OP Z

iTrader: (1)

Is there any benefit to using iridium plugs on a stock engine? Thanks.

Sharif@Forged

iTrader: (92)

Yes, they last longer, and require less energy to fire. Iridium claims they last twice as long as platinums. You could probably go 100K miles with Iridums on an NA car. Make sure to get the standard heat range plug, vs. the one step colder that many of the FI people prefer.

TiPIACE

good thread, my bro bought some denso iridiums for his Cooper S and said he noticed an improvement at higher rpm - just the car was smoother

i figured its just a placebo like grounding wires

he went one step colder, any reason why we cant do the same on a bolt-on N.A. engine?

Sharif@Forged

iTrader: (92)

One step colder plugs can be used, but the chances of fouling a plug increase slightly...at least in theory. In practice, a typical NA car running 12.5:1 or 13.0:1 AF ratios is not going to foul out, even the 1 step colder Iridiums. Many track NA 350Z's are higher reving NA VQ35's will still run one step colder.

Z350Lover

iTrader: (2)

So Sharif,

what do you think I should run with my built N/A engine (I haven't got any iradiums yet)... Nismo puts #7, is that stock range or a step colder already?

thanks!

richie

TiPIACE

think thats two steps colder than stock Rich

Z350Lover

iTrader: (2)

Sam,

you serious?! I suppose to use those #7 though...

cheers,

richie

Sharif@Forged

iTrader: (92)

7 is normal heat range. 6 is one step colder than stock.

What is the compression ratio, and intended rev limit of this engine?