't changed a lot though in the last half century. A 3200 lb. car with a small block V8 in 1967 could reach 25 mpg on the highway if driven correctly. A new Corvette weighs roughly the same, has much better aero and can do only slightly better, rated at 29 mpg highway, probably more realistically 25 to 27.

We're up against physical limits here it would seem. Cut the weight drastically with much smaller cars, go bonkers on rolling resistance, aero and engine size and then teach people how to drive for mileage. Instant 50+ mpg.

All kinds of things out there to separate you from your money. Until outfits like this one come clean with details I remain skeptical.

Yeah, definite snake oil until proven otherwise.

I drive a diesel truck frequently towing a 10K lb trailer. Because of an fortunate accident, I had to replace the turbo intercooler with an aftermarket part. It had a larger cooling surface area and reduced back pressure. The results was a significant increase in fuel milage. By changing out the air filter to one with a larger suface area and replacing the exhaust system with a larger diameter pipe more improvement was attained. Finally after all that and some very careful record keeping I found that one of the biggest determinates of fuel milage was the road surface. A surface that had 3/4 inch and larger stone as the aggregate would knock the milage fifteen percent from that of a new smooth asphalt surface.

Many years ago, in a tongue-in-cheek manner, Mechanics Illustrated or one of the other similar magazines (don't remember which, but it was long before the internt) purchased a variety of gadgets that guaranteed increased mileage by various percentages and installed them all on the same car. The percentages added up to something like 115%.

As a result they had to stop the car every 200 miles to drain some of the gas out of the tank. "Just kidding" they said. "Milage actually fell off by 15%."

Ah yes, I recall that, just hilarious, lol.

Doomed to go through this again it looks like.

Lets look at the scale of problem:

Current energy usage at 15 trillion watts 86,400 seconds a day for 365.25 days means 475 million trillion joules per year.

Oil provides 33% of this by 31 billion barrels per year, 5,113 million joules per barrel.

Gas provides 24% of this by 3 trillion cubic meters per year, 38.5 million joules per cubic meter. Equivalent of 22.6 billion barrels of oil per year.

Coal provides 26% of this by 5.15 billion tons per year, 24,000 million joules per ton, equivalent of 24.18 billion barrels of oil per year.

Total energy usage from fossil fuels is equivalent of 77.78 billion barrels of oil comprising 83% of total energy.

The total human energy usage is equivalent of 93 billion barrels of oil per year.

For comparison, 6.5 billion humans each consuming 2500 calories per day use 24.93 million trillion joules of energy per year, 5.25% of total energy consumption.

If we want to use bio-fuels of any kind as energy source, we have to look at the fact that the most efficient plant in terms of energy is alfalfa which without fertilizer feed can grow 1600 kg per acre. If we do use fertilizers and pesticides we can boost the output to 4000 kg alfalfa per acre but then it would be energy sink. Assuming we can convert 100% of energy in alfalfa into biofuel it would be 1600 kg * 4000 Calories/kg * 4200 joules/Calorie equal to 26.88 billion joules/acre/yr or equivalent of 5.25 barrels of oil. So to get energy equivalent of 93 billion barrels of oil we have to keep aside 17.7 billion acres just for biofuel production. World's total land area is 37.5 billion acres out of which 15 billion acres produce some kind of food. That includes all forests, orchards, peats, meadows, farms etc. Remember that total food production of this planet is equal to the 2000 calories/day need of 15 billion people, 40% of this is utilized by humans and rest 60% is used by other 4 million species of plants, animals, birds and insects.

If we want to get energy directly by sunlight using photo voltaic cells we must note that per watt PV cell cost is atleast $3 and solar is at best 25% times working rest is when there is night, cloudy days, winter etc and atleast 20% of stored energy is lost in storage. So to have 15 trillion watts we have to have atleast an installation of 75 trillion watts of solar PV cells which cost is atleast $225 trillion dollars even if we ignore costs of installation, costs of conversion of current vehicle fleet to electricity etc.

World GDP is $40 trillion out of which $15 trillion is from industry.

I have a similar device to sell as well......a "special" tool to hold the mothballs while you drop them into your gas tank so you do not get stinky hands....$395.50 U.S.

The World turns, with or without U.S.

