Bonneville America Forums Forums Technical Forums General Tech Iridium v.s. OEM Spark Plugs.....

Any opinions on this subject? Does the average riding that most of us do benefit from a $20 pair of plugs?

Given, the Iridium should put out a much stronger spark, thus better fuel burn, but do they last longer than standard plugs?

BB,I have read nothing that said they put out a much stronger spark?I do not believe the spark plug can amplify the spark?Would it not have to be a Capasitor or coil to do that?What I have read is that the smaller tip puts less overall demand on the ignition system,which I guess means it has less resistance than a regular spark plug?I also believe that the material has a longer service life.I think that is about it.The electronic guru's on the board should be able to enlighten us about this stuff.I am not a big fan of super duper wammy jammy spark plugs,but when I read that the plug puts less demand on the ignition system my ears perked up!Watch how the counter people handle the spark plugs at your local auto parts store.I have seen counter kids grab loose individually boxed spark plus and drop em in a bag. I hand em right back to em and instruct them to get me another set and gently put them in a bag.Stupid kids think they are handling a bunch of nuts and bolts. Spark plugs are not made to take shock impacts. You can hairline crack the insulator and that plug is junk.So if you and I buy a set of twenty dollar plugs, watch how they are handled. Al

Snake oil.

Put the extra money in fuel and take a nice ride. They ain't worth it.

Due to the properties of Iridium, the spark plugs centre electrode can be made with a much smaller diameter than with platinum, Gold or gold palladium and copper/nickel types without sacrificing service life. The spark plugs potential difference is more concentrated at the tiny Iridium tip and hence less 'spark jump' voltage is required - this can be as much as 5,000 volts less than with standard plug types. Ignition is improved and less strain is placed on the ignition system. Benefits of improved ignition/combustion include better fuel economy, increased power/acceleration and especially better throttle response.

Of course, that's from this UK spark plug page... not me.

As I suspected.... thanks for your responses!! Now... has anyone got alternatives to the NGK's (i.e. AC, Champion, etc.)?

Spark plug cross reference spreadsheet link on this page.
Do a 'ctrl f' and search for DPR8EA-9. Then look across and find the matches.

Stopped by Pep Boys just to see what the IR plugs were selling for. Holy -hit Batman,$15.99ea, comes in a box of four plugs, not to be split open!!! So they are still sitting on their shelf. Al

The fine wire type of aircraft plugs use a pair of indium wires fir the ground electrodes. However, the wonderful spark you get for a short time from splitfire plugs proves the theory that all you need to get a good spark is a couple of sharp edges close together. And, you can buy a lot of cheap Champion or Autolite plugs for 20 bucks and file them once in a while to keep the edge.

Quote:

---

I do not believe the spark plug can amplify the spark?Would it not have to be a Capasitor or coil to do that?

---

During the '70s and the advent of HEI ignition systems, I was working at an Oldsmobile dealer. The plug gap spec was for .080. Combined with resistor wires it made for a very hot, short duration spark. The idea being that the coil had to produce more voltage, up to 40,000 volts, to bridge the resistance. Of course the coil has to be capable of producing the requisite voltage. So the answer is no, the plugs cannot amplify spark, they are only part of a tuned system.

BB, I got one of them there HEI systems in my old 76 Vette. Running a .050 Gap on the plugs,but only after I put one of the high output coils from MSD or Mallory(can't remember which)in there. Darn HEI does not funtion very well at low RPM's though. If I putzs around at low rev's for any lenght of time,it fouls my plugs right up. Give me an old dual point distriutor and Mallory HO coil anyday. Shoulda bought a little bit older Vette,say maybe a 63? Al

Quote:

---

Give me an old dual point distriutor and Mallory HO coil anyday.

---

You got that right. HEI will not self clean fouled plugs, and low speed putzing is what fouls them. Changed a lot of fouled plugs back then, paid one hour flat rate and took about ten minutes.

Guys, do a web search for NGK Plugs. There are lots of places out there that sell them for less than places like Pepboys. Parts411, has them for $2.36 EACH!!!! Here's the link, so far they have been OK to deal with.

NGK Plugs at Parts 411

What I can tell you, is that it does matter in my car. For the VW 1.8 Turbo engine, there are 2 engine codes, even though both put out identical HP and Torque figures, have the same valvetrain, compression ratio, etc... But for some reason, one is mapped with the Engine Management system and Ignition system to use ONLY the NGK DPR9EA-9, while the other has another NGK Plug OR an Autolite plug, both for about $2.50 each! Mine were $25 each at the dealer although I finally found them online for $11 each, still a BIG hit when talking about a 4 cylinder. I tried the Autolite plugs recommended for the other engine code thinking there is NO way it could make a difference, BUT it DID! Within 30 minutes my Emissions warning light came on and stayed on. I put the old plugs back in, and again, within 30 minutes, the warning cleared up. Our bikes aren't so sensitive since they don't have all the feedback controls (Oxygen Sensor, Cats, and an ECU), so we could probably live with an alternative plug provided it has the same heat range as ours, but boy what a pain. I just found the plug I need on my car though at Parts 411 for $2 something each, so I am now a MUCH happier camper!!! Where were they 2 years ago when I paid $44 for spark plugs?

I priced our OE NGK plugs this evening at $1.59/ea at OReilly Auto Parts.

The Iridium NGKs were only $6/ea. I couldn't believe it, so I left with neither! Had to come do a little research here, and on the NGK site. Ran the application and it is the correct part number.

So, for $6/plug, would the Iridium plug be worthwhile?

Alan, for your old 'Vette, get one of those replacement high performance aftermarket HEI modules. For years, the only thing available was an obscure Olds HEI module, but the hot rod guys finally came up with a better-than-stock replacement.

Circle track guys use them when they are restricted to "stock" ignition systems. You wouldn't need an MSD 6 box for driving on the street with this improved HEI module.

You can use an MSD-6 box triggered by the stock HEI module, but you are still stuck with the poor performance of that module at higher rpms.

There are also remote mounted coil change over kits for GM's HEI distributor. MSD and Accel make them. And a nice aftermarket dist. cap is a good idea, too, as the stock cap has a nasty tendency to burn through right in the center, where the rotor contact is.

A good stock replacement distributor is an older 'Vette electronic one, which uses the older, small Chevy cap. Use one of those to trigger an MSD 6 box. These older 'Vette distributors also have a mechanical tack drive provision, if you need that.

Top off your ignition upgrades with a good set of plug wires, such as Mororo Heli-coils, or a Magnecor set.

One of the benefits of these "fancy dan" spark plugs is that they last longer. Problem is, a steel threaded plug sitting in an aluminum head for a long time can become seized. Ask any old air cooled flat 4 engine VW mechanic!

Be sure to use a dollop of never-seize thread lubricant to prevent stuck spark plugs.

Having said all that, what is more needed is a high performance replacement ign. box. Race Dweeb up there in Michigan has been trying to come up with one to sell, but so far, no luck.