SP spark plugs

mazlot · Postby **mazlot** » Sat Jan 03, 2009 3:27 pm

What are your recommendations ?

Daz · Postby **Daz** » Sat Jan 03, 2009 4:05 pm

I think the popular choice is (NGK) BKR7E11, the 7 has something to do with temperature and I think the stock ones are 5. I changed mine over to this model in iridium years ago and they seem good... no issues.

blackster · Postby **blackster** » Sat Jan 03, 2009 6:32 pm

Daz wrote:I think the popular choice is (NGK) BKR7E11, the 7 has something to do with temperature and I think the stock ones are 5.

The heat range refers to how much heat a spark plug is capable of removing from the combustion chamber. A spark plug with the proper heat range will insure that the tip will maintain a temperature high enough to prevent fouling yet be cool enough to prevent pre-ignition.

bigdog · Postby **bigdog** » Sat Jan 03, 2009 7:03 pm

6's are the standard SP plug, most of us run the 7s, if you've upped the boost you can run 8s - Dave uses these in his. 5s are way too hot a plug for an SP. As I understand it from the dyno tests done on MX5s there is no performance benefit in running iridium plugs, just a longer plug life. Given the cost I would go (and have) the BKR7E11 route and change them more often.

Garry · Postby **Garry** » Sat Jan 10, 2009 10:54 pm

What they said, 7's, though Mazda will probably want you to fit 5's or 6's.

Woo · Postby **Woo** » Sun Jan 11, 2009 12:07 am

Depends on the boost you're running.
6's are good with a good tune (ie standalone), otherwise 7's for up to 15 psi. You may need to close the gap if you run 7's (0.7 mm).
If you're running bigger boost go for the 8's but as suggested check for fouling (0.7-0.8mm)

Bazz