"Current energy usage at 15 trillion watts "

If you want to convert thermal units (e.g., BTU's) into electrical, you'll have to divide by about 3. For instance, the US uses 39 Quad BTU's to make 13 quad of electricity.

So, the world is about 5 TW.

For transportation the ratio would be about 6, as small ICE's aren't very efficient compared to electric motors.

Oh, and I think you've got the wrong post for biofuels.


Plus the fact that most PV is made from reject computer chips - more cost if you had to make them as a stand-alone product/industry.

From the Moletech website:

The Moletech Fuel Saver has the ability to change three areas within the spectrum of gasoline by absorbing the CH (Benzene) of saturated and unsaturated hydrocarbon. According to the university research papers, the ceramics absorb the thermal energy from their surrounding environment then release it in a specific wavelength, breaking the intermolecular van der Waals force (the force that binds molecules) between the gasoline molecules. This results in the change of aggregation of gasoline molecules from 'cluster' to 'single molecule'. This changes several properties of the gasoline, such as surface tension and flash point. The surface tension is decreased, resulting in better atomization (smaller droplets) of the fuel, which provides a greater surface area to make contact with air, leading to far greater fuel efficiency. This in turn increases horsepower, reduces fuel consumption, reduces carbon build-up and reduces toxic and greenhouse exhaust emissions.


Which university and what peer reviewed journal were they published in????

"Comments?" Hahahahahahahahaha!!!!! Thanks for the laugh, saved me the bother of looking. Stringing together a set of vaguely related large words into an incoherent paragraph is often an effective way of separating fools from their money. And energy issues seem to bring out limitless numbers of fools of every stripe.

Tha paragraph could have been written by Professor Irwin Cory. For those from down under he is a comedian who baffles with bullshit. http://irwincorey.org/

Ah, Prof. Irwin Corey. I really love that guy. The World's Foremost Authority. He has such a way with words.

Yes, better atomization should improve fuel economy and emissions.

Nothing new here. All kinds of things have been tried, Fords Twin Swirl Combustion Chamber, lasted maybe 2 years in production, etc.

After market devices again- fine screens placed between the carb baseplate and intake manifold, propellors placed similarly, you name it. A number of the 'mystery tech' gadgets claim the same.

So far the best improvement has been obtained from the more recent fuel injector nozzles with very small injection orifices placed just so to optimize mixture distribution within the combustion chamber.

Yea, I think I'll run out and buy one of each as gbenzon reminded us of. Then I can become a producer, lol.

gasoline is made up for the most part of iso-octane, with a few other molecules thrown in to achieve different qualities for the end product (organometallic anti-knock compounds, for example). iso-octane is not known for hydrogen bonding, presumably what the author implies when he talks about "clusters" becoming "single molecules". Supposedly the miracle cartridges are heated up by the gasoline (absorb thermal energy), and then emit vibrational energy at a specific wavelength which supposedly overcomes the van der Waals intermolecular forces between the iso-octane molecules. Checking with Margenau and Kestner, "Intermolecular Forces" pp.283-289, there appears to be no vibrational dependency which could be so exploited so as to lessen the intermolecular attractive forces which exist, since there would be no change in the bond polarizabilities. Even if there were a temporary change in the polarizability at the surface of the cartridge, thermal equilibration would bring back the clustering seen before interaction with the vibrational energies (if any) produced by the cartridge.

Adding utter flaming bullshit to your gas tank will not increase your gas mileage. These devices, every last damned one of them, no exceptions, are *all* utter flaming bullshit, and their advocates and shills should be sprayed with a thin layer of hot pine tar, coated from head to foot in chicken feathers, and driven away with suitable whip-cracking, fireworks, and ridicule.

Stream47, Gasoline is not "mostly" iso-octane, there usually is a good proportion of smaller molecules than octane and aromatics in it as well, hopefully not Benzene specifically but still aromatics that would show the intermolecular forces talked about. That being said I agree with your last paragraph - at least up to the bullshit part. Tarring and feathering maybe a little extreme.

Let's just think about it logically, if Shell, Chevron, BP or any of the big gasoline suppliers with their huge research budgets could come up with a patented way of increasing fuel economy don't you think the pick up in market share would be worth it?

Adding utter flaming bullshit to your gas tank

This could be called a biofuel thus being eligible for a subsidy, right?

