What's the "BEST" spark plug?? (*not* platinum)

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Been doing some research. Started out looking up info on the E3 spark plugs because I've actually had good results with them in 1-cylinder motors (bicycle motors, lawnmowers, & such)... but I soon discovered that the makers of the E3 plugs are actually pretty small and are more than likely NOT able to offer you the proper plug for your vehicle. For example... was looking at spark plugs for two of my cars, and Denso offers two different spark plugs, but E3 only has the E3.48 for BOTH of them. But the manufacturers require two separate heat ranges for the plugs. E3 is not able to cover one or both of these heat ranges. Long story short, I read that in addition to spark plug reach, the heat range is the most important characteristic of the plug.

Started looking into various metal characteristics, as well, since the E3 plug is the only plug I've seen to offer a nickel electrode. Funny enough, nickel is actually a "better" metal than platinum. Nickel's melting point isn't as high as platinums, but they should both last long enough. In all this research, I also ran across some other "gimmicky" spark plugs called "Torque Master" plugs, which use a stainless steel electrode. To save you the trouble, stainless steel is a fairly poor conductor of electricity. A few folks on ClubLexus had positive things to say, but on several other forums, others were complaining about the electrode falling off the plug and causing some damage. Not even worth considering.

Don't want this thread to be a bunch of unsubstantiated claims and opinions, tho. So here are the numbers for a few common metals used on spark plug electrodes. Doesn't include copper, but we already know copper is the "best" choice for conductivity that doesn't run $1,600 an ounce.

http://www.sparkplugs.co.uk/pages/technical/iridium_spark_plugs.htm
iridium_properties.jpg


Soo... my final conclusion is:

That the BEST for performance is copper.
And the BEST for longevity is iridium.

Now, for iridium.... I'll also mention that NGK and Denso are perhaps the "best" manufacturers. Each of them have two separate iridium plugs -- 1 for performance (30k miles), 1 for longevity (120k miles). NGK's 120k mile plugs are called "Laser" Iridums. Denso's 100,000 mile plugs are called "Long Life" Iridiums.

Some people who compare these two manufacturers state that NGK's plugs last 4 times longer, and that Denso's plugs have the "fine wire" 0.4mm electrode [or vise versa]... but they both have comparable plugs - performance and durability.

If your car calls for platinum plugs, I would ditch them and use the iridium plugs for the next 10 years without worrying about fouled plugs. The Long Life & Laser Iridiums actually have platinum ground electrodes, so in terms of electrical resistance and such, they will provide OEM results.... they'll just last 4 times longer without fouling or needing gap adjusted, etc.

But if you're looking for performance... you cannot beat some el cheapo copper plugs. Better to replace them every year or two if you have a ratchet and a spark plug socket.
 
Copper plugs don't have a copper tip, the tip is steel. The copper is up inside the ceramic portion.
 
I would look into denso or ngk I don't know what your application is but I've always used either denso PR ngk with good results. Denso being my plug of choice.
 
Originally Posted By: OVERKILL
Copper plugs don't have a copper tip, the tip is steel. The copper is up inside the ceramic portion.

Hmm... well, in that case... I would think that iridium should be a no brainer.
 
Originally Posted By: grndslm
Been doing some research. Started out looking up info on the E3 spark plugs because I've actually had good results with them in 1-cylinder motors (bicycle motors, lawnmowers, & such)... but I soon discovered that the makers of the E3 plugs are actually pretty small and are more than likely NOT able to offer you the proper plug for your vehicle. For example... was looking at spark plugs for two of my cars, and Denso offers two different spark plugs, but E3 only has the E3.48 for BOTH of them. But the manufacturers require two separate heat ranges for the plugs. E3 is not able to cover one or both of these heat ranges. Long story short, I read that in addition to spark plug reach, the heat range is the most important characteristic of the plug.

Started looking into various metal characteristics, as well, since the E3 plug is the only plug I've seen to offer a nickel electrode. Funny enough, nickel is actually a "better" metal than platinum. Nickel's melting point isn't as high as platinums, but they should both last long enough. In all this research, I also ran across some other "gimmicky" spark plugs called "Torque Master" plugs, which use a stainless steel electrode. To save you the trouble, stainless steel is a fairly poor conductor of electricity. A few folks on ClubLexus had positive things to say, but on several other forums, others were complaining about the electrode falling off the plug and causing some damage. Not even worth considering.

