Iridium: Hype or not?

[MN]

There sure is a lot of talk about how Iridum spark
plugs need lesser voltage, improve fuel efficiency
(up to 3%!!!!), last longer, give more horsepower,
better acceleration, etc., but is any of this true?

Split-fires were supposed to do all this and more,
I never noticed much difference

The one thing that I am prone to believe is the
longevity issue but then I can't find any recommendations
for extended change intervals which makes me doubt
the whole Iridium thing as mostly hype.

My Subie with NGK regulars is due for new spark plugs.
Any suggestions would be greatly appreciated.

MN

 

[SmokedMeat]

You can also check for E3 Spark Plugs. I think they're EPA approved.
Anybody ever tried them?

http://www.e3sparkplugs.com/

 

[Edward Hayes]

I just replace with what was in the car when new. For me it was NGK
standard.

 

[Rat]

There sure is a lot of talk about how Iridum spark
plugs need lesser voltage, improve fuel efficiency
(up to 3%!!!!), last longer, give more horsepower,
better acceleration, etc., but is any of this true?

Split-fires were supposed to do all this and more,
I never noticed much difference

The one thing that I am prone to believe is the
longevity issue but then I can't find any recommendations
for extended change intervals which makes me doubt
the whole Iridium thing as mostly hype.

My Subie with NGK regulars is due for new spark plugs.
Any suggestions would be greatly appreciated.

MN

Hard to go wrong with NGK platinum plugs. Std equipment on the svx.

 

[Philip Procter]

There sure is a lot of talk about how Iridum spark
plugs need lesser voltage, improve fuel efficiency
(up to 3%!!!!), last longer, give more horsepower,
better acceleration, etc., but is any of this true?

Split-fires were supposed to do all this and more,
I never noticed much difference

The one thing that I am prone to believe is the
longevity issue but then I can't find any recommendations
for extended change intervals which makes me doubt
the whole Iridium thing as mostly hype.

My Subie with NGK regulars is due for new spark plugs.
Any suggestions would be greatly appreciated.

MN

Don't know if it's true, but I read a piece from the company that
makes the capacitor plug wires. They recommend silver plugs. According
to them, the iridium and platinum plugs are intended to increase the
replacement interval, not improve the spark quality. They said that
silver is a much better conductor and better suited for plug tips.

Again, no idea if any of this is true.

Comments?

Philip

 

[Rick Courtright]

(up to 3%!!!!), last longer, give more horsepower,
better acceleration, etc., but is any of this true?

They also cure warts, improve your sex appeal, give your laundry whiter
whites, add 50 more channels to your TV coverage, and...

Oops, got carried away there. I'm with Ed: the factory engineers are
faced with the job of finding the best plug for OVERALL usage. So, even
though there MAY be a situation that warrants something special, what
came with the car is probably going to be hard to beat. Unless you just
happen to like to tinker... which I liked to do a whole lot more before
engines which are increasingly being set up where one can't even SEE
where the plugs are, let alone get in there easily! Changing plugs has
gone from "fun to experiment" to nothing but a chore.

Rick

 

[Jim Stewart]

Don't know if it's true, but I read a piece from the company that
makes the capacitor plug wires. They recommend silver plugs. According
to them, the iridium and platinum plugs are intended to increase the
replacement interval, not improve the spark quality. They said that
silver is a much better conductor and better suited for plug tips.

Again, no idea if any of this is true.

Comments?

Yeah. The extremely small difference in resistance
of the various tip metals won't make *any* difference
in performace. At 20-30 thousand volts, the millivolt
drop at the plug tip would be unmeasurable. Simple
Ohm's law.

Total marketing bullshit.

 

[John O]

Don't know if it's true, but I read a piece from the company that

Yeah. The extremely small difference in resistance
of the various tip metals won't make *any* difference
in performace. At 20-30 thousand volts, the millivolt
drop at the plug tip would be unmeasurable. Simple
Ohm's law.

Total marketing bullshit.

Plus, silver is far too soft to survive that environment and an application
where arcs are needed.

-John O

 

[Jim Stewart]

Plus, silver is far too soft to survive that environment and an application
where arcs are needed.

Agreed.

 

[Rick Courtright]

Total marketing bullshit.

I think ya nailed it, Jim!

Rick

 

[y_p_w]

Don't know if it's true, but I read a piece from the company that
makes the capacitor plug wires. They recommend silver plugs.
According
to them, the iridium and platinum plugs are intended to increase the
replacement interval, not improve the spark quality. They said that
silver is a much better conductor and better suited for plug tips.

