Copper v. Platinum v. Iridium

XJs dont run high energy ignition systems, and the main reason for us to replace plugs is due to fouling NOT electrode wear. Having a spark plug that will last 100,000 klms of wear is not useful if it is getting contaminated.
We are creating a spark under pressure between 2 electrodes using a finite electrical potential. There are no huge advantages in that spark energy to be had by changing the type of metal on the electrodes.

 

Not enough to be measured with a timing light, until you get to the point of a continuous missfire.

I have done this to solve an argument. Try it.

 

I dunno. NONE of my used XJ plugs are fouled or contaminated; I replace them because the ground strap erodes to where it has a soft, rounded section compared to the nice sharp rectangular cross section of a new plug's ground strap. The tip of the electrode likewise becomes gently rounded; once deteriorated, I replace the plugs.

For me, that's every 2500~3000 miles or so in a properly tuned stock 550 that sees a lot of high-speed miles, running stock NGK D8EA plugs.

Cost is less than a tank of gas, so I simply consider it part of keeping the motor running at its best.

 

Currently running stock NGK's. I haven't tried them, but E3's have been independently tested to increase the flame front and dispersion of flame-which leads to more complete and more powerful combustion. How much? Well that's the question to have answered, and I wouldn't go by manufacturer's tests-only a real world test would convince me. But if they improved power/fuel economy even a little I would buy them.

 

Fitz, don't cut the wire, just pull the boot up off the plug a little.
last time i changed plugs, about two years ago, i bought eight and swapped them around to index them. got three right on and one close.
did it do any good? i doubt it but i've got indexed plugs and i sleep better at night

 

The invention of the first commercially viable high-voltage spark plug, as part of a magneto-based ignition system, by Robert Bosch's engineer Gottlob Honold in 1902 made possible the development of the internal combustion engine.
Subsequent manufacturing improvements can also be credited to Albert Champion and others.

It the device that makes Internal Combustion Plants ... possible.

From 1902 to 2012 the Automotive Industry's growth went Global.
Manufacturers who can attract even a small niche' ... a small fraction of a percent ... of the Global Automotive Parts Market ... make vast fortunes if they can get consumers to buy their parts.

The Basic Spark Plug has remained the same for all those years.
Protected by Patents.
Some Patents expired allowing for competitors to sell a different Brand.

To be able to enter the market and not violate Patent rights; "Different Designs" were introduced along with claims of superiority.

The MISSION of the Companies which have emerged with variations of Electrodes and Ground Straps with claims of providing a better Spark than the designs of Pioneers and their improved manufacturing processes is NOT about performance.

It's about SALES.

 

I read it somewhere a long time ago, so I went looking for it - Google Images, tune-up articles, old VW info, then I just took a hammer and smashed a Bosch Platinum plug open. No air gap.

Odd that the center electrode does NOT conduct electricity, according to my Digital Multi-Meter.

I'm not wrong, just mis-informed

 

here's a thread from kzrider on plugs, gaps, coils and all that stuff, good read.
http://kzrider.com/forum/4-electrical/3 ... o-you-run-

 

I replaced my plugs recently at 11,000 klms when I was about to do a dyno run (before removing the old engine). They were oil fouled due to the condition of the old engine. It will be interesting to see what mileage I will get out of the plugs with the new engine. Possibly shorter because of the engine mods, which I expect will require colder plugs.

 

Wait... whaaaaat? Something is amiss there. Either I'm misunderstanding what you are saying or had a piece of ceramic posing as a spark plug.

That lack of continuity would suggest there's an air gap, though.

Lastly, NEVER trust a multimeter to tell you if something conducts or not. They will only tell you if something is a dead short ... to DC. And those pulsed currents are anything but DC. So even if you measured the resistance with a DMM, you are only measuring the DC resistance. It's a whole different world when you have time-varying voltage and current.

 

My new NGK BP7ES and some old AC plugs conduct,
but SOME of my Bosch Platinums (used) don't conduct, even after sanding the terminals.

