Quote from NGK

[DaKidd]

OK, I sent an e-mail to NGK about our setup and running at 10psi. My e-mail is at the top, with his responce at the bottom. I hope this helps in our search for the "perfect plug"!

My e-mail:

"Hello, I have a 2003 MAZDASPEED Protege, and I didnt see anything for that in your "part finder" section for this car. It is a 2.0L DOHC Turbo charged (T-25 Garret running at 10psi). It has platinum NGK PZFR6F plugs in it now (stock). I would like to go with colder plugs (1 range colder). What would be the best plug # for this? I think that the stock plugs are just the wrong type of metal, and the wrong heat range for 10psi boost. I was told that the Copper NGK BKR7E-11 would be better for this setup. Those
particular copper plugs have a wide tip, unlike the iridium, wich are thinner. Wouldn't the iridium ones be better in preventing detonation than a wide tipped copper plug?"

His responce:

"All of our spark plugs have copper cores. The PZFR6F is a double platinum spark plug. I would suggest dropping one heat range and use the BKR7EIX-11. The fine wire is helps improve ignitability. Also it's important to remember the higher the cylinder pressure the more required voltage is needed to fire the spark plug. This means you will reduce gap with boost increases.

Jon MacQuarrie
Technical Customer Service Representative
jmacquarrie@ngksparkplugs.com"

 

[changedman]

schweet very nice to have people who know what they are talking about!!

 

[Kooldino]

Cool.

 

[t3ase]

His responce: "....This means you will reduce gap with boost increases."

How would we know how much to reduce the gap by?

 

[MSP Pro]

He's merely suggesting that you buy his irridium plug rather than the same plug without the irridium electrode. He's thinking that irridiums will fire over larger A/F ratios, from very lean to very rich. True, but I don't know how resistant to pre-ignition the irridiums are. JoeP pointed out that platinums have a tendency to develop hot spots and pre-ignite, leading to detonation at higher pressures. What about irridiums?

 

[InsidiousMSP]

JoeP pointed out that platinums have a tendency to develop hot spots and pre-ignite, leading to detonation at higher pressures. What about irridiums?

Iridium would be worse for us. Since their melting point is even higher than platinum, they can have very sharp tips. Sharp tips = hot spots = pre-ignition. Iridium plugs are best for high reving NA engines that don't have to worry about pre-ignition.

 

[Mike R]

Hmm, I'd also suggest getting rid of the platinums. Platinums and turbos don't really go together. I've seen plenty of threads on turboford.org about how bad platinum plugs are for turbo'd cars. they have a tendency to burn off the platinum electrode and the car will run like crap. Heck, even on N/A camaro's the guys were having problems with the electrodes coming off in less than 15K miles.

All the turboford guy's run plain old copper electrode autolites.

I agree with JoeP and insidious-stay away from platinum and iridium plugs.

 

[AGR]

still stock.......

....running 10psi. I see no reason to make a change. My car Rocks like a Mutha!!

Exactly; what plugs do our 'SPEED's have?

 

[Emode]

either NGK or Denzo platinum tipped heat level 6
i beleive...........

 

[t3ase]

Again, how do we know how much smaller to gap the plugs? I'm running about 10psi and I'm about to install the new NGK's..

 

[Mike R]

If it's not missing or detonating at the factory gap you can leave it there or try like .05 less than factory.

 

[Ryan]

nice good stuff.

 

[acidbug]

Gapp to 35..mm...that's what i am told..w/ my nitrous..i don't see why you shouldn't w/ high levels of boost!

Chas

 

[t3ase]

.35mm? My gap tool doesn't even go that low. The stock plugs in my MSP were gapped to 0.80 and that's what the gapped the new ones to. .35mm doesn't seem like it'd work too well.