Spark plugs - resistor or non resistor type

[martinlaw]

What are the advantages or disadvantages of plugs with or without resistors.

Reason i ask is i have one set of plugs for road use (resistor type)and one set for track use (non resistor type - I also assume cooler!)

Cheers,
Martin.

[CanAm Dave]

Hi Martin

It all depends if you are using an ECU and on-board electronics. The resistors are there to reduce electromagnetic interference. Without them some engines may experience misfires.

Regards Dave

[martinlaw]

Thanks Dave,

I assume then it will not affect my car either way with not having a ecu, only the MSD ignition?

Martin.

[GTWayne]

Martin, I have been recommended by my engine builder to run hotter plugs for track work. I use NGK BP6ES for the road and have 7's for track work, if I ever get out on track that is!

[bluesatin]

I have been running Denso Iridium plugs for a couple of years and they work a treat. The very small tip (0.4mm) helps stop the plug sooting at idle.

[eliot]

GTWayne said:

Martin, I have been recommended by my engine builder to run hotter plugs for track work. I use NGK BP6ES for the road and have 7's for track work, if I ever get out on track that is!

7 is a colder plug than a 6, which means soaks away heat more.
Essentially the plug needs to run at certain temperature so it "self cleans" - the lower the number the hotter [it operates at]. For high compression/boosted engines you want a colder plug, but not so cold that it fouls (doesn't get hot enough to self clean).
I think/hope that makes sense!
ETA:
http://www.ngksparkplugs.com/techinfo/spark_plugs/...
Explains it better than me...

Edited by eliot on Monday 14th April 19:58

[martinlaw]

Thanks for the advise everyone.

I will use a set of cooler plugs for the track day.

Cheers,
Martin.