Iridium Spark Plugs

[Errtt]

Couple years ago I changed one of the motorcycles to NGK IX. I noticed fast start on winter cold mornings and smoother running right after start. That sold me right there.
So now all 3 vehicles and 2 motorcycles have the NGK IX.

I don't track my MPG, but have since heard others say their motorcycle also starts better, smoother, and a few say better MPG.

 

[Vikas]

NGK Laser Platinum @ 152K 10 years

Closeup of the two plugs

 

[Kaboomba]

Great pics, fascinating. Thanks for sharing that.

 

[Vikas]

That is why I like to stick with the OEM plugs. In general, the car manufacturer knows which plugs works the best for that particular engine.

Also most coil on plug systems have huge margins and can fire the plugs even when they are completely worn out! Here is an example which has 10 years & 141K on it. Notice the huge gap; it is almost the three times the specification. The car was running fine when I swapped them.

 

[rshunter]

Originally Posted By: zmelli
Construction of NGK and Denso plugs is similar for the most part, the big difference being Denso's use of a 0.4mm Iridium tipped centre electrode - claimed to be the world's smallest production centre electrode, where NGK's IX centre electrode is 0.6mm. As with NGK Iridium, and indeed most other spark plugs, the narrower the centre electrode is, the lower the potential difference (voltage) that is required to jump the gap between centre and ground electrodes. It follows that the Denso plug will require an even lower 'spark jump' voltage than the NGK plug. The Denso plug also utilises a 'u-grooved' ground electrode which is claimed to aid in the production of a 'flame core' which further improves the combustion process. In theory, all the benefits offered by NGK Iridium plugs are further improved by the Denso Iridium plugs - with the exception of service life. The smaller diameter of the Denso centre electrode means that less wear can take place before the plugs' optimum service life is exceeded.

Denso also manufacture long life Iridium power plugs such as SVK20RZ8, VK22PR-Z11 etc. These maintain the 0.4mm Iridium centre electrode but also have a platinum 'chip' in the ground electrode to allow performance to be maintained for a much longer service life (up to 60000 miles). These plug types are usually recommended for high power turbo charged engines where wear may otherwise be accelerated.

Only the Denso Iridium Power plugs have the 0.4mm center electrode, as well as a U-groove ground electrode. The Denso Iridium Long Life plug is equipped with a 0.7mm center electrode. The Iridium Power has a 30K mile recommended replacement interval. Iridium Long Life is recommended for up to 120K miles.

The primary difference between the NGK Iridium IX and the NGK Laser Iridium is the Laser's use of a platinum disc ground electrode for longer service life.

Personally, I'd use the Denso options whether aiming for power or endurance. Though the reality is that, at least in the long-life variants, there really isn't a lot of difference. This is reinforced by the fact that many a Toyota or Lexus owner will find that one cylinder bank of their engine is fitted with Denso, while the other bank has NGK.