opinion on iridium plugs

[wayne cooper]

Hitachi anyone?

Have been running the Hitachi GT (L 23W) and have had no bad luck with them so far. I don't think that they are better than NGK, just different. Kinda throws a curve into the spark plug conversation for a bit. Although I do like to BS the "plastic" kids at the coffee shop into thinking that they are the hot setup. Would be kinda funny if all of a sudden a dozen or so riders start to ask for them at their local bike shop.

[cberkeley]

Ok so the bike's working great and the plugs all sport a nice tropical tan and such. The Koso Temp gauge went haywire but I fixed the pinched sensor wire. So with nothing else to do I've been switching back and forth between the stock NGK D8EA plugs and NGK Iridium DR8EIX I can percieve no difference between them. Of course this is all very subjective (they both have that nice tan) as I have no way of measuring it. I'm running on the Iridiums for the braggin' rights.

[Mike McNaney]

Guys, here's the scientific truth. A spark plug is a spark plug is a spark plug.

Electricity will travel the path of least resistance ONLY. No matter what else you do. One spark per pulse. You can change the characteristics of the spark such as multiple pulses, higher intesity etc but it will only jump from sharpest point to sharpest point. The characteristics are determined by the ignition system. sometimes an ignition company will suggest a certain plug due to its resistance value working well with their system. Or the intensity of the spark needs a harder metal for adequate life, etc.

The differeces are in the hardness of metal which will make it last longer. Standard AC plugs are notoriously made of softer metal and last the least amount of time. Platinum would of course last longer.
OR to make it last longer you can add more grounding straps. one, Two and four are the popular amounts. After one strap wears back a bit then the spark jumps to the next sharpest. Alpha Romeo's old 4cyl motors use a stock four ground plug.

There are ways to manipulate the spark to your advantage but you can do it to ANY spark plug with equal results.

These are called side gapping and indexing. These are racing tricks and are used to point the spark in a certain direction within the chamber for various reasons depending on swirl, chamber size and shape, etc.

Spark plug "technology" is primarily used to increase the profit margin of the making company.

Of course Quality of materials and workmanship is a variable to consider and these will effect performance negatively but nothing can effect the performance of a spark plug positively from an energy standpoint.

[themess]

The differeces are in the hardness of metal which will make it last longer. Standard AC plugs are notoriously made of softer metal and last the least amount of time. Platinum would of course last longer.

It's the resistance to corrosion of the metals, not their hardness. Iridium is one of the "platinum metals", which also include ruthenium, osmium. rhodium, and palladium. This group is in turn a subset of the "noble metals", which also includes silver, gold and mercury. The term noble metal is related to the term "noble gas", which once meant "inert gas", or one that engages in no chemical reactions. It turns out that everything is chemically reactive under the right conditions. The same applies to the metals - while they aren't inert, they react with very few things, and only under extreme conditions. Spark plug electrodes are exposed to very high temperatures and corrosive gases. The spark itself is probably by far the highest temperature in the combustion chamber. As the fuel ignites, it doesn't go directly from gasoline and oxygen directly to water and carbon dioxide, there are lots of intermediates along the way, and some of those are very corrosive. A thin coat of any of the noble metals on the electrode should greatly extend the life.

[Mike McNaney]

Not a metalurgy class but However you'd like to term it, its the same, resistance to corrosion, density and hardness follow each other except for as you pointed out, Gold etc which cant stand the pressures being so soft.

SOooo...resistance to breakdown is the only difference in sparkplugs. Thanks for the help.

Im holding out for the depleted uranium plugs to come out. Ha!

[tkent02]

My question is who cares???

ON a vehicle with impossible to reach plugs you need the ones that last the longest, but on a GS it takes about two minutes to change them all, so who cares how long they last?
My truck took several hours and I never got the last two, need to raise the motor up to get them. I still have scars on my arms from the attempt.
But a GS?

[Mike McNaney]

Yes, There you go.