"Adding utter flaming bullshit to your gas tank will ... "

If the bullshit is actually flaming, this could be very dangerous. You might not survive to conduct test of gas mileage ;-)

Yeah, a comment.

Breaking apart clusters of molecules means adding energy (raising them from a low-energy state to a higher-energy state).  The thermal energy claim appears impossible (2nd Law of thermodynamics) and there appears to be no other route for energy to get to the device.

I suspect that spectroscopy or other tests (evaporation temperature) could test these claims, if they still have any credibility.

Another one, from a company called Biosfuel, is Ecotube. This is from a company that, in 2005, claimed to have a technology called "enriched water", that allowed you to run your car on nothing more than water. A video of the TV article, about enriched water, is available on their website.

DANG!!! I just missed your post while I was snarking on about polywater. Plus ça change, plus c’est la même chose.

Maybe this is ceramically-induced polypetrol, with magical and undetectable transformation of aspects of molecular structure unknown to those stodgy chemists and physicists who waste years studying for degrees, publishing peer-reviewed papers, and so on. Such would follow naturally and inevitably in the discredited footsteps of past rubbish like polywater. Oh, no, wait a minute, we already have polypetrol, only we call it plastic. As this only makes the Fuel Saver kit even more unaccountably mysterious, it will necessarily be held to be ultimate truth by the conspiracy nutters on the 'internets'. </sarcanol>

These articles and adverts that are "short on details", written by egotistical but secretive folks who claim to be saving the world and refuse to say how, or by gullible, shiftless reporters who cannot be bothered to do even the most elementary fact-screening, nearly always arise out of fraud or self-delusion. With fuel saving devices, there's so much history of abject failure that it ought to compel great openness and verification before anyone bothers to pay attention. The furtive secrecy in this case is precisely the opposite, so I feel compelled to vote for fraud.

I do think lots of folks expect a cost-free solution to all our problems, a magic spell granting infinite population and economic growth at zero cost. Certainly that's what the candidates of both parties in the USA are selling, and certainly it's what these other fraudsters and dupes are also selling. So this sort of thing is probably a moneymaker for media firms. Sad, though, how it distracts from looking for real solutions.

The entertainment industry mythology about the car that runs on water, but was squashed by a nefarious group aligned to the automotive & oil industry is just too strong in the public imagination. I don't think we will ever see the end of this sort of thing. Those "how it works" quotes were great, reminds me of grade C scifi.

Hey don't bad mouth the enriched water. Down here in Texas they sell it in every petrol station or grocery. It comes in a long neck brown bottle along with a brown bag. It is then usually consumed on long commutes from the job. I have been buying it all my life. It seems to relax the leg used for the accelerator pedal and improves gas milage about 20%! However more than 1 bottle seems to have the opposite effect on MPH.

"It does rather sound like snake oil." Indeed. Perhaps it would be better to find a bit of evidence that it's anything else before putting it on the front page of TOD. A report from "California Environmental Engineering" does not mean much once you google them and find out they've reportedly found similarly amazing results for such things as magnets placed near the fuel line.

Tony's Guide to Fuel-Saving Gadgets

Even if this works it still presents the same problem as new oil
discoveries in only managing to offset depletion rates rather than
adding new barrels per day into the market mix.
India has just anounced the 1200 pounds sterling automobile.
This is great news for India and should see there major cities
grinding to a halt at rush hour within a couple of years.
As for petrol consumption - I would think that if every car on the
planet was fitted with working technology that gave a 20% increase
in fuel efficiency tomorrow ... the savings would be wiped out in a
year or two with through the steady increase in the number of cars
on the road.


I agree, I know weekends can be a little quiet for news but with all the snarking we do around hear about journalist not fact checking, I think we could do a little better research ourselves before stories make it to the front page. This looks like it belongs on Drumbeat at best.

I originally just posted it to TOD ANZ as I thought it would provide some amusement for us locals.

I imagine Prof G put it on the front page because there were no other stories in the queue for the day - personally I think it generated some interesting comments - but it wasn't intended by me to be given any prominence, and nor was I promoting the idea as real...

There is some value in debunking these sorts of claims as it means when people come across these claims in supposedly reputable periodicals they can find out what the real story is when they do some searching. Otherwise all they can find is regurgitated marketing.

