iridium plugs. do they make a difference

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performance wise? besides the long life, are there any other benefits of running an iridium plug? could i pick up performance by using a platinum or copper plug in my vehicles?
 
Originally Posted by Jimzz
No real world difference. The material is about lifespan.


Yes, it's about lifespan.

If you want performance, use copper and then pull them to do maintenance every few thousand miles. Which is why we like iridium.
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Originally Posted by WhyMe
performance wise? besides the long life, are there any other benefits of running an iridium plug? could i pick up performance by using a platinum or copper plug in my vehicles?


Copper has the best performance of all three (Iridium, Platinum, Copper) and the worst longevity

Here is an in depth thread on the subject.

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2583605
 
They make your wallet lighter.

IF your car says to use a certain plug (copper?) use that.
 
What about the ruthenium plugs!
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They "claim" performance improvements:

- Ruthenium HX provides more complete fuel burn than other precious metal spark plugs, resulting in quicker throttle response, smoother idle and better cold starts.
- Ruthenium performs better at high temperatures in various driving conditions compared to the leading precious metal spark plugs.


0.7 seconds time improvement!
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Originally Posted by talest
They make your wallet lighter.
If you have to change a $5 plug every 25k miles vs a $10 plug (Iridium) every 100k miles, uhhhh, no. At least not in the long term. I just used typical values in my example of course, but the Iridium values are pretty accurate.

Originally Posted by talest
IF your car says to use a certain plug (copper?) use that.

Almost always safest / smartest to use whatever plug type the vehicle manufacturer says to use.
 
Not for a daily driver, but if you were racing at extended high RPMs or your vehicle has weak failure prone ignition coils, then the lower resistance of iridium plugs or especially copper (over plat.) along with non-resistor wires could help, and also potentially wreck your radio reception. Copper or iridium plugs alone, used with stock resistive wires, make minimal difference (from the minimal resistance difference). Modern engines may benefit more from the more durable iridium which allows making the electrode smaller for a very slight increase in combustion speed. Again this is mostly for high RPMs not a daily driver, and if you leverage the durability to make the electrode smaller, you also erase some of the durability benefits.

For a daily driver with very hard to access plugs (whole intake has to come off for example), I'd use iridium for that reason if it's the first plug swap. If it's the 2nd or especially 3rd plug swap, make your best guess whether there are enough miles left in the engine that you'd need to change the plugs again if they were platinum. Then again the older an engine gets, the more I prefer pulling the plugs on a shorter interval so they don't get seized in and so I can examine them to get a better idea of how the cylinders are doing.
 
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I don't think you really understand how a plug is constructed. The precious metal plugs (i.e., platinum, iridium, ruthenium) only have precious metals used sparingly at the tips. All(?) plugs have a generous section of copper in the core conductor. The tiny amount of precious metal used at the tip should not affect resistance any.

The electrical resistance for radio interference suppression comes from a mixture of graphite and glass in the electrode conduction path behind the copper core.
 
Originally Posted by doitmyself
What about the ruthenium plugs!
21.gif


They "claim" performance improvements:

- Ruthenium HX provides more complete fuel burn than other precious metal spark plugs, resulting in quicker throttle response, smoother idle and better cold starts.
- Ruthenium performs better at high temperatures in various driving conditions compared to the leading precious metal spark plugs.


0.7 seconds time improvement!
[Linked Image]

[Linked Image]



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Originally Posted by DrDanger
From a low mileage guy, like me, I felt a nicer throttle response going from NGK copper to Denso Iridium.

Probably because the old ones were worn, which they do faster than the iridium ones.
 
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Less than 10k km on them so I doubt it. A finer tip ,on the other hand , which is better at concentrating electrical charge is a more plausible argument.
 
Back in '77, I had a Honda Civic. It had a tiny battery, and the conductor in the battery cables was about the thickness of a #2 Pencil *lead*.

(I found that out the hard way, -20f, no startee).

That's when I started clipping the side electrode shorter and pointier. (I also did the same on my RD350, which had a terrible weak spark).

That helped significantly with starting (the RD ran to redline in 5th gear. It wouldn't before that).

I think these new fine-wire designs are great, and will make some difference. Although the modern ignition systems are just so good...
 
Originally Posted by DrDanger
Less than 10k km on them so I doubt it. A finer tip ,on the other hand , which is better at concentrating electrical charge is a more plausible argument.

Okay sure.
 
Ruthenium plugs seem to be the most economical choice. According to the press releases they last 20-40% longer than iridium.
 
When I used NGK Iridium IXs on a old Nissan, no difference. I went with NGK G-Power on that old van as a slightly longer life plug than the stock V-Powers. I think if you want to upgrade to precious metal on a car with regular plugs, go with double Pt/Ir plugs so you get the longer life. The Denso TT designs are also good.

All spark plugs have a copper core. The tip is what makes it different. What we call a copper plug is actually a Ni/Cu alloy at the firing tip.
 
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