Iridium plugs: cleaner emissions, better mileage?

[Bottom_Feeder]

I know iridium spark plugs are supposed to have benefits mainly geared towards plug service life, but they also talk of better ignitability, cleaner emissions and better fuel economy. But has anyone run iridium plugs in a car not originally specd for them, specifically with an NA engine, and found any of that to be true?

 

[Rand]

it would depend on the application

 

[JOD]

I think it's kinda going down the rabbit hole to try and quantify fuel economy gains that small. I mean, fuel economy isn't even static, since as tires wear they have lower rolling resistance. My lifetime best mileage has been after I changed to Iridium plugs, but there's far too much other stuff going on for me to make any wild claims.

Do any of the mfg's of Iridium plugs make any specific claims with respect to FE?

 

[ECUpirate]

I ran the Bosch Iridium plugs for 45k miles in my 99 Expedition 5.4. Can't tell a difference between those and the NGK G-power plugs I've been running for the last 25k, except the Iridium plugs were over 2x the price.

 

[GC4lunch]

Originally Posted By: Bottom_Feeder
I know iridium spark plugs are supposed to have benefits mainly geared towards plug service life, but they also talk of better ignitability, cleaner emissions and better fuel economy. But has anyone run iridium plugs in a car not originally specd for them, specifically with an NA engine, and found any of that to be true?

The reason to use iridium plugs is to get better service life. NGK, who would have the most to benefit from being able to cite perormance gains, debunks the hype here: NGK FAQs

Originally Posted By: NGK
Many people think that simply supplying more spark to the firing tip can and will combust more fuel. What they don't understand is that most newer cars' engines are so efficient that they are already burning all of the available fuel. Simply adding more spark voltage can't burn more fuel because there is no more fuel to burn.

 

[randomhero439]

A copper plug will fire the same as a iridium plug. Iridium plugs just fire more consistantly 3-4x long.

 

[GMBoy]

Originally Posted By: randomhero439
A copper plug will fire the same as a iridium plug. Iridium plugs just fire more consistantly 3-4x long.


BINGO! Very well said. It does not matter what material the plug is be it copper, platinum or Iridium. You will not gain power, MPG's or better emmisions from a certain type of plug. HOWEVER, over time and miles a long life plug (plat/irid) will continue to run cleaner and better than a standard copper plug. Basically, a copper plug at 30k miles is near it's useful life and probably missing a little contributing to higher (slightly) emmissions and fuel use. The long life plugs will not start to degrade until quite some time later usually around 75-100k miles. Some more some less. I've had OEM platinums fail at 50k miles and others were fine when changed at 90k.

 

[Trav]

The finer firing tips of Iridiums and platinums are much easier on ignition coils than the old copper plugs.
Easier starting.. Yes. Especially in cold weather when cranking speed and voltages may be lower.

Better fuel economy.. If the ignition system is in good shape probably not initially.
As the coppers age slightly their gaps erode quickly the misfire count may increase so in that case its possible in the long term.

Cleaner.. Ditto

More HP.. Ditto

Longer lasting.. Definitely.

 

[Voltmaster]

The "perfect spark" can bring up fuel economy and cleaner emission because the computer is perfectly tuned and its just matter of the spark igniting...


If spark is done at perfect timing there is less fuel waste which brings up both fuel economy and better emission...

Irridium is 2nd most dense matrial , and it can withstand spark which is why they are GREAT for spark plug application.

Just buy them, they are better quality. only a couple bucks difference vs platinum.

 

[NHGUY]

I run NGK Iridiums in the 88 Aries,originally the car came with Champion RN12YC.I notice immediate warm weather re-starts,and a little better throttle response but no better mileage.It runs very clean though.Absolutely no deposits on the 02 sensor whatsoever.Normally,you see black soot no matter the vehicle.

 

[dparm]

The only one that will give better ignitability is the Denso Iridium with the 0.4mm tip (sharpest you can get). Otherwise, no different than a platinum in that regard.

 

[Trav]

Both platinum and iridium ignite easier than copper. 0.4 tips are short lived.

 

[LeakySeals]

Iridium plugs require 5,000 less volts to make a spark than conventional plugs. Would think that's less taxing, extending the life of ignition and electrical system components?

 

[hounddog]

First off the COPPER is in the CORE. NOT the TIP. The TIP is what fires and wears. Most ALL plugs are copper core. I installed Autolite Xp Fine Wire Irdiumns with COPPER CORE in my 2009 Dodge Hemi. Thought it was imagination . Better idle. Fuel mpg hit the highest I ever got right after install. Then I found others posting same results. So NOT my imagination! I did some SEARCHING and READING about FINE WIRE IRIDIUM. This type plug is thought highly of in the aviation industary. They go on about long life,better burn,less carbon buildup,less voltage to ignite and such. I have run them 10,000 miles. They are warrantied 5 years UNLIMITED miles! Just remember the COPPER is in the CORE and used by most all plug manufactures. It conducts electricity better then other metals. BUT the TIP is what wears be it nickel or Platinum or Iridium. Nickel being the cheapest fastest wearing of them.