Don't want this thread to be a bunch of unsubstantiated claims and opinions, tho. So here are the numbers for a few common metals used on spark plug electrodes. Doesn't include copper, but we already know copper is the "best" choice for conductivity that doesn't run $1,600 an ounce.

http://www.sparkplugs.co.uk/pages/technical/iridium_spark_plugs.htm
iridium_properties.jpg


Soo... my final conclusion is:

That the BEST for performance is copper.
And the BEST for longevity is iridium.

Now, for iridium.... I'll also mention that NGK and Denso are perhaps the "best" manufacturers. Each of them have two separate iridium plugs -- 1 for performance (30k miles), 1 for longevity (120k miles). NGK's 120k mile plugs are called "Laser" Iridums. Denso's 100,000 mile plugs are called "Long Life" Iridiums.

Some people who compare these two manufacturers state that NGK's plugs last 4 times longer, and that Denso's plugs have the "fine wire" 0.4mm electrode [or vise versa]... but they both have comparable plugs - performance and durability.

If your car calls for platinum plugs, I would ditch them and use the iridium plugs for the next 10 years without worrying about fouled plugs. The Long Life & Laser Iridiums actually have platinum ground electrodes, so in terms of electrical resistance and such, they will provide OEM results.... they'll just last 4 times longer without fouling or needing gap adjusted, etc.

But if you're looking for performance... you cannot beat some el cheapo copper plugs. Better to replace them every year or two if you have a ratchet and a spark plug socket.


Thanks for the write up. Your comments are informative and correct.
 
First of all, the best plug is the one that meet all the requirement of the car's design, that is heat range, firing voltage, durability, and firing orientation (double platinum or reverse platinum for waste spark in some cylinder).

Then, for some of the cars that has sensitive electronics to measure mis-firing, it is important to use plugs that are calibrated or close enough to the calibrated design of the OEM.

Then, it is important to choose a supplier that do not screw up the manufacturing and have good quality control. A plug that is designed right is no use if it is defective from the factory.



When all the above condition is met, you can start playing around with exotic material plugs, extending its life, finding an exotic "fine wire plug" that reduce your firing voltage (narrow tips is very easy to fire), indexing the plugs, etc etc.

A tiny difference in the metal's resistance is nothing compare to the difference in firing voltage caused by the difference in tip size. As long as you do not misfire you will not notice much differences, and most exotic material plugs have finer tip as it can tolerate higher temperature, and that finer tip is what makes the performance benefit by reducing misfire.

Also some of the plugs are now made with "Heat-Active" alloy that has different melting point than bare nickle/platinum/iridium, so the information on the chart may not be that useful as many plugs use alloy in the electrodes.
 
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Originally Posted By: OVERKILL
Copper plugs don't have a copper tip, the tip is steel. The copper is up inside the ceramic portion.


Don't all plugs have copper inside the ceramic portion.
 
Last part from OP:
But if you're looking for performance... you cannot beat some el cheapo copper plugs. Better to replace them every year or two if you have a ratchet and a spark plug socket.

Well that is real news to me, because non OEM plugs cause no end of problems when fitted to some cars. Just try asking on a Volvo forum what happens if you don't fit Volvo plugs to a T4, or ask on a Porsch forum about their expensive plugs.
Some cars just love NGK or Bosch, but the aftermarket copies just don't match up for others, so OEM plugs are best, replaced according to the service interval or any check engine fault codes.
 
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Thermal conductivities, for reference:
(watts / centimeter * kelvin)


Zinc = 1.16
Aluminum = 2.37
Copper = 4.01
Steel = 0.70 - 0.82
Platinum = 0.716
Iridium = 1.47


More proof that copper is an awesome choice for the core of the plug.
 
Originally Posted By: Topo
Originally Posted By: OVERKILL
Copper plugs don't have a copper tip, the tip is steel. The copper is up inside the ceramic portion.


