<-- The magnet expert.
In opposition to another show funded by advertising (though not as bad) I made my own magnetic fuel saver.
I'm sorry to inform you that it's not going to work BlueFront. The idea is sound, however you need more powerful magnets.
Someone mentioned that there was a company which had one the size of a fuel filter or oil filter. That's correct, but as far as I know that company is no longer in business. They used 3 large neodymium magnets in a triangular configuration, and it cost close to $300. The biggest problem was that it was sold in a MLM framework, so most people didn't trust it. One of our newspeople here in Memphis found a person who'd been keeping track of his FE since he bought his Toyota 4 Runner. They also took it to a dyno. The dyno showed no increase in hp, but did show leaner fuel trim, and lower emissions. Using division at the pump, they noticed a 5-6 mpg increase from the lowest mileage he recorded in the life of the truck. The video used to be online, but I can't find it now. If you want to search try Channel 3 news, Andy Wise, Memphis, fuel saver. Maybe your google is better than mine.
I tried it myself with N38SH magnets made for temps up to 300F. That is the drawback of Neo Magnets: they lose magnetic potential when exposed to heat above 160F, special coatings can help, but these are difficult to locate. I can no longer find the ones I used before, and for my latest project have decided to use Metal Shield and relocating the magnet structure to a less high heat location under the hood.
Now, the magnets I used on the D20 with the stock fuel line that runs right over the exhaust manifold lasted for approx 6 months. I noticed a tad increase in power that could've been in my mind, and 3-4 mpg difference at the pump. The idle was much better also (more steady)- but that might just be my car. After those magnets died, it's been over a year before I'm going to try again- I just haven't had the time. Keep in mind that although these magnets are dead, they will still lift 20 lbs each. You need extremely powerful neo magnets (sadly SmCO magnets aren't powerful enough) held together in a structure built out of aluminum or SS to go around the fuel line with the polarity pointing towards (repelling) the same.
This is no sissy project, if you put 4 of the magnets I use on one side of your hand, and 4 on the other side- it would crush your bones. You cannot pull these magnets straight apart from each other, they must be slid until there is not much magnetic surface touching, and you must be careful of anything magnetic or ferrous nearby. One of the older magnets shattered when I got it within a foot of a 1 1/8" wrench which flew up to the magnet- kablam. The shards could've put my eye out, so be careful.
If anyone wants to know how to make the calculations, what to do and where to order, contact me and I'll share the information. I can't make them for you since that would be against FF rules, but the math is simple, and if you use aluminum- it's easy to cut and find at hardware stores. I do have pics too, but no time to post at this moment.
BTW, I tried this on my van with the magnets mounted approx 6' away from the engine before the fuel filter (only place I could do it without moving the fuel lines). I noticed a 4-5 mpg increase in fuel economy, but unfortunately, the van has developed a head gasket or intake manifold gasket leak due to overheating when a screw banged around inside my fan shroud during spring. I'm not even sure if those figures are accurate as a result of the coolant leak. The Focus will come soon- too many other projects at the moment.
Sorry BlueFront, I wished you would've asked me first. There is real tech behind some of the crap tech out there, but you have to search long and hard to find the pertinent information. No magnetic fuel savers for sale are powerful enough to do the trick, you must build your own, and for a D powered Focus, I highly suggest relocating the fuel line away from the exhaust- but I'm not completely sure where yet since you should stay a good distance from electronics.