Which spark plugs?

[Spetz]

Hi guys,

What spark plugs would I use for a 6A12 Mitsubishi MIVEC motor that is mildly modified and will be used on the circuit?

ie, colder, hotter than manufacturer recommended? More/less gap?

And what is the overall best brand and type of spark plug?

 

[PolarisX]

I'd probably go stock plug and one step colder depending on what the mods are.

Maybe even the stock plug.

 

[Bgallagher]

Originally Posted By: PolarisX
I'd probably go stock plug and one step colder depending on what the mods are.

Maybe even the stock plug.


If it isn't heavily modified I would stick with the OEM plugs. Just make sure to check them more often if you're doing any racing etc.

 

[fxrider]

NGK - one step colder

 

[TinyVoices]

What mods?

Mods depending, I'd go one step colder.

 

[Vuflanovsky]

Always OEM until you can't get away with it is the motto here...I agree that you'd need to list the mods.

 

[Spetz]

Mods are quite mild:
5mm oversize throttle body
Ported & polished heads
Extractors/exhaust
Tune

At this stage I am inclined to go standard heat range but not sure whether to go copper or iridium?
And what brand is best, or are they all the same?

 

[PolarisX]

Just put the stock plug back in, you will be fine as long as your tune is well done.

 

[Spetz]

And what about iridium or copper?

 

[PolarisX]

I like iridium because they last longer, the car probably came with coppers or platinums from the factory.

 

[Spetz]

Yes they last longer but for a car that is only driven on the track is this something that I should be concerned with?
I mean after all even if the copper plugs last only 1,000 miles that is still years of track time (perhaps the car will never even do 1,000 miles on the track).

Would there be a measurable difference in performance or is it only theoretical between copper and iridium?