Spark plugs
 

which are best for B20b?

I recall that NGK BP9HS are the recommended type from memory, but I fitted Accuspark Iridium plugs into my B20 144 last year and found starting and running so much better. Here's a link:

http://accuspark.co.uk/plugs.html

Paul.

I think you may have inverted the number. NGK heat range 9 is way too cold. NGK BP6HS or BPR6HS (resistor) is the recommended plug. If you do a lot of high speed cruising you can go one step colder to a BP7HS; but, they will not last as long in urban driving. If you go with the 6 heat range you can run the NGK BPR6HIX which is an Iridium plug. That is what I am running in my B20E and I have been on the same set of plugs since 2016, although not a whole lot of kms in that time because the 142 is a fair weather car.

The iridium are resistant to fouling and will generate a spark at a lower voltage than a conventional fat electrode plug so starting may be improved when the voltages drop during cranking. The iridium electrode is also more durable than the conventional electrode which is why they are used in cars with extended maintenance intervals. Purchase from a reputable vendor because there are NGK iridium EBay fakes on the market. They look correct; but, the center electrode is not iridium so they burn up rather quickly.

You are of course correct, I was thinking 6 but somehow typed 9, glad you agree that iridium plugs are a benefit, thanks.

The volvo ones you should still be able to get from the dealer are the best.

there are many fake NGK plugs on line !

Thanks for answers