Great study on spark plugs and # of electrodes

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That IS interesting

(Rather badly written, presumably by non-native speakers, and you have to really dig for the meaning of the various acronyms, but the technical conclusion looks clear enough.)

Next time I'm buying plugs, I'll see if I can find any without ground electrodes.

Or should I just take a hacksaw to my existing ones?
 
Surface gapped plugs (no ground electrode) were in my Mercury outboard back in the 60's guys. Nuttin' new there.

Ever see a JC Whitney "Fire Injector" plug?

Mfgrs are working on plasma plugs for the next big leap in ignition. But with all the variations in combustion chamber designs and strategies for flow and turbulence therein the plug has become less important these days for some cars than others.

This info is, as usual, wildly engine specific/duty cycle specific/fuel type specific/etc. and may not apply to your particular car at all. As we all know, some cars are SUPER sensitive to plug type and others will run on anything...
 
Apparently called surface discharge plugs, and originally developed for rotary engines.

http://en.wikipedia.org/wiki/Spark_plug#Surface-discharge_spark_plug

BUT they have a restricted heat range, and are predictably fairly pricy, so probably not going to be a viable option for me. Interesting though.

http://www.eng-tips.com/viewthread.cfm?qid=204582

NGK seem to be nost often mentioned as a source, but a biker magazine in a local yoof cafe/restaurant I was in at lunchtime had an ad (in Chinese) for what looked like a local version. Most local bikes are single-cylinder so you'd only need to buy one.

The Wikipedia article also mentions "indexing" conventional spark plugs to the optimal orientation in the combustion chamber. (so the ground electrode doesn't quench the flame.) which I don't remember thinking or hearing of before.

Great! A whole new area of obsession, and that's potentially FREE!
 
If anyone feels like developing a fuel injection kit that injects via a spark-plug port adapter and can be retrofitted to a 2-stroke motorcycle, there'd be quite a few customers for it in SE Asia.

Spose the plug area might get a bit crowded though.
 
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Surface gap plugs have no heat range, just a gap. I had a motorcycle that originally speced surface gap plugs...it ran ok, but was very hard to start, but there were other issues that were contributing to that. I stuck with standard plugs for it.
 
Plug wasn't really a surface gap, looked more like it just had the electrodes chopped off, and was jumping from the tower to the side shell...not sure if it could increase the spark power as suggested, as with that arc length, it would be drawing pretty thin.

The picture of the three electrode plug gave me the giggles.
 
Originally Posted By: Ducked
Great! A whole new area of obsession, and that's potentially FREE!


Can go beserk with a pair of sidecutters, a points file, and some plugs, creating better geometries etc.

My favourite was on my distributed vehicles, where I made a spark gap capacitor for the coil lead, with two concentric pieces of brass tube, held apart, and the lead broken, feeding into the centre, jumping to the outer, and across the the rotor button.

Idea was that there would be a cpacitive build-up until the gap broke down, and then a bigger spark (or so I thought)...grabbed the silly thing to move it out of the way when I was setting the timing...have NEVER had a bigger belt out of an ignition system.
 
Originally Posted By: Shannow
Plug wasn't really a surface gap, looked more like it just had the electrodes chopped off, and was jumping from the tower to the side shell...not sure if it could increase the spark power as suggested, as with that arc length, it would be drawing pretty thin.

The picture of the three electrode plug gave me the giggles.


You are right about the chopped ground electrode. They said:
Quote:
modified spark plugs with no [...] ground electrodes


I'm surprised the engine ran with such castrated plug with a monstrous gap.
I may try it at home, but would that damage the coils (too high voltage)?

What picture of 3-electrode plug?
 
They say its a commercially available spark plug. Since such plugs are available (and apparently have been for a long time) I see no reason to disbelieve them.

If modified spark plug meant "home made" that'd imply they welded additional ground electrodes on to create the multi's. Seems unlikely.

Re "3-electrode", if you find typos funny, you should try proof-reading for non-native (Chinese) speakers of English. You'd bust a gut, but easy money it ain't.
 
Originally Posted By: Ducked
They say its a commercially available spark plug. Since such plugs are available (and apparently have been for a long time) I see no reason to disbelieve them.

If modified spark plug meant "home made" that'd imply they welded additional ground electrodes on to create the multi's. Seems unlikely.

Re "3-electrode", if you find typos funny, you should try proof-reading for non-native (Chinese) speakers of English. You'd bust a gut, but easy money it ain't.


Take a 4 electrode plug, remove 2, and it's a 2 electrode. Remove one of them, it's single electrode, and that one removed makes it no electrode.
 
I think they bought 1 Bosch +2, 1 Bosch +4, and 2 Bosch single platinums. Then they cut one ground in a single platinum hence the "modified plug." Very low budget study, but intriguing results nevertheless.

or maybe the "modified plug" was naturally occurring? It happens with Bosch plugs sometimes.

DuuuuuuuuudesBoschPlugGroundBreakoff.jpg
 
Could be. I still don't see any reason to disbelieve the "commercially available" statement, but then I've never seen a surface discharge spark plug.

Are y'all assuming its "field modified" because of its appearance?

For example, in the no-earth-electrode plug, would the centre electrode be more recessed if it was bought off the shelf?
 
Google is your friend...just google "surface gap plug", and you can see one...they have a...well, I would describe it as a "surface gap", not a leap of faith that the charge will surround the centre insulator and jump backwards to the side shell.

Besides, you can see where the side electrode was hacked off the plug with no side electrode.
 
Speaking of hacking off plugs, lots of people cut ground strap short, call it side gapped and swear by the benefits. I have never done it myself, but tempted.

29889d1282107715-spark-plug-mods-plug-side-gap.jpg
 
People swear by non-detergent oil too. At one time people swore by drinking mercury compounds.

So the plug designers are missing out on some sort of benefit that they don't know about?

Originally Posted By: friendly_jacek
Speaking of hacking off plugs, lots of people cut ground strap short, call it side gapped and swear by the benefits. I have never done it myself, but tempted.
 
Originally Posted By: kschachn

So the plug designers are missing out on some sort of benefit that they don't know about?


Some of the greatest discoveries of all time were done by non-experts thinking outside the box. Think Da Vinci, Einstein, etc. You don't deny this, do you?

But coming back to your question, IMHO, the side gapped idea is not commercially viable due to short service life of such a plug (rapidly increasing gap).
 
Lol, Einstein and da Vinci were not "non-experts".

And yes I will deny your premise in regards to spark plug technology.

Originally Posted By: friendly_jacek
Some of the greatest discoveries of all time were done by non-experts thinking outside the box. Think Da Vinci, Einstein, etc. You don't deny this, do you?

But coming back to your question, IMHO, the side gapped idea is not commercially viable due to short service life of such a plug (rapidly increasing gap).
 
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