Question for the duratec owners

[GWise]

I am trying to assist someone with some research on a racing mzr and I had a quick question for you duratec folks.

Do your spark plugs have tapered seats or washers?

Also, what plugs do you prefer? He has had good success with denso iridium racing in the past, but it seems only denso iridium power are available for the mzr.

[Sean]

Page 17 of the most recent Cosworth Duratec catalogue that I have seen (2009/2010 edition) lists three plugs:
NGK Spark Plug BR7EFS - Heat Range 7
NGK Iridium Spark Plug TR7IX Duratec - Heat Range 7
NGK Iridium Spark Plug TR8IX Duratec - Heat Range 8

Cosworth supplied my engine with BR7EFS, but I changed them to TR7IX. No issues so far, although my car is not raced.
Installation torque is 12Nm, and gap is 0.64mm (0.025") per Cosworth recommendation.

Lots of Duratec info available from the CSR forum that may apply. Following is a link to the spark plug thread specifically:
CSR forum spark plug thread


edit -- I cannot recall whether tapered seats or washers just now.

edit 2 -- More useful plug info at sparkplugs.co.uk. This page seems to suggest that both plugs I have used do have tapered seats, assuming I have decoded all that mumbo-jumbo properly.

[GWise]

Thanks Sean, You're as helpful as usual.

Did you notice a significant improvement with the NGK's?

[Sean]

Hard to say, as I changed plugs the day before the last dyno session. There was a significant improvement, yes, but impossible to say if the plugs were a significant contributing factor.

Thanks Sean, You're as helpful as usual.

Still trying to determine if this is an insult or a compliment!

[GWise]

Absolutely a compliment. Thanks.

[moosetestbestanden]

I'm using NGK SP-BR7EFS as recommended by SBD for a high compression engine. I can't remember whether they're tapered or not.

[Sean]

Bought some fresh plugs for the Duratec recently, and learned of a few new developments. According to the clerk at my friendly neighborhood auto parts place (Winchester Auto), NGK no longer makes the BR7EFS, but the BR7EF is a direct replacement. Looking at their code sheet, it seems their is only a minor difference in the firing end construction. Additionally, NGK (or their retailers?) is no longer referring to their plugs by their part numbers, but instead is using their "stock numbers". Why, I don't know.

Part no. BR7EFS is stock number 1094
Part no. BR7EF is stock number 3346

REF:

NGK part number to stock number cross-reference sheet PDF file.

NGK part number code reference sheet PDF file.