Silver? There's a disaster waiting to happen. Them problem with
silver is that it oxidizes far too easily at even room temps. And
it would melt down under that kind of heat. There's a reason why
spark plugs typically use nickel alloys/platings for the electrodes
(as well as platinum/palladium/iridium).

Theoretically, annealed crystalline silver is the most conductive
metal available. After that, it's annealled crystalline copper.
Neither of these metals would make for a good spark plug electrode.
Copper and silver might be OK for the plug core where it can be
sealed from any oxygen and where it won't melt down. However - I
can't see the point of using silver when copper is so cheap.

Again, no idea if any of this is true.

Untrue.

 

[l.lichtman]

The important characteristics of the metal used for spark plug
electrodes are high melting point, resistance to oxidation at high
temperature, and electron emission. Resistivity is not a serious
matter, as has been pointed out earlier--the current is quite low, and
the path length is very short.

I recall from the good old days, that vacuum tubes used special
coatings on the cathodes, to improve electron emission. However, with
modern solid-state electronic ignition systems, the voltage available
to fire the plug is so high that these things don't matter as much as
they did in the good (?) old days.

 

[l.lichtman]

The important characteristics of the metal used for spark plug
electrodes are high melting point, resistance to oxidation at high
temperature, and electron emission. Resistivity is not a serious
matter, as has been pointed out earlier--the current is quite low, and
the path length is very short.

I recall from the good old days, that vacuum tubes used special
coatings on the cathodes, to improve electron emission. However, with
modern solid-state electronic ignition systems, the voltage available
to fire the plug is so high that these things don't matter as much as
they did in the good (?) old days.

 

[l.lichtman]

The important characteristics of the metal used for spark plug
electrodes are high melting point, resistance to oxidation at high
temperature, and electron emission. Resistivity is not a serious
matter, as has been pointed out earlier--the current is quite low, and
the path length is very short.

I recall from the good old days, that vacuum tubes used special
coatings on the cathodes, to improve electron emission. However, with
modern solid-state electronic ignition systems, the voltage available
to fire the plug is so high that these things don't matter as much as
they did in the good (?) old days.

 

[Jim Stewart]

The important characteristics of the metal used for spark plug
electrodes are high melting point, resistance to oxidation at high
temperature, and electron emission. Resistivity is not a serious
matter, as has been pointed out earlier--the current is quite low, and
the path length is very short.

I recall from the good old days, that vacuum tubes used special
coatings on the cathodes, to improve electron emission. However, with
modern solid-state electronic ignition systems, the voltage available
to fire the plug is so high that these things don't matter as much as
they did in the good (?) old days.

My nephew collects old spark plugs and
he has a couple that were advertised as
radioactive, presumably to ionize the area
around the electrode to increase electron
emission.

 

[MN]

They also cure warts, improve your sex appeal, give your laundry whiter
whites, add 50 more channels to your TV coverage, and...

Oops, got carried away there. I'm with Ed: the factory engineers are
faced with the job of finding the best plug for OVERALL usage. So, even
though there MAY be a situation that warrants something special, what
came with the car is probably going to be hard to beat. Unless you just
happen to like to tinker... which I liked to do a whole lot more before
engines which are increasingly being set up where one can't even SEE
where the plugs are, let alone get in there easily! Changing plugs has
gone from "fun to experiment" to nothing but a chore.

Rick

Thanks to everyone for their input.

The E3 plugs are interesting but some report
electrical noise with them. Rick's recommendation
for standard NGK's makes a lot of sense (he's made
tons of miles), but I hoped for something that doesn't
need to be changed every 30k, or so. Seems like
NGK platinums is the way to go for me.

MN

 

[David Spektor]

I have Denso IK20 iridium plugs in my MY02 WRX for 17,000 miles.
There was definite improvement in pick-up under the turbo boost conditions,
not much of that in NA mode (in comparison with stock OEM plugs).
There was no noticeable change in gas mileage after switching to iridiums,
if anything- very small drop.
Spark plug replacement happened to be almost 4 hour exercise (because of
tight space and fragile plug coil connectors) what used to be 45 min - 1 hr
on Legacy. So , I am hoping for good longevity of iridiums not to do the
very often. Although stock platinum plugs did not look bad after 30,000
miles...

I am enjoying experimenting with something new: iridium plugs, ceramic
brakes, silicone wipers, but honestly, "old stuff" is just fine for majority
of drivers. New toys bring mostly emotional value to some people, not that
much of functional value..
Just my humble opinion.

Dave.