I also have a foolproof gas saver design that I give away for nothing. It is a small piece of notched wood with a tie wrap that attaches to the underside of the gas pedal. It's called a poor mans governor.

You should rename it as a 'Clipped Signal Mode Restricted Amplitude Governer' and make it out of brushed chrome, you could sell hundreds at least.

Stoichiometric of the air/hydrocarbon, is way off. With a large excess of Gas to air. This is because the Gas burns rather than explodes, as it would at 1:1. If some means could be found to power autos with hydrocarbons at 1:1 rather than the present ratio this would be a help.

If some means could be found to power autos with hydrocarbons at 1:1 rather than the present ratio this would be a help.

Newer cars have an oxygen sensor which implements your suggestion.

The car's computer constantly monitors the oxygen content of the exhaust manifold and constantly adjusts the fuel-air mixture via the injectors. This is also recorded in the OBD-II (On-Board Diagnostics version 2) as "long term fuel trim" and "short term fuel trim".

These can be read out by a scan tool, and these trim values are often useful in diagnosing fuel mixture problems, such as faulty injectors or oxygen sensors.

Now, my old Toyota. Yup - just like you say, I always run it lean. Its mechanically carbureted, and lacks the precision of computer driven fuel injection.

I'd rather toss unburned air through the combustion cylinder than unburned gas. I tune for minimal HC (hydrocarbon) and CO (carbon monoxide), but stop shy of releasing too much NOx (nitrogen oxides).

If some means could be found to power autos with hydrocarbons at 1:1 rather than the present ratio this would be a help.

Newer cars have an oxygen sensor which implements your suggestion.

The car's computer constantly monitors the oxygen content of the exhaust manifold and constantly adjusts the fuel-air mixture via the injectors. This is also recorded in the OBD-II (On-Board Diagnostics version 2) as "long term fuel trim" and "short term fuel trim".

These can be read out by a scan tool, and these trim values are often useful in diagnosing fuel mixture problems, such as faulty injectors or oxygen sensors.

Now, my old Toyota. Yup - just like you say, I always run it lean. Its mechanically carbureted, and lacks the precision of computer driven fuel injection.

I'd rather toss unburned air through the combustion cylinder than unburned gas. I tune for minimal HC (hydrocarbon) and CO (carbon monoxide), but stop shy of releasing too much NOx (nitrogen oxides).

If some means could be found to power autos with hydrocarbons at 1:1 rather than the present ratio this would be a help.

Newer cars have an oxygen sensor which implements your suggestion.

The car's computer constantly monitors the oxygen content of the exhaust manifold and constantly adjusts the fuel-air mixture via the injectors. This is also recorded in the OBD-II (On-Board Diagnostics version 2) as "long term fuel trim" and "short term fuel trim".

These can be read out by a scan tool, and these trim values are often useful in diagnosing fuel mixture problems, such as faulty injectors or oxygen sensors.

Now, my old Toyota. Yup - just like you say, I always run it lean. Its mechanically carbureted, and lacks the precision of computer driven fuel injection.

I'd rather toss unburned air through the combustion cylinder than unburned gas. I tune for minimal HC (hydrocarbon) and CO (carbon monoxide), but stop shy of releasing too much NOx (nitrogen oxides).

Quick question from a non-engineer: Why isn't compression ignition used with gasoline? On the face of it, with the gasoline injected like normal diesel fuel at TDC (thereby avoiding pre-ignition), one could use far higher compression ratios and presumably achieve similar efficiency to diesel fuel.

The "oiliness" of diesel is needed to lubricate the injector pumps etc in a normal diesel engine. I have been tempted to trying running my diesel VW Golf on gasoline with some biodiesel mixed in to provide lubricity, but am worried that I will damage the engine. I know for instance that you can mix gasoline at up to 50% with no ill effects in diesel cars. (If you make a mistake filling it up - don't panic, try and siphon/drain some/most of it off and top it off with diesel).

Why? - it is apparent that diesel fuel is going to be in short supply before gasoline. It is a "vital" fuel, where as gasoline is far more discretionary.

Historically, the gasoline engine came first, and made use of what was then a waste product of the kerosene refining process. Gasoline was hence very cheap.

The diesel engine was developed (by Diesel) in a search for increased efficiency, and did indeed prove to be more efficient than the gasoline engine.