Don't all plugs have copper inside the ceramic portion.


No, a resistor plug is full of carbon.
 
Originally Posted By: OVERKILL
Originally Posted By: Topo
Originally Posted By: OVERKILL
Copper plugs don't have a copper tip, the tip is steel. The copper is up inside the ceramic portion.


Don't all plugs have copper inside the ceramic portion.


No, a resistor plug is full of carbon.


Thanks.
 
Platinum or copper NGK only for Saabs. You start carrying on about iridium spark plugs in a Saab forum and they'll run you out on a rail...
 
Originally Posted By: skyship
Last part from OP:
But if you're looking for performance... you cannot beat some el cheapo copper plugs. Better to replace them every year or two if you have a ratchet and a spark plug socket.

Well that is real news to me, because non OEM plugs cause no end of problems when fitted to some cars. Just try asking on a Volvo forum what happens if you don't fit Volvo plugs to a T4, or ask on a Porsch forum about their expensive plugs.
Some cars just love NGK or Bosch, but the aftermarket copies just don't match up for others, so OEM plugs are best, replaced according to the service interval or any check engine fault codes.

I'm going to be putting some NGK "laser" or Denso "long life" iridiums in my Volvo. It's not a T4, but when I checked the plugs (which are supposed to be 3-prong, platinum plugs). last week... all of the electrodes were rounded off, so the platinum coating must have come off to reveal the copper core?? Just looked at some pics of the OEM plugs, and the color of the electrode looks the same, so maybe the platinum is just on the 3 ground electrodes?? (which would actually make sense)

Either way, the coating is the final "bottleneck" of conductivity / resistance. If the ground electrodes are all platinum, it wouldn't matter at all if the core is copper or actually ALL platinum. This is why, in terms of performance, it would seem to me that the following plugs would be listed from best to worse...

(1) fine wire iridium-iridium (30k mile range)
(2) nickel (??? mile range)
(3) steel (??? mile range)
(5) thicker iridium-platinum (120k mile range)
(5) platinum-platinum (30k mile range?)

If it has platinum, it's tied for worst place in terms of performance. Steel MIGHT actually be worse, but "steel" is a very broad term... but we'll presume that the steel chosen for spark plugs was chosen for optimum levels of conductivity / resistance.

Perhaps this is why I have actually experienced good results with the E3 plugs, and they have actually performed better on dyno tests. They still do not provide optimum heat range for all automobiles, however... so I'd be very careful about putting them in any car. But why choose E3 plugs, anyway... when you can get iridium-iridium plugs??
smile.gif


If a Volvo calls for platinum plugs, like mine... iridium-platinum should perform the same as stock, only lasting 4 times as long.

Originally Posted By: dparm
Thermal conductivities, for reference:
(watts / centimeter * kelvin)


Zinc = 1.16
Aluminum = 2.37
Copper = 4.01
Steel = 0.70 - 0.82
Platinum = 0.716
Iridium = 1.47


More proof that copper is an awesome choice for the core of the plug.

How many plugs DON'T have a copper core, tho??

I haven't seen a copper-coated ground electrode yet... so copper is NEVER the point of least resistance. The core - copper or otherwise - is a non-factor.
 
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Next time you have a spark plug handy, grab a multimeter and actually *measure* the resistance of the core. I did. It is around 4000 ohm. Typical length is 3 inches. Logic tells me that the choice of metal inside makes no difference when you are talking about 4000 ohm resistance.

But some people don't understand the logic but fall prey to marketing.
 
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Originally Posted By: Vikas
Next time you have a spark plug handy, grab a multimeter and actually *measure* the resistance of the core. I did. It is around 4000 ohm. Typical length is 3 inches. Logic tells me that the choice of metal inside makes no difference when you are talking about 4000 ohm resistance.

But some people don't understand the logic but fall prey to marketing.

Engineering is not about designing tools around one value. It's about finding the best trade-offs among ALL values.

Performance is performance, even if small gains in performance must sacrifice 20x plug life.

I *know* there's something to E3 plugs in 1-cylinder engines, for example... and there's some type of data to back it up. Video 1 and Video 2.

