Confused about Spark plugs hatch sti
 

Need some plugs for my 08sti

Ngk list them as SILFR6A11 which are about £70.00 a set

However I have been told that i can fit ILFR6B which I can get for£32.00 a set (these are listed for impreza's <08)

Anyone know what the difference is apart from the cost?

I have an RB320 which is the same 2.5 engine. I use ILFR 7H. The standard plugs would have been ILFR6B. I have used the colder 7 heat range as im told its better by my mapper. The H is just a more modern centre electrode to the B so wither will do.

So why list a different plug number for the newer cars?
Surely there must be a reason why the hatch plugs are listed as different than the hawks?

I have no idea to be honest mate. As far as i am aware the hawk and hatch share the same engine but with a few differences. I think the hatch has AVCS on the intake and exhaust were the hawk only has it on the intake and twin scroll turbo i believe. Cant see this making a difference to the plugs but i am no expert. My advice would be to phone someone like Enginetuner and ask them. They have huge experience with these hatch cars and are very helpful and forthcoming with advice.

std plugs are ILFR6B
Colder plugs ILFR7H

So I suppose the question is why do NGK bother listing a different plug for the hatch ?

Surley they wouldn't have gone to the hassle of developing a new plug if it wasn't needed?

silfr6a11 is for a 07> 2.0 non turbo. according to my chart

to be honest SILFR6A11 is not a plug number i have ever seen talked about here. Are you sure thats not for a non turbo ?

According to NGK website this is what listed for a >07sti 2.5

http://www.ngkpartfinder.co.uk/car_c...529&engine=2.5

And a <07sti 2.5

http://www.ngkpartfinder.co.uk/car_c...529&engine=2.5

So there does appear to be a different plug recommended for the hatch, wonder what the reason is?

Looks like SILFR6A11 is recommended for all impreza's manufactured after 09/07 maybe it to do with the 60000 service interval for the plugs?

Hatch STi onwards.......................

http://homepage.ntlworld.com/donald....ch%20plugs.JPG

Right done some more digging today and found that NGK SILFR6A as Don mentioned is the correct plug, however NGK no longer list it…

SILFR6A6 is the new part number as it comes pre gapped as you not supposed to re-gap Iridium plugs as easily damaged.

SILFRA11 is the new plug for the non turbo >07

Im assuming the 6 or 11 relates to the pre gapped size.

Hope this helps anyone else…..