Which spark plug?

dorifta · Postby **dorifta** » Fri Aug 21, 2009 5:56 pm

hey all

i went to order some spark plugs from autobarn n they only had bosche stuff left.. so i took watever was right for the mx5...

i took out the current plugs in my nb8a n they are bkr6es? i thought this was a bit odd but are they the right plug to get?

thanks in advance

philz · Postby **philz** » Fri Aug 21, 2009 6:16 pm

NGK BKR5E-11

Should be like $4 each, any auto store should stock them, even those small independent businesses.

dorifta · Postby **dorifta** » Fri Aug 21, 2009 6:45 pm

are bkr6's too cold?

sliq · Postby **sliq** » Fri Aug 21, 2009 7:13 pm

are the NGK Iridium IX over kill? worthwhile spending $18 a pop?

philz · Postby **philz** » Fri Aug 21, 2009 7:42 pm

yes overkill, $18ea is a waste.

Not sure if the brk6 are too cold, but that's what's recommended on NGK site (brk5) I use them, no problems here.

dorifta · Postby **dorifta** » Fri Aug 21, 2009 9:28 pm

They gave me Bosch FR 7 DCX+

Whats the comparison between Bosch and NGK

93_Clubman · Postby **93_Clubman** » Sat Aug 22, 2009 3:55 pm

dorifta wrote:They gave me Bosch FR 7 DCX+

Whats the comparison between Bosch and NGK

i'm not sure if it's proven or why, but the NGK seems to be favoured as better suited to standard or at least reasonably standard MX5s. my NA8 owners manual lists bkr5e11 or bkr6e11 as a recommended spark plugs, along with a couple of Nippon Denso.

rodent · Postby **rodent** » Mon Aug 24, 2009 8:15 pm

Am I right in assuming the 6's would be a better match if you've bumped the timing to 14 degrees or more? Would it still be safe enough to run 91 octane in this configuration?

Wholesale Suspension · Postby **Wholesale Suspension** » Tue Aug 25, 2009 11:17 am

I always use bosch,

I don't rally like the NGK series too much.

Bosch Super 4's for me all the way.

Benny · Postby **Benny** » Tue Aug 25, 2009 3:17 pm

rodent wrote:Am I right in assuming the 6's would be a better match if you've bumped the timing to 14 degrees or more? Would it still be safe enough to run 91 octane in this configuration?

If you've got your timing bumped up, I would be using Premium or 98 RON fuel to protect the engine from pinging.

When your timing is advanced, the chances of pre-detonation increase substantially, so using a higher RON fuel will give you some protection against it.

rodent · Postby **rodent** » Tue Aug 25, 2009 6:06 pm

Yeah with bumped timing I'd always be using 98, but there have been situations in the past where it hasn't been available so I've had to throw in some octane booster which isn't great for the engine in the long run either. But it sounds like using a cooler plug won't help things anyway, oh well. Thanks for the tip George

dorifta · Postby **dorifta** » Tue Aug 25, 2009 6:55 pm

What's this timing cheat? How's it effect fuel economy and lastly can it be done with nb8a?

PUR157 · Postby **PUR157** » Tue Aug 25, 2009 9:10 pm

That would be the "timing bump" "timing advance" it's been described as on this forum
Enter that as a search query and you'll get a little more info

But if I remember right it cannot be done on the later BPs, at least not as easily as the ones found in the NA, as timing in the NA is mechanically controlled
the NB BPs timing are controlled by the ECU?

Have I got that right?

Garry · Postby **Garry** » Tue Aug 25, 2009 10:53 pm

Using a plug one or two steps cooler can help with pinging. That's why SP's should use the bkr7e11. Though Mazda persist in putting in the bkr6e11 when I get my car serviced.