But, like I said earlier, E3 cannot meet the optimum heat range for both of the engines that I'm interested in putting them in... so I'd rather not put them in at all. I prefer the diamond shape. But my Volvo takes platinum plugs, stock... And the Corolla takes iridium-platinum plugs, stock... so the iridium-platinum plugs are likely what I'll stick with (since 'm guaranteed the proper heat range, for starters), since there will be absolutely ZERO difference realized in ignition timing and such.

Changing from platinum to steel or nickel could advance timing slightly, which is why people claim that their cars like copper plugs.

Or changing from iridium, steel, or nickel plugs to platinum could retard timing slightly.

Most people just see copper, platinum, or iridium plugs when ordering them from RockAuto.com however. That site distinguishes neither between nickel and steel (much less the quality of nickel and steel used), nor between iridium-iridium and iridium-platinum. This could very well be why most people experience misfires when trying non-OEM plugs. They'll typically be getting the heat range correct, so that is only an issue with the "novel" plugs.
 
grndslm,

I think there are many here who are engineers, or at least have taken some electrical engineering courses about dielectric break down and arcing, which is what this subject is about.

The "material" of the plugs are only different by the tiny disk on the tip whether it is the platinum, iridium, or steel/nickel. This tiny amount will not make a huge difference compare to the rest of the length and volume of the material that are all the same whether it is the copper core or the steel/nickel electrode body. As Vikas mentioned, 4000 Ohms is huge and cannot be due to the metal conductor (which would make up less than 10Ohms) but rather a build in resistor elsewhere (likely to suppress resonance and noise).

The firing voltage is dictated by the air gap, surface (tip) size, and the dielectric material (air fuel mixture). The conductivity of the plug has nothing to do with the firing voltage. As long as it fire, it would ignite the fuel, the amount of current after firing would be influenced by the resistance of the plug, but since it already fired, it serves its purposes of igniting the fuel regardless of how high the current of the arc.

So the goal should still be to reduce the firing voltage to reduce misfire, and exotic plug works well with more heat tolerant metal so you can reduce the tip size further, or you can increase the gap size (last longer) and ignite the air fuel mixture faster.
 
The same holds true for spark plug wires. I don't think I have any more in my stash but there too having exotic wiring material is not going make any difference as the resistance is quite high and those carry miniscule amount of current. Don't let somebody bamboozle you with skin effects etc on the spark plug wires!

It does bug me when people refuse to do simple testing before believing in junk marketing.

For example, if the smoke show from Seafoam is really cleaning your engine, then if you do the exact same procedure next week, there should be zero smoke.

Another example is the mileage gains observed from using a miracle additive. People say they observed 2 mpg gain but when asked if they have ever kept track of their mileage for a long time, the answer is always no. The standard variation is usually more than the observed gains and thus it is just an experimental noise but it is hard to convince people who are unfamiliar with statistics.

In life if you are not logical, rational, and do not have some understanding of statistics, you would be always at a disadvantage.
 
Originally Posted By: Vikas
Next time you have a spark plug handy, grab a multimeter and actually *measure* the resistance of the core. I did. It is around 4000 ohm. Typical length is 3 inches. Logic tells me that the choice of metal inside makes no difference when you are talking about 4000 ohm resistance.

But some people don't understand the logic but fall prey to marketing.


Ohhh can't be, common sense approaches aren't allowed on BITOG...

I agree, a little increase or decrease conductiveness doesn't mean squat when were talking about resistor plugs with 4K ohm internal resistance, plus there is the resistance of the plug wires(if they are used)... Best would be the type with least amount erosion...
 
Originally Posted By: TFB1
Ohhh can't be, common sense approaches aren't allowed on BITOG...

I agree, a little increase or decrease conductiveness doesn't mean squat when were talking about resistor plugs with 4K ohm internal resistance, plus there is the resistance of the plug wires(if they are used)... Best would be the type with least amount erosion...


wires resistance is in the single digit to 1X ohms level, when adding to the resistance of the plugs, it is rounded off to 0.

Adding a "ground shield" to wires is a big no no. Magnetic field between the "shield" and the core would gradually degrade the silicone skin and break it down.
 
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