19 replies to this topic

[Jim Venable]

Searched the site and found a few references to spark plugs from last year and the year before.
Searched the web, all kinds of plugs mentioned.
If you don't mind, what plug or plugs are best for Spec Miata?
I'd ask my motor builder but like many of us I don't have one.

Appreciated,
Nice Guy Jim

[FTodaro]

To me plugs are like oil its personal preference, other than the plugs heat range, i doubt that you cold tell the difference between brands.

[davew]

We use (and sell) the NGK plugs and love them. We've installed dozens, and everybody comes up loving them. Simple, effective, done.

This lazyness thing may get to be fun

NGK plugs are cheap and they work. I buy them by the 100's

Dave

[Keith Novak]

NGK plugs seem to have a good lifespan. Bosch plugs have a reputation for being really good out of the box but not for very long. They were recommended for an engine I had a while back but they also recommended changing them after every race weekend. They're dirt cheap though so it's not a big deal.

[Race Engineering]

We run Bosch #4002.

[Keith Novak]

Last set I bought 2 weeks ago they said that P/N doesn't exist anymore. Looked like they changed the color of the box and gave them a new number.

[pat slattery]

We run Bosch #4002.

+1 what Bob says. runs well and cheap

[Race Engineering]

I think your correct Keith, whats the new number?

[Keith Novak]

I used the 6702 which does have some differences now that I compare the two closely. Same heat range, most of the materials are the same but they aren't identical.

[MazdaSteve]

FR8DPX

[Rob Burgoon]

I don't know if I keep getting plugs from a bad batch or what, but I could never get the 4002s to stop sending their ground straps through the exhaust. No problems with NGKs.

[Jim Venable]

Thanks all.
Might someone be willing to share a plug number or numbers for the NGK?

[Ron Alan]

BKR7EIX-11 6988 is what we use...no idea if these are the correct app...was told to use them. Not as hot?

[Keith Novak]

BKR7EIX-11 6988 is what we use...no idea if these are the correct app...was told to use them. Not as hot?

Those are heat range 7. The Bosch plugs Bob recommends are heat range 8. Granted...I don't really know what that means.

[Jim Drago]

I think those are the irridium's, Either work fine. I was using the irridium's for a long time and went back to the standard NGK's as I was changing irridiums when they didn't need to be changed. You can run iridium's all season in most cases. But you can buy a set of teh non irridium plugs for what you pay for one irridium plug.

The NGK plug I run is BKR7E
Jim

[Jim Venable]

Brain fade here. I should have asked if the plug to engine size matters.

Does it?

We run a 1.6.

[Roger Caddell]

Have a buddy that works for NGK (and is a racer as well) so I asked his opinion. He wrote:


"The Iridium will work better through the temperature changes of the motor. Also should see improved throttle response off maintenance throttle. Of course they will live longer but most know that.
Also don't compare heat ranges from different companies. They all use something different to come up with the numbers they use. Bosch is backwards from NGK."

[Bench Racer]

Those are heat range 7. The Bosch plugs Bob recommends are heat range 8. Granted...I don't really know what that means.

Info that may be informative. The info is by NGK with reference to several plug manfactures & they warn that when the manfacture changes an item withinthe plug that the heat range is affected.

http://www.ngk.com/s...- Bosch)&mfid=1

[Steve D]

Dumb question alert: Are our cars sensitive to plug gaps? I am using the NGK Iridiums and re-gapped them to the 0.040 recommended in the shop manual.

[Keith Novak]

Don't know on the NGK but with the Bosch, Bob T said don't even put a gap tool in there to check. Just put them in straight out of the box. Take a look on the box or mfg website too. I have seen some that explicitly say don't change the gap.