Diesel engines knock. This is okay: They are designed for it. But this makes them heavier than an equivalent gasoline engine, for they have to be sturdier.

Also, the Diesel design is inherently more expensive to build; gasoline engines are cheap to make.

Diesel fuel was cheap at the time the diesel engine was developed. The success of the diesel engine means that diesel fuel is no longer so cheap. But it still contains more energy per gallon than gasoline, so only rarely is gasoline really "cheaper" than diesel. Retrofitting your diesel engine to accept gasoline probably does not make sense.

The diesel engine's high efficiency is obtained over a relatively narrow range of rpm. It likes to run at a particular speed. This in turn means more gears are needed in the transmission. This adds to cost and reduces convenience. In contrast, a gasoline engine runs well over a broader range of rpm, making it preferable for a "fun" vehicle--like a car--where "performance," not efficiency, is the requisite virtue.

There are three main types of ICE engine:
The normal gasoline engine is spark-ignition, the fuel is injected before compression, and has time to mix before ignition.
A spark ignites the mixture near TDC. Because of the danger of pre-ignition "knocking" compression ratio is limited, which limits efficiency.
The second kind you mention is diesel, the compression is sufficient to cause ignition, and the fuel is injected near TDC. Higher efficiency, but because there is no time for the fuel and air to mix before ignition, it is hard to control emissions.
The holy grail is called homogeneous charge compression ignition HCCI. Here the fuel is injected early on like the spark ignition engine, but the compression causes the mixture to ignite near TDC. This combines the efficiency of diesel with the low emissions of spark ignition. It is difficult to control well. You need ignition near TDC, a little off on the operating parameters and you could ignite too early, or not at all. This is hard to do over a range of operating conditions, but might be doable with modern computer controls.

Fuel air mixture, is I think not too far from stociometric ratio in modern engines. I think our polution control means we cycle
our engines between slightly rich in fuel, and slightly rich in air. The first generates hydrocarbon emissions, and the second nitrogen oxides. By cycling some pollutants can be collected in the catalytic converter, then burned off with the next change of cycle.

Why isn't compression ignition used with gasoline?

Two major reasons:

  1. CI of a pre-mixed air/fuel charge means the charge essentially detonates.  This requires much greater strength of the engine, as well as creating a lot of noise.
  2. CI of a pre-mixed charge makes it very difficult to control the ignition timing.  If you ignite too soon, you complete the compression stroke against a fully-burned mixture and have enormous stresses; too late means no ignition at all (miss).

There is work being done now on HCCI (Homogeneous Charge Compression Ignition) engines using gasoline fuel.  They only operate in HCCI mode at low to moderate load, and use CI to ignite very lean mixtures which could not be fired with a spark plug.  The ability to run ultra-lean allows the engine to be run unthrottled (like a diesel) at low load, reducing pumping losses and increasing efficiency.  The auto-ignition is controlled by variable exhaust valve timing to retain hot exhaust gas to pre-heat the charge.  At high load the engines go back to spark ignition.  None of this would be feasible without very advanced electronic controls.

On the face of it, with the gasoline injected like normal diesel fuel at TDC (thereby avoiding pre-ignition), one could use far higher compression ratios and presumably achieve similar efficiency to diesel fuel.

The optimal compression ratio for best efficiency is around 16:1.  Diesels require compression ratios of 18+:1 to achieve reliable ignition, and even then they need fuel with a much higher cetane ratio than gasoline.

Great response Engineer-poet. Thanks. I learn so much at TOD, I am humbled.

On a different and sadder note I see that Oilman Bob died. Very sad. He was a great contributor.

I installed an msd ignition on my 1982 VW HOT rabbit [1989 Fox 1.8 liter engine, 5 speed, headers and 2 inch Tectonics exhaust] and logged mileage before and after, while having lots of fun posting.

I got crisper starts, maybe a bit more power, but advertised gas mileage improvement as a result of the msd ignition is questionable.

But installation of exhaust headers caused the emissions to drop by about 90% and added LOTS of horsepower and perhaps increased mileage a bit. The 2 inch tectonics exhaust helped too.

Grey rabbit has had problems for about a year and one half.

Next step is to try a "new" fuel pump.

Then pull the head if the problem is not fixed.