 

[Clevy]

Originally Posted By: hounddog
First off the COPPER is in the CORE. NOT the TIP. The TIP is what fires and wears. Most ALL plugs are copper core. I installed Autolite Xp Fine Wire Irdiumns with COPPER CORE in my 2009 Dodge Hemi. Thought it was imagination . Better idle. Fuel mpg hit the highest I ever got right after install. Then I found others posting same results. So NOT my imagination! I did some SEARCHING and READING about FINE WIRE IRIDIUM. This type plug is thought highly of in the aviation industary. They go on about long life,better burn,less carbon buildup,less voltage to ignite and such. I have run them 10,000 miles. They are warrantied 5 years UNLIMITED miles! Just remember the COPPER is in the CORE and used by most all plug manufactures. It conducts
electricity better then other metals. BUT the TIP is what wears be it nickel or Platinum or Iridium. Nickel being the cheapest fastest wearing of them.


I changed the plugs in my hemi a few weeks ago. It looked as though the old ones were still the original equipment. The ground strap was eroded in the middle.
Anyways mileage didn't change much if at all. I used ngk platinums. I did notice,like you,easier starting. It felt like it caught quicker. I used platinums simply because of how much of a pain it is to do them on this truck.
I usually use copper because it gives me a chance to read them,see if there is any oil on the tips etc. they are real easy to do on the mustang.

 

[GMBoy]

Originally Posted By: Trav
Both platinum and iridium ignite easier than copper. 0.4 tips are short lived.



I agree. Smallest with long life is 0.6. Those last. NGK has 0.4 plug that is NOT a long life plug (listed their website as a 30-60k mile plug) and was designed for performance first, life 2nd.

I get great results out of the Autolite Iridium Xp's with the 0.6 fine wire tip. Price is fair, too.

 

[mechtech2]

Originally Posted By: GMBoy
Originally Posted By: randomhero439
A copper plug will fire the same as a iridium plug. Iridium plugs just fire more consistantly 3-4x long.


BINGO! Very well said. It does not matter what material the plug is be it copper, platinum or Iridium. You will not gain power, MPG's or better emmisions from a certain type of plug. HOWEVER, over time and miles a long life plug (plat/irid) will continue to run cleaner and better than a standard copper plug. Basically, a copper plug at 30k miles is near it's useful life and probably missing a little contributing to higher (slightly) emmissions and fuel use. The long life plugs will not start to degrade until quite some time later usually around 75-100k miles. Some more some less. I've had OEM platinums fail at 50k miles and others were fine when changed at 90k.


With the copper being in the core, why not use copper iridiums?
Iridium has less resistance than platinum, but compared to the extreme resistance of the fuel air mix that the spark has to 'jump' when firing, it is practically negligible.

 

[dparm]

Correct, the 0.4mm is supposed to be replaced every 20-30k. It's a performance plug, but I'm fine with that. It's why I buy them.

 

[SteveSRT8]

Originally Posted By: GMBoy
Originally Posted By: Trav
Both platinum and iridium ignite easier than copper. 0.4 tips are short lived.



I agree. Smallest with long life is 0.6. Those last. NGK has 0.4 plug that is NOT a long life plug (listed their website as a 30-60k mile plug) and was designed for performance first, life 2nd.

I get great results out of the Autolite Iridium Xp's with the 0.6 fine wire tip. Price is fair, too.


Likewise. Most modern cars can practically spark off a pine log, so plugs don't make much difference in real world performance or economy.

However, many higher output motors can feel a "sharpness" or "responsive" reaction to a fine wire design, especially if their ignition system is not as strong.

My small block based 420+ c.i. stroker with an old MSD setup really likes the fine wired plugs. But in my car with 16 plugs there is no discernible difference with almost any plug!

 

[GMBoy]

Originally Posted By: mechtech2
Originally Posted By: GMBoy
Originally Posted By: randomhero439
A copper plug will fire the same as a iridium plug. Iridium plugs just fire more consistantly 3-4x long.


BINGO! Very well said. It does not matter what material the plug is be it copper, platinum or Iridium. You will not gain power, MPG's or better emmisions from a certain type of plug. HOWEVER, over time and miles a long life plug (plat/irid) will continue to run cleaner and better than a standard copper plug. Basically, a copper plug at 30k miles is near it's useful life and probably missing a little contributing to higher (slightly) emmissions and fuel use. The long life plugs will not start to degrade until quite some time later usually around 75-100k miles. Some more some less. I've had OEM platinums fail at 50k miles and others were fine when changed at 90k.


With the copper being in the core, why not use copper iridiums?
Iridium has less resistance than platinum, but compared to the extreme resistance of the fuel air mix that the spark has to 'jump' when firing, it is practically negligible.


I agree with you. My comment never said anything about not using them. I was simply discussing regular all copper (old style) plugs vs the precious metal tipped ones.