Iridium Spark Plugs

[steve2006]

I read an article today regarding potential problems with some iridium tipped spark plugs in that the iridium tip comes off ( this stuff is extremely hard and therefore difficult to attach) and falls into the cylinder resulting in potential engine damage.

There is no mention of specific manaufacturers but I would suggest only buying known branded makes.

[E910]

Never heard of a NGK or Denso iridium plug failing like that so my guess would be cheap stuff. I've personally been using the NGK IX range in my vehicles since it was release about 9 years ago & sold hundreds of IX plugs with out any issues. Mind you the IX range only has an iridium centre electrode. The laser range has an iridium ground electrode as well. Stick to the IX range & you'll be safe.

The iridium tips are so small the damage it would cause would hardly be noticeable I would imagine. In theory if it fell off it would just get fired out the exhaust.

[MeisterR]

I use NGK myself... the tip that falls off are Denso as they are very small 0.4mm.

It happen more on high boosted engine such as the RB26 on the GTR... had a few guy lost an engine because the tip drop off from the Denso Plug.

The NGK iridium plug have a 0.7mm tip, and these seems to be much stronger and really haven't heard of them dropping a tip.

[E910]

I think I may have found an answer why Denso plugs fail. Most people assume all iridium plugs are long life. NGK iridium IX last 60K km, Standard Denso iridium last 100K but Denso iridium Power are only good for 20,000 km

That makes them a very expensive plug compared to the NGK equivalents.