Years ago, I remember seeing ads for a new type of spark plug-they were touted as lasting forever, and never fouling up. They used a center electrode which was surrounded by an insulator, with an outer ring-the idea was that the spark would be able to jump the gap, around the whole circumference-instead of a standard plug, where there is an electrode attached to the rim.
I never knew anyone who bought these things-has anyone any expereince with them? Did the work as advertised?
Apparently not, as they don’t seem to be sold any more.
If anything, what you’ve described almost sounds like plugs for Mazda’s Wankel engines. These plugs don’t have the traditional single hooked side electrode sticking out, where it would interfere with the rotor.
These guys still make them.
It’s unclear whether they offer any advantages over conventional plugs.
I’ve seen some good reviews about these.
E-3 sparkplugs.
They call it an edge to edge electrode.
I guess I’m not sure about this particular variation, but “performance” spark plugs in general don’t do squat on an otherwise stock engine. All a spark plug has to do is ignite the fuel-air mixture and either it does or it doesn’t, and the stock spark plug does. As for longevity, platinum plugs last forever for all practical purposes (I’m already uncomfortable leaving a plug in my cylinder head that long), and when was the last time you had a plug foul up?
Aviation spark plugs use 2 posts that surround the electrode with 2 half circles of surface.
I don’t know if an outer ring is such a good idea as it precludes the possibility of setting your own spark gap distance, plus high-tension sparks like to form on the pointiest end of a conductor, where the charge density is the greatest. But they might last longer, depending on the ignition system. On a normal single-earth-electrode plug the the spark will jump between the rim edge of the centre electrode and (usually) the one of the two closest corners of the earth electrode. An earth ring with pointy teeth might work well, but not a smooth ring (need to see a pic reallyto judge properly).
I’ve used twin and triple earth electrode plugs from NGK and Bosch, both respected companies, in a stock engine, and they do make a small positive difference. With these types the spark has 2 or 3 paths (depending on the number of earth electrodes), and even though there will only ever be one spark at any one time, having the option does seem to make a difference. The spark will always follow the path of least resistance, which in the environment of a compressed fuel/air mix in a combustion chamber will be the path of greatest ionisation. Maybe that helps keep the timing tight (fewer small retardations due to slightly late sparks), maybe the initial flame front is beefier as the spark finds the path with the best fuel/air mix (the mix won’t be completely homogeneous and there will be pockets inside the cyclinder that will ignite more readily). Whatever the mechanism, they do work.
A positive polarity spark will wear the earth electrode out faster than the centre electrode, so vehicles that have such a system will enjoy longer life from dual or triple earth-electrode plugs, and probably also the odd ring earth of Ralph124’s OP. They would have no benefit with a negative polarity spark, as this wears the centre electrode more, and there’s only one centre electrode. Some systems have half the plugs firing with a positive polarity and half with negative - on these rotating the plugs like tyres (+ve to -ve and vice-versa) would stretch out the lifetime a bit.
Magiver’s link to aviation plugs didn’t work for me (needs a login profile), so I looked these up. The ones on this page are dual-electrode types, except sideways on, I suppose to obtain a higher compression ratio by enabling a smaller gap between the piston crown and cylinder head at TDC.
Those E3 plugs (RedSwinglineOne’s link) look interesting, and appear to offer a combination of two spark paths plus some directional focusing of the flame front. Looks like they come with a fixed gap though. Shame I’ve got a diesel now, or I’d give 'em a shot.
They use them on some two-cycle outboards.
Probably not.
This has been my observation as well. Every so often some new revolutionary, my God! this is the greatest thing ever invented spark plug is touted heavily in a flurry of advertisements. The ads are always constructed in the “how to sell crap that doesn’t work” mold, and within a few months the item is never heard from again.
ETA: Which isn’t to say that some of these designs aren’t used. It’s just that when they’re made by established plug manufacturers and used/recommended by vehicle manufacturers, they aren’t pushed strongly at do-it-yourselfers as the be-all end-all of spark plugs.
Anything that improved engine efficiency, emissions or performance (as these things tend to claim) in a cost-effective way and without major drawbacks, would be used by the car manufacturers. They wouldn’t be peddling shit in the back of magazines. There is so much money in car efficiency and such that if someone made something cheap that helped, it would be in every new car and the inventor would be rich. That’s how you know gadgets like the ‘vortex’ air intakes are bullshit. There are some exceptions, but they involve tradeoffs. There are modifications that can improve power, for example, but you will suffer in gas milage, emissions, or engine longevity.
The ring electrode seems like a bad idea to me in general… It looks like a great surface for conductive carbon to build up on, effectively reducing the spark.
I did switch last year from the cheap, manufacturer recommended plugs in my boat and jet-ski to iridium, and noticed no performance gain at all. The only difference, was markedly less carbonization of the plug tips, which I attribute to the iridium plugs having a very VERY fine wire center electrode. They are still in there, but I’ll be switching back to the stock plugs this year when I get around to changing them.
You should have noticed a performance increase from your wallet being that much lighter after buying the iridium plugs.
Aye, I did. It wasn’t onerous, but IIRC, the iridium’s were 7-8$ each, and the stocks are about $3. I was mostly looking for a good solution to fouling, but /shrug. A new set of 12 plugs each year for the boat and ski is a drop in the bucket compared to fuel (as an aside, I really want to pit the new CARB standard gas cans, and the state that fostered them).
I also did try the ‘multi-ground’ tip type plugs, again, no noticeable gain, and on inspection, the arc always favored one ground electrode.
Oh geez, those horrid things followed me! IME, they cause spills rather than prevent them.