But I've been too busy with other projects to devote time to try to figure out what is wrong with grey rabbit.

I liked the comment about critical peer review.

Publish or polish.

:)s from us guys

Experimenting with target="_blank"

Us seniors, 45 days younger than saddam, deserve a senior citizen posting mistakes [misteaks?]


I had an '86 Jetta. Gearing is the way to get mileage out of that engine. Find an old quantum with a manual trans. It had a REALLY tall 5th gear, which will fit on any 8v trans. I was able to pull 38-41 mpgs with that, a techtonics exhaust, and a the VW alcohol cam (techtonics sells it).

Got over 350,000 merciless miles out of the engine. Got rid of it due to body rust.

Somewhere in the estate of my friend/ex-employer/Ex-prof there was a 'here's how to save fuel' book from the 1970's. I should dig that book out....

About the only 'change' I can think of that did work was he use of water mist into the air intake. Had to do with the change in volume in the cylinder is greater then the effect of heat, if I remember what was said.

VW microbus owner told me sniffing water works to improve mileage.


Funny thing about the term "snake oil": Originally the term for the patent medicine ingredient was "Seneca oil" after the Seneca indians of Western Pennsylvania. They collected this oil by skimming it off the surfaces of ponds. It was crude oil.

Think of it - the entire U.S. economy runs on snake oil. Use of the substance is promoted by snake oil salesmen.

But you already knew this.

And yet there are those who will try to sell us snake oil in order that we might use less snake oil. The snake bites its own tail.


Check Wikipedia. The "Seneca Oil" option receives very little mention compared to the other explanation that it was originally the oil from the "Chinese water snake", known to be high in omega 3 oils (especially EPA),and long used in traditional Chinese medicine. Fish oil is more often used nowadays as a source of EPA.

The modification of gasoline so as to reduce surface tension isn't anything new.

No one needs to spend hundreds for that.

Lots of people mess around with acetone to achieve the same thing.


Surface tension?! No. Acetone isn't magic. It just has a high octane (~115), and can be used to raise the octane of regular gas to high-test. Street racers have been doing this for years to run big turbos on higer compression engines without having to spend big bucks on race fuel.

It won't help your gas mileage, unless you are running the wrong octane fuel to begin with. Low octane fuels in high compression engines will make the control unit pull back the timing, preventing knocking but reducing power and gas mileage.

For those who are seriously interested in improving fuel economy, here are some solutions that are known to work but not widely used:

a) Direct Gasoline Injection

Improves combustion efficiency - savings of around 15% compared to conventional Multipoint Fuel Injection (See: http://www.hitachi.co.jp/Div/apd/en/products/ems/ems_001.html)

b) Hotel Load Reduction

The hotel load of vehicles (Air conditioning, entertainment, etc. have steadily risen. Reducing the load by improving insulation / heat unwanted gain / loss in the passenger cabin, and improving the efficiency of electrical appliances can potentially save a few % of fuel. Right now, the electrical load is 500-700w and rising by 150w or so a year. Widespread use of LEDs, HID lighting, less power hungry computers and entertainment systems, elimination of marginally useful electrical gadgets like electrically heated seats, etc. can all add up.

c) Shed the Weight

Vehicles have steadily become heavier and bigger. The regulatory environment gives no bonus points for vehicles that are lighter and more efficient to move around, and also, less of a mass to bring to an abrupt stop in an accident.

Every kg of mass shed in the vehicle create a positive feed forward for a lesser sized engine, etc.

The Rocky Mountain Institute did a study several years back of how a car can be far more efficient manufactured out of light weight (carbon fiber composite) materials.

Likewise, shouldn't consumers have a choice over whether to have their cars equipped with 100lbs of airbags and accessories when plain old fashioned seat belts provide nearly the same benefit?

The amazing thing is how the auto industry, whose livelihood require the existence of affordable liquid fuel, have not embraced these nearly no brainer 'development' as opposed to 'research' projects.

A top-to-bottom review of all the rules and regulations governing vehicles and reassessment of its impact on innovation and cost / benefits in light of fuel costs 3X to 10X today's should be done by the US, leading to the creation of an alternative classification of vehicles "super efficient" that are exempt from most 'safety', 'emissions' and other rules and for, say, 20 years to encourage innovation.

