I picked up a set of the standard copper 7ES NGK variety that most VIII owners claim - and found the thread stems are short compared to the stock IXs plugs.

I've done a lot of searching and come up with a lot of nothing for the IX. Is there a copper NGK thats one step colder and fits in the IX?

I also thought the head was basically the same. I suppose the IX plugs sit deeper in the CC.

 

Yes I think the plugs are longer for the IX's

 

yes they are different (longer), plug for the VIII wont work on a IX and visa vesa.

 

Yes the threading portion is longer(meaning more threads) for the IX. However, they arent interchangeable.

 

As of right now the only thing i have used in my car and that i actually know works is the stock NGK ILFR7H Iridium Spark Plug. The place i know you can get the from is the dealer but they are expensive as sh*t, like $60 for 4. I'm sure there is another place to get them but that is where i went when i had to replace mine cause they are right down the road from me.

 

There is a thread with a list of the three NGK plugs that fit the IX. Use the plug number in the post above and you'll be able to fidn the other thread easily.

 

AH - that helped on the search.






NGK ILFR7H (OEM) Iridium
http://www.sparkplugs.com/more_info.asp?AAIA=&pid=20451

NGK LFR7AIX Iridium
http://www.sparkplugs.com/more_info.asp?AAIA=&pid=16602

HKS Part number: S40iL

Step colder= NGK R7437-8 Stock #4901

2 Steps colder= NGK R7437-9 Stock #4654

3 Steps colder= NGK R7437-10 Stock #4655


The AIX plugs being for a Subie STI - they work and cost $8 - I havent confirmed that, tho.


There is a company out west - Monarch - who sells NGK plugs. I'll see how much they R7437-8s cost.