why the expensive plugs

[Car Luver]

Seems like all the new cars are getting the fancy iridium plugs. Why? For longevity?only cahnge them every 100k?lets say my car came oem with them fancy plugs. could i change them out later with regular plugs?I rarely run my plugs more then 30k before I replace them anyways.

so what are the advantages to them new fangled plugs?

 

[T-Keith]

A smaller tip means a better spark too. Good Iridium and platnium plugs do live up to 100,000 miles. That said I've seen certain brands go out much sooner. I'd go with NGK or AC-delco, stay as far away from Bosch as possible. They have a pure platnium electrode that wears out quickly with modern ignition systems.

 

[Tosh]

I believe the main advantage of fancy-tipped spark plugs is to meet emission control requirements out past 100k.

 

[Gary Allan]

I'll go with Tosh's explanation. Many consumers may opt out of this service if the car is running okay if confronted with the dealership service rates. This moves one more item beyond the manufacturer's responsibility for emissions compliance. This item can effect the longevity of other components that they're responsible for (cat, EGR, etc.)

 

[Kestas]

quote:

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Originally posted by T-Keith:
A smaller tip means a better spark too...

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More than once on this board I've asked about tip size/shape and its affect on spark performance. My thought is that perhaps the electric potential field is more concentrated if you had two sharp opposing tips, as opposed to a splitfire or four-tipped design, and that two sharp opposing tips would give a healthier or more reliable spark.

The answer from forum members is that it doesn't matter. So I guess this subject is still open to discussion.

 

[m2200b]

Longlife plugs also make the change for hard to reach ones further apart.

 

[mechtech2]

Mfrs. have to comply with Federal laws about emmissions. Cars have to be able to pass for a certain amount of miles.
Platimum plugs [or iridium] allow this.
Platinum is long lasting, but not a very good conductor. That is why the tips are small [also because it is expensive].
Iridium is an excellent conductor, and very long lasting. If you have stock iridium plugs, be happy. You may want to take them out now and then just to ensure that they don't seize in the head.
Multi tipped plugs inhibit flow in and out of the firing area. Only one tip fires at a time.

 

[Kestas]

It's mainly because the average customer doesn't want the expense of taking the car to the mechanic every 30K. That's why you're seeing certain technologies coming onstream, i.e., electronic ignition, lifetime transmission fluid, lifetime Ford air filter, in-tank fuel filters, permanently sealed wheel bearings.

The technical advantages of the tipped plugs are that there is considerably less electrode erosion, plus they handle a wider heat range.

If you read some of the posts here, you'll find lots of people who have problems with these plugs well before 100K. This mileage is more of a goal than something actually achieved. 50K intervals are more realistic.

You may be able to use regular plugs with 30K intervals, but the plugs would need to have the same resistance characteristics. Plugs are something I personally don't mess with. I don't try to reengineer plug use because I don't know what I'm doing. The rule of thumb is that OEM design plugs are best for your engine.

 

[OBIO3]

My 2 cents worth. I refuse to run platnium plugs simply because they do not function as needed in a gas engine. Platnium plugs have very low resistance (7,000 OHMs) allowing arc over early causing the ignition(coil) not to deliver a hot spark. In otherwords, You get a week spark with platnium plugs. This can be a good thing IF your ignition system(most likely your coil) is weak but a lot more desirable to fix the ignition which includes plug wires IF YOU HAVE THEM. Now.... Lets go the other direction. CHAMPION PLUGS have the highest resistace of all the plugs far a I know. They give 75'000 OHMs resistance so arc over is held back till a really good spark builds up. Good as it gets....Almost lol.... CHAMPION TRUCK PLUGS are better yet at 85,000 OHMs resistance and the only Plug I run.; There tops in my book because they give you everything your engine wants. If your ignition system is in good condition and you try these truck plus, you will be impressed.

 

[Quickbeam]

Yikes.

 

[punisher]

My 2 cents worth, I don't let Champions go into any of my engines.

The resistance of a plug has very, very little impact on the voltage of the "arc". The factors that determine arc voltage are gap, electrode diameter and cylinder pressure. As each of the afore mentioned increase, the voltage required to jump the gap increases as well.

Platinum and iridium plugs are used to meet required warranty commitments as well as make customers happy by having a "100K mile plug". Iridium and platinum are used mainly because they do not erode at anywhere near the rate of copper. Another plus is that the electrode tips can be made smaller, thus reducing voltage requirements from the ignition system. It is true Champion truck plugs require a higher voltage to fire, because the electrode is a comparitively larger diameter at it's tip as compared to other plugs.

Best advice- run what your owners/maintenance manual says to. There are no wonder plugs no matter what JC Whitney says.

 

[Kestas]

quote:

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Originally posted by punisher:
... because they do not erode at anywhere near the rate of copper...

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I don't believe the tips are copper. Copper is in the plug core for thermal and electrical conductivity. I believe the tips on regular plugs are nickel.

 

[mechtech2]

Champions do NOT have 75,000 Ohms resistance.
That's silly.
The type of tip has no influence on the resistance.
That is in the internal part of the spark plug.
4-7,000 is good to have, for radio and firing reasons.
Compare this to the extremely high resistance of the gap that the plug has to fire in, with high pressure making it worse. It is insignificant.

 

[PandaBear]

Why Should I Use Platinum Spark Plugs in My Teg?

 

[Quickbeam]

Yes, right on. Regrettably, OBIO3's post flys in the face of basic ignition and electrical theory in several ways. The voltage required to fire a plug is a function of gap, cylinder pressure, and mixture. Plug "resistance" has no bearing. Anyone trained in secondary waveform analysis can attest to that. Analyzing the firing and spark line is the best way to see what's happening in individual cylinders.

Iridum/platinum eletrodes are used for the reasons stated: reduced erosion and longer life. They were initially introduced for waste spark DLI systems to reduce erosion caused by companion plugs firing opposite polarity. This causes increased erosion the same way GTA electrode positive welding does. The plasma physics are the same in each case.

 

[JetSnake]

You use words like "new fangled" and "fancy" when talking about newer OEM spark plugs. I have to ask one question. Do you know how to change the time on your VCR?

 

[Louie's gone fishing]

If you choose to not use iridium plugs in a car that came with them, be sure to recalibrate your car's brain. The ignition system uses feedback in the secondary part of the system as part of it's ongoing calculations for spark timing, intensity, duration and latency. Those engineers don't know everything. You parts counterman may have it on good authority that a standard plug is just as good, and a lot cheaper, too. Let him pick the heat range to make sure you get it right. Once you've got the spark plug stuff handled you might want to take on fuel controls, next, or maybe those pesty O2 sensors. With a wire brush and some sand paper, who needs a new one, anyhow?

 

[Car Luver]

well i know how to use them new fangled computers

 

[JetSnake]

quote:

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Originally posted by Car Luver:
well i know how to use them new fangled computers

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That's good. Didn't mean to give you such a hard time. All in fun. Well, for me at least.

 

[TheTanSedan]

I chose DENSO Iridiums (stock heat range) for my truck 1-1/2 years ago. I'm 20,000 miles into them and pleased. Changing them is, regretably, harder to do now that health is a goner.

I'll pull a few at some point before 100,000 miles on them to "read" them (that would be at 195,000 miles).

Or not.