[Mysuzyq]

[QUOTE=Mike McNaney;603092]
There are ways to manipulate the spark to your advantage but you can do it to ANY spark plug with equal results.
These are called side gapping and indexing. These are racing tricks and are used to point the spark in a certain direction within the chamber for various reasons depending on swirl, chamber size and shape, etc.QUOTE]

Interesting...my (maybe stupid) question re. indexing the plugs.... as I understand it, washers are used to seat the plug , so the plugs end up oriented in the desired direction....but... won't shimming the plug like this raise it a little as well, relative to the combustion chamber and somewhat negate the effect?
Also, one of the claims made by the Iridium plug co's is that they can fire at a lower voltage compared to conventional plugs, by virtue of the super-thin electrode...in effect (if true), fewer misfires, easier starting.....(don't people upgrade to Dyna coils etc for the same reasons?) although so far, I have'nt seen any proof of these claims....most users seem to agree that the resistance to fouling on these plugs is very good, and they out-last conventional plugs pretty easily, to justify the extra cost.

Tony.

[jknappsax]

Ford Aerostar

In the Ford Aerostar, the factory manual called for pulling the engine to change the plugs. It WAS possible to change them using extensions, u-joint adapters, but it took perseverence.

[Mike McNaney]

mysuzyq,
Thats Correct. So you must compensate for this by changing the heat range of the plug if needed. (length of insulator/electrode)
These are high performance tricks and for the person with their head in it. Engines with indexed and side gapped plugs arent running the factory recommended plugs or igition or compression or.......
Indexing plugs is usually done before the heads are put on the motor because each plug and head can have the threads started at a different point.
At the least, you mark the open face area with a marker on the sides of the plug and keep fiddling till the mark points in the desired direction when tight.

serious racing efforts include boxes full of spark plugs indexed to a specific head and cylinder to have enough for the season or until next teardown. the plugs will be marked for which head and which cylinder they go to.

The iridium plug being able to fire at lower voltages is a weird reason. Im not clear on why you would use a weak spark in the first place. Id spend the extra on new coils. All hi perf efforts Im privvy to try to increase the intensity and duration of the spark to get more complete combustion.
Using fancy metals for spark plugs is a marketing tool not a high performance tool.

[Thomas Kenny]

I put a set in my Honda VF750 Magna (1995) and I notice that startup is now immediate. Don't know if they do anything for my mileage however.

[cberkeley]

Naw, they'll just last forever:-D

[Mike McNaney]

I'll bet your old plugs were marginal in some way.

Every time you see an improvement, think first if it runs as good as new.

Our bikes should start immediatly. Mine does and its ignition is all new with the standard spark plugs

OR ..does it run better than new. If we buy a used bike or car and dont know what the benchmark is then we cant really say that the new parts improved performance. Maybe they just brought it back to where its supposed to be.

Performance degridation in spark plugs is slow and we dont percieve the difference until tune up time.

This reality is another tool used for marketing products to the masses.

Try a different set of new standard plugs to compare.
Truth in advertising is an extremely grey area having to do more with customer perception than reality.

[Mysuzyq]

The iridium plug being able to fire at lower voltages is a weird reason. Im not clear on why you would use a weak spark in the first place. Id spend the extra on new coils. All hi perf efforts Im privvy to try to increase the intensity and duration of the spark to get more complete combustion.
Using fancy metals for spark plugs is a marketing tool not a high performance tool.

I meant, they claim to require less voltage to produce a spark, and any hp improvements are due to eliminated or reduced misfires....their claims, not mine .. From the Denso site...

Q. What makes Iridium better?
A. Until recently, platinum was considered the best material to use on the top of an electrode because of its durability. However, Iridium is 6 times harder, 8 times stronger, and has a melting point 1200 degrees higher than platinum. Put that into a harsh environment such as an engine piston chamber, and you have a spark plug that can resist wear much better than platinum. Additionally, the DENSO Iridium Power alloy is so durable; it allowed our engineers to produce the world’s smallest center electrode (.4mm) which reduces the voltage requirements, concentrating its sparking power. Also, its smaller size, combined with the tapered U-Groove ground electrode, allows more room for the flame kernel to develop and produce a more efficient combustion.

The whole page can be viewed here....

http://www.densoiridium.com/faq.php

Again, these are the claims made by Denso....YMMV .

Thanks for the indexing explaination...next lesson = 'side gapping'

Tony.

[Mysuzyq]

[QUOTE=Mike McNaney;603261

Im holding out for the depleted uranium plugs to come out. Ha![/QUOTE]

These should be close enough..plugs with Polonium-210 radio-active electrodes:shock: .Ideal for soup-dropping .

http://www.theodoregray.com/PeriodicTable/Samples/084.1/index.s12.html

Tony.