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Author Topic: What is the advantage of silver spark plugs?  (Read 7570 times)

James Lewis Hartland

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What is the advantage of silver spark plugs?
« on: 12/02/2009 13:30:01 »
James Lewis Hartland asked the Naked Scientists:
   I am a retired Mechanical Engineer that's always had an interest in all
things, especially engineering. As someone who has always done his own repairs and servicing, I have used Platinum Spark Plugs in my cars for many years. However, spark plugs using other materials for the firing electrodes are now being promoted ie Iridium/Silver electrodes etc which seem to cost considerably more money.

Are there any performance advantages in purchasing these alternative
products and if so what are the advantages they provide?

Thank you,
James Hartland.
What do you think?


 

lyner

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What is the advantage of silver spark plugs?
« Reply #1 on: 12/02/2009 23:25:20 »
Silver is an excellent thermal conductor. A silver pin with a non reactive plating could be just what you need.
 

Offline LeeE

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What is the advantage of silver spark plugs?
« Reply #2 on: 13/02/2009 00:06:51 »
I believe that the greatest advantage from exotic spark plugs is increased profits for the manufacturer.  If you were to really believe manufacturer's claims for their newest products (and I don't just mean spark plugs) you'd end up thinking that the old products never could have worked in the first place.
 

Offline graham.d

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What is the advantage of silver spark plugs?
« Reply #3 on: 13/02/2009 12:24:18 »
I tend to agree with Lee. There are theoretical advantages but whether these are significant in any practical sense is open to debate. There are papers on the web which examine relative performance, but none I could find that were free.

A good website is:

http://www.periodictable.com/Elements/SparkPlugsGroup/index.html

 

Offline lightarrow

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What is the advantage of silver spark plugs?
« Reply #4 on: 13/02/2009 12:55:11 »
I'd like to know if Iridium/Silver is an alloy or the two metals are somewhat separated. If it's an alloy, it would also be interesting to see its melting point (Iridium melts at ~ 2450C while Platinum at ~ 1770C and Silver at 960C so if Ir/Ag is an alloy with low percent Ag, it could have an higher melting point with respect to Pt).
 

Offline CycleGuy

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Re: What is the advantage of silver spark plugs?
« Reply #5 on: 04/08/2015 07:41:58 »
LeeE is right. Variations on an aged theme utilizing different metals that have no discernible difference in the operation of the engine.

A few observations from what I've learned:
1) Those needle-fine Iridium plugs don't work so well with waste-spark systems. A waste-spark system generally fires two cylinders from one coil, and fires once to initiate the power stroke, and once during the exhaust stroke (the waste spark in the exhausting cylinder). It does this by routing the positive side of the coil through one plug, and the negative through the other, each time it sparks, it actually is firing two plugs in series.

The problem is that those needle-fine Iridium plugs have different characteristics than other plugs... one is that they require a lower forward voltage to fire because sharp objects have a higher surface charge and thus they ionize the surrounding atmosphere more readily, creating a channel to conduct the spark to ground. Conversely, the reverse voltage (on the waste spark) requires higher voltage because you're going from the flat J-strap electrode to the pointy center electrode. That gives you two distinct disadvantages... the lower forward voltage means a weaker but longer duration spark than you'd get from a non-Iridium plug, and the higher reverse voltage means it works your coil harder. My bike definitely did not like its Iridium plug. Ran rougher, didn't have as much power, and fuel economy dropped a good bit.

2) I've tried pretty much every type of plug out there in trying to get rid of a cold rough idle on my bike. In diagnosing the problem, I knew it was due to not lighting enough of the fuel when the engine was cold to get a stable idle (it's an ECU-controlled fuel-injected bike that doesn't like the ethanol in our gas, so there's not much I can do to change things). The only plug that completely cured the rough idle was the Pulstar HE1HT9 plug. The first start-up after I put it in, the engine idled at about 2450 RPM (it normally idles at 1700 RPM, the idle speed is controlled by the ECU) for the first 5 minutes until the ECU dialed back the idle air bypass valve to slow the idle down... so the plug made combustion more efficient, for sure. It wasn't "cold idle" that made it run fast, that only goes to 2000 RPM on this bike and only lasts about 10 seconds.
 

Offline syhprum

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Re: What is the advantage of silver spark plugs?
« Reply #6 on: 02/09/2015 23:32:44 »
I don't know about silver or platinum in spark plugs but platinum is very useful for contract breaker points if you have a pre transistor ignition system.
 

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Re: What is the advantage of silver spark plugs?
« Reply #6 on: 02/09/2015 23:32:44 »

 

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