Spark Plug Question

[koukidiego]

I have an S14 with an S14 SR that I just swapped. I will be running E85 and pushing slightly higher boost with a GT2860RS, .86. I have a lot of ngk copper spark plugs that I want to use up. Just want to know what is the recommended gap? Also, should I eventually go with a colder plug? This car will only be driven to and from the track. It is not my daily driver by any means, I don't mind swapping the plugs with every oil change. Thanks in advance.

[jr_ss]

You should stick with a 7heat range for your setup. E85 adds a cooling effect, so there is no need for colder plugs. Gapping the plugs is going to be trial and error. I have mine gapped at .026 but I’m also on a much larger turbo and entirely different setup than you. My ignition system probably varies too which is a consideration that needs to be taken into account. I’d start at .030 and see how it runs. Still on stock ignition system? Copper plugs are dirty and foul pretty quickly. Once you burn through them, buy some quality iridium plugs and call it good.

[ultimateirving]

Jr said everything in one post! Stock coils work ok with copper but once you upgrade the coil packs switch to the iridium for sure.

[Kingtal0n]

The larger than gap you can get away with

typically gives better performance and economy

I always start 'big' (.035" to .060" for some coil systems/applications)

And wait for it to tell me gap down (blows out)

Iridium is an incredible long lasting plug when the engine is tuned. I too suggest tuning with coppers then swap to iridium when all setup.

[koukidiego]

Thank you all for all your input. I wish I could devote more time to my car and Zilvia, but work has been insane as of lately. I will be tuning this month. I will let you all know how it goes.