 

That's interesting. Again, though, you've got your DMM on diode-check. i would suggest setting it to ohms and checking the actual resistance. And even that won't give you a clear answer. But if your plugs normally conduct and a few don't... well then something is clearly different with those that don't. Perhaps it's inside the threaded bit?

 

I had this discussion with a friend who was on a professional motorcycle mechanic course at Merton College. They had had a visit from a NGK spark plug salesman (I think, at the time Champion were advertising 100% copper plugs) and were told that they had a solid copper core all the way through.

I told him this was nonsense. I had an idea that there electrode was in two parts and joined with a paste, which could be damaged by petrol penetration if the engine was run with that cylinder not firing. I never had any evidence apart from my own thought to back that up, but spark plugs run in non-firing cylinders do seem to die.

Whether I was right or not, I put an old plug in the vice and liberally applied tender care to separate it into its component parts and showed him where the two parts of the electrode were joined. It did look like there was a paste joining them, but it's just as possible other manufacturers could have a small air gap, or maybe just a conductive paste which is less than 100% effective, and still transmit a spark.

Compared to bikes I had in the past, I think of XJs as high energy systems. I had Czech two-strokes, Jap bikes with magnetos and still have a Sanglas 500. The 10-20,000 volts of 80s Jap bikes should be enough for what we need. I don't doubt that you can get higher powered systems now, but then you have to get into all the theories about HT leads as well to get full benefit from it I suppose.

 

Power isn't just in the voltage, it's the current behind that. P=I*V, and so many things in that spark plug, the wires, the mixture, the ignition coil (or the digital ignition system) will all affect that.

The "paste" may be a dielectric gel. This would make whatever gap the paste was filling become a capacitor (which is exactly what a spark gap really is). And this would allow the charge to reach a certain point, then arc through. It would seem odd to do it that way, though, because any dielectric I've ever heard of would create a carbon trail after one firing and then begin to conduct instead of hold off charge.

If I have time after fighting with a broken intake bolt and a broken filter housing bolt I might just feel inclined to dissect an old plug. I mean, at least that's one thing I could break that would be somewhat productive!!!!!!

 

If I had a dollar for every low-time conventional NGK (not the Platinum and/or Iridium NGKs) that would fire outside the cylinder, but NOT inside under compression, I'd have a lot of dollars. Cleaning makes no difference, and they almost never show ANY noticeable electrode erosion. We have seen this for years now, but don't see it with the other brands of conventional plugs we use (typically equivalent Autolites these days). We've even had customers come in without the bike/atv, etc. involved and ask us about this same NGK problem that has occurred REPEATEDLY to THEM. We tell them what to use, and they tell us later "Problem solved, thank you".

 

Yep - they wear out, but what causes it and what is it that failed ?

A flooded, non firing cylinder at 200psi - could it force petrol up the side of the electrode ? What would the effect be ?

Are NGKs the only plugs to have a two part electrode (presumably not) and are they still made the same way ?

Why does a brown cow give white milk when it only eats green grass ?

 

what would the # of a plug with a air gap be? mfg's break the plug # down to what each part means, anyone ever see "air gap = .15".
how about "new improved air gap", "super air gap", "surefire air gap"
"air gap between my ears". why would it be a secret? we got a air gap and they don't, don't tell anybody.
they used to call bosch plugs with a center electrode and four side electrodes that you didn't set the gap on "air gap plugs" maybe that's how this got started.
or maybe their marine plugs that float if you drop them in the lake?

 

greg_in_london: Very good questions that I don't know the answer to (yet). Being an old Mechanical/Aerospace Engineer I would love to find the time to find out what's going on. I DO know that NGKs of 20-30 years ago didn't do this crap. They were FINE spark plugs.

P.S. I'm not even referring to fuel-SOAKED plugs here, in fact most of them wouldn't even be accurately described as fouled. But, even if a new plug IS fuel-soaked, there's no excuse for this kind of permanent loss of function.

 

Look at Extra Large Plug "Cut-away / Schematic"

Scroll down at this site:

http://forums.vwvortex.com/showthread.p ... r-problems

 

I see the suspicious-looking (soft?) stuff in the cross-section, but what is it??