At the same time, these new "super efficient" vehicles need to be shielded from liability lawsuits (i.e. a maximum legal award of $100k per vehicle for any reason) for a period of 20 years while the vehicles are in the 'experimental' category, then followed by a period of transition where the liability cap is gradually raised in the next 20.

Unless something like this is done, the center of high efficiency auto / transportation innovation is going to go to places where the innovation can happen without a lot of rules --- like China.

I would at the outset, set the bar for 'high efficiency' at 120mpg or equivalent (for non-gasoline fueled vehicles) for the first 15 years of the program.

I like this forum due to the seemingly intelligent commentary...but I think on the subject of mileage saving devices I'm seeing mostly the same derision I might see on most average forums where the subject might be appropriate.

I've "studied" the mpg subject for the last 2-3 years and have managed to improve mpg with 2 vehicles by around 30% on my own.

Yes there are a lot of snake oil gadgets out there and improving mpg is not that easy. You need to keep an open mind and do your own actual research. Usually just installing one device results in little gain.

Here is a site that might rock your boat a little:


I'm speaking of the HAFC...not the PICC.

I know (at least online) some of the people involved with training for the HAFC installation...and though I don't have direct experience with it...I do believe it is the real thing.

The HAFC is a SYSTEM...that is...it uses quite a few mpg boosting techniques together.

There are also other "systems" available such as these:



* I'm not promoting these sites or systems...posted as FYI only.

Oh please. Magnets to "ionize" the fuel and "break it down into tiny sized molecules". Pure snake oil. Fuel preheating often causes detonation when you run on gasoline. On diesel or ethanol it may be another matter, but this supossedly was for gasoline.

And then the unit to produce hydrogen gas. You know what kind of losses you have when converting water to hydrogen with electricity, right? Where does the electricity come from? Right.

The only thing that might reduce fuel consumption is the "computer". Probably leans out the fuel mixture to dangeorus levels by simply obscuring the output from the oxygen-sensor.

Another "system" for your perusal:


"Evaporation for Gasoline Engines. The SAE document number is 860248. This paper is available from SAE International for $14.00 through their website at sae.org. The paper describes how heat is used to help gasoline evaporate before it enters the intake manifold where the warmer fuel enhances engine efficiency and mileage. Naturally Ford is doing the opposite of what the paper suggests by introducing COLD air and fuel into its new engines. All American cars employ cold air and cold fuel. It is therefore obvious that Ford is deliberate in its attempts to damage fuel efficiency in its cars--disregarding such important papers as this one. We ask you to check it out for yourself. An ex-Ford engineer pointed it out to us recently. Look at the air filter box on our 1995 Mazda 3.2-liter pickup (a Ford vehicle). We blocked off the cold air from the fenderwell. We bored numerous 1-1/4 holes in the air box so the air filter would receive WARM air from INSIDE the engine compartment. This Mazda gets far better mileage and power today. It used to be quite gutless at only 13.4 MPG. Now the pickup zooms along nicely at 40 to 44 MPG with power to spare. A 1996 Olds has the same Fog units and FeverBuster and the the same holes in its air box and averages 42 to 46 MPG. Both cars have gasoline without ethanol and use the GammaFuel-G additive. They are an absolute joy to drive."

False. Why? Cold air have more oxygen -> more power. Wonder why turbo-charged engines use intercoolers to cool the intake air? For old carburated gasoline engines it is recommended to warm the intake air when it is well below freezing, not otherwise. Modern engines with fuel injection in cars that are marketed in places that have extreme cold in winter often have thermostat regulated intake air. You don't get anything from heating the intake air over about 20 degrees Celcius (~69F) on a gasoline engine. I know, 'cause I've done the testing on my own cars. One is a old carburated one, the other is a newer with fuel injection. When it is really cold in winter (once -40F) I gain some milage by keeping the intake air above freezing. Still lose milage due to increased aerodynamic drag (again, cold air is more dense) and studded winter tyres. I've never owned a Ford though. Maybe Ford sells really lousy cars these days. Might explain their heavy losses?

Read up on atomisation/vaporation:

According to this AFS chart, less than 70% of the oil is used for transportation and of that less than 40% is used for personal cars.
That says that you could take 10% of the cars off the road and still only reduce our oil consumption less than 3%. Big, big problem.