NGK XR5 vs NGK XR5Ix Spark Plugs

[lookin@my68]

Anyone tried using the NGK XR5ix Iridium Plugs? 

I know many of you guys use the XR5's

Is there much difference between the two? The Iridiums are very pricey - is it worth the extra?

[Rocky]

I just go with cheap plugs and replace them every year.

[Rocky]

Please allow me to pontificate.  If you go to the www.partsamerica.com website, which is Kragen for the West coast.  And look up the spark plugs for a 1968 Dodge Charger R/T with a 440 engine you will be met with the some of the following possibilities for spark plugs:

Autolites:  $1.24 each.          2 year rreplacement warranty

Champion: $1.49 each.          1 year replacement warranty

AC Delco:  $10.99 each.        3 month limited warranty

NGK Iridium: $10.99 each.      3 month limited warranty

Let's start with prices.  The Autolites are nearly 8.9 times cheaper than the premium plugs.  Their REPLACEMENT warranty is 8 times longer than the premium plugs LIMITED warranty.  If we were to erroneously take those two numbers to make a statistic, that would make the Autolites a better value by a factor of 71.2 times, by assuming that performance is the same.  However;  there have been a few articles in the magazines that tested the "performance" of these plugs.  During these tests, brand new plugs were placed in engines in back to back dyno tests.  In 400+ HP motors, the "performance" plugs tend to add between 1 and 2 HP.  That equates to about a 00.25% and 00.50% gain in power.  Those figures are only attainable for new "out of the box" plugs.  There is no credible test for thousands of miles of use.
   Allow me to use NGK's own words for my next point:
     "NGK Iridium IX spark plugs represent the ultimate evolution of spark plug technology and performance. Iridium is significantly stronger than any metal used in spark plugs today. It's also the hardest metal used (in fact, iridium is 6 times harder than platinum) which has allowed NGK engineers to design an ultrafine center electrode reducing the voltage requirement for spark."

This quote is from NGK's  $2.99 V-power plug:
    "The V-Power plugs also are highly durable against electrical and chemical wear, making them a long-life replacement plug. They enhance ignitability, lower the voltage requirement of ignition systems, and have strong anti-fouling characteristics, while improving fuel mileage and acceleration performance. Because of the V-Groove, the spark occurs at the edge of the center electrode. So heat is not absorbed by the electrode itself ("quenching effect"). This allows the flame kernel to expand quickly and efficiently for a complete burn and great performance."

The only semi-credible claim in these two quotes is that they LOWER the voltage requirement of ignition systems.  It also looks like that they figure that because iridium is 6 times harder, they only need to use 1/6 as much of it.  Now that's all fine and dandy for commuter cars, but we want performance, so most of us put on stronger coils for more spark.  Is anyone seriously going to buy these plugs at over 10 bucks a piece and not spend the extra 10 bucks for a coil that is 50% stronger?

And finally, would you rather buy brand new cheap plugs every year or keep these fancy plugs for the next 9 years?

     Just my view,
         Rocky

[lookin@my68]

Thanks Rocky, - a very well put poste!