[Pumblechook (OP)]

You can buy magnets to attached to your car's fuel line. What is this supposed to achieve?

[graham.d]

It sounds like part of a song that a technological Mary Poppins might sing :-) It doesn't scan well though.

Not much idea what this is about. It could trap some contamination, mainly iron, that could have got into poorly kept fuel to stop it blocking injectors (not many carburettors around these days).

[Pumblechook (OP)]

If you Google on it you will find loads of companies flogging fuel line magnets which they claim improves fuel efficiency and/or power output.   Some folks seem convinced that they work.   A fool and his money.......

There are loads of other devices on sale as well which claim similar results.

[graham.d]

Hmm. I would say that they don't work. I think Ford and GM would be very interested if they did and I don't see them fitted to new vehicles.

[Pumblechook (OP)]

Somebody pointed out that many fuel lines are made of steel so the magnetic flux wouldn't even reach the fuel. 

[graham.d]

Actually the flux will penetrate. It is not like an electric field and a Faraday cage. It is quite hard to block a magnetic field.

[Pumblechook (OP)]

NO.   The lines of flux will NOT pass through the steel tube.  There will be no flux inside.  I have just tried it and a magnet on the outside has no effect on a penny on the inside whereas with a plastic tube the penny moves along the tube with the magnet. 

[graham.d]

I am not sure why your experiment turned out as it did, but I admire your investigative attempt.

Have a look at :

http://www.physlink.com/education/askexperts/ae512.cfm

The metal tubing may attenuate the field, depending on the material, but not block it. People used to use something called mu-metal to try to block magnetic fields. It is an alloy which has a high magnetic permeability and is somewhat successful in blocking magnetic fields.

[Pumblechook (OP)]

"" I am not sure why your experiment turned out as it did, but I admire your investigative attempt."""



It proved my point.  You try it.    There might be a very very slight field left but so weak to have no effect on the fuel which doesn't react to a magnetic field anyway.. It is nonsense.


From your own link..........

If you want to block out magnetic "force," your best bet is to re-route magnetic field lines (lines of magnetic flux) around the object that is sensitive to those lines. Do this by shielding the object in a material with a much higher magnetic permeability of the surrounding materials.

That is what the steel tube does. 

[graham.d]

You are quite right, but steels have to be made specially to have a high permeability and stainless steel has a permeability quite close to 1 (i.e. that of fee space). Ordinary steel tubing will attenuate the magnetic field, and do so by effectively concetrating the field lines in the casing, but there will still be a component inside. If a rare earth magnet were used they would have quite a high field strength and a fuel tube is only a few millimeters in diameter so I would expect to still have a high field inside the tube. Nonetheless, I agree with you that the concept of it affecting the fuel is nonsense.

[lyner]

In terms of the magnetic circuit, the 'hi mu' material acts like a low resistance (reluctance) path in parallel with your fuel.
These fuel saving ideas have been with us since the first motor cars, I think.
Magnets do work in reducing the effect of limescale in water systems, though- but this is an ionic thing rather than covalent. My limescale has not been reduced in quantity but it is different - softer - and doesn't build up in the same way. (Not my personal tubing, you understand - the pipes in my house)

[turnipsock]

This is the first I have heard of this, what is the theory behind this?

A better fuel saving idea would be a magnetic front bumber, this would act like an invisable tow rope to the car (or lorry) in front.

I can't see how a magnet would affect the amount fuel an engine needs to provide a certain output. Even if it did, would a stronger magnet make a bigger difference?

If I attached a magnet to a beer tap, what effect would this have?

[Bored chemist]

"what is the theory behind this?"
I have a theory that there's one born every minute.
There simply is no basis in any curent theory for this idea of improving engine efficiency or power. There's also no evidence for it in practice.
The same goes for those "magnetic" pipe descalers.

[Pumblechook (OP)]

Must be quite a few born every minute.  The are lots of firms flogging these magnet things and other devices.

Just one.....


""""The Ethos MAXPower Fuel Saving Unit is an incredibly powerful, heavy duty, fuel conditioner that simply attaches to your vehicle's fuel line, without the need for any tools or pipe cutting, and increases your miles per gallon (m.p.g. & l/100Km) by an incredible 20% and more!

The Ethos MAXPower Fuel Saving Unit is powered by a pair of Neodymium super magnets which deliver an incredible force, powerful enough to fracture the hydrocarbon chains in the passing fuel.

A certified U.S. Environmental Protection Agency (EPA) laboratory recently completed tests on the new Ethos MAXPower Fuel Units. The results were astounding!"""""


Interesting that the EPA itself have tested about 100 fuel saving devices including fuel line magnets and concluded most have no effect at all. Some did actually work (not magnets) but the improvement was only slight. Quite a few had negative effects and some could damage an engine and may even be dangerous.


 
Gas Saving and Emission Reduction Devices Evaluation

http://www.epa.gov/otaq/consumer/reports.htm

[Pumblechook (OP)]

From Popular Mechanics.....

MIRACLE MAGNETS
There are dozens of fuel-line magnets on the market. We tested two. They all make similar claims: substantial improvements in fuel economy, reduced emissions and increased horsepower.

According to the people selling these devices, as gasoline flows past the magnet, the magnetic field will "break apart clusters of fuel molecules so gas burns more efficiently." Problem: Gasoline molecules aren't magnetic, not at all. But wait, there's more. If the fuel line is steel, as many are, the lines of magnetic flux will follow the fuel-line walls instead of passing through the fuel.

THE DYNO SAYS: As we suspected, neither device had any significant effect on performance or economy.

------

Looking For A Miracle: We Test Automotive 'Fuel Savers'


http://www.popularmechanics.com/automotive/new_cars/1802932.html


Tests were done at  the Universal Technical Institute, a large training facility for automotive technicians, in Houston, Texas.

http://www.uti.edu/

[Pumblechook (OP)]

Some devices actually had a negative effect...

------------

VORTEX GENERATORS


THE DYNO SAYS: Both devices reduced peak horsepower by more than 10 percent. The Intake Twister increased fuel consumption by about 20 percent; the TornadoFuelSaver provided no significant change.

4 pages......


http://www.popularmechanics.com/automotive/new_cars/1802932.html

[Pumblechook (OP)]

ENGINE IONIZER

THE DYNO SAYS: The truck we tested showed about a 15-hp loss with the Ionizer. About 10 miles into our economy test, the left bank of rubber capacitor blocks started to melt and sag onto the red-hot exhaust manifold. When smoke started to fill the dyno room, we interrupted the test and redressed the wires and capacitor blocks more securely. But when one on the right bank liquefied and dripped onto the manifold, we had flames a good 2 ft. tall, requiring the use of a 20-pound fire extinguisher.

http://www.popularmechanics.com/automotive/new_cars/1802932.html

[Kryptid]

Mythbusters tested such a device. It didn't work.

[Pumblechook (OP)]

Strange thing is many people really do think these things work.   

I kid you not.  Some years back a pal of a pal was convinced that a magnet on the battery lead and I think it had to be the negative one was saving him fuel.

[lyner]

"what is the theory behind this?"
. . . .  .
The same goes for those "magnetic" pipe descalers.

There is a definite difference in the form of the limescale but not the quantity. I have personal observation to back this up and I know of at least one more quantitative study which confirmed this.