Are there any Evo spark plug guru's in here. Please have a look and comment.

Plugs have close to 17K miles on them and some Torco 108 octane race gas this weekend.

The car has run 25psi peak boost, tapering to 19psi at 7600. A/F is 12.5:1 during spoolup richening to 10.9:1 - 11.2:1 at redline for the last 5K miles.

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Spark plugs cannot be read with pictures, but they do look too hot…you need to use a magnifying glass & good lighting.


WOT mixture is indicated by the little gray or black ring of that forms on the ceramic way down in the shell. Richer moves the ring closer to the tip and leaner toward the base.

No ring = plug is too hot or the mixture is too lean or both.

Soot on the metal shell of the plug is mostly an indication of a rich light load mixture.

Looking at the color of the plug’s ground strap & the location of the blue line can be an indication of ignition timing. Ideally, you want this blue line to be just below where the ground strap makes the bend. More timing puts the mark closer to the base and less timing moves it towards the tip due to increased or decreased heat in the chamber (some people will argue this as a heat range indicator).

Detonation shows up on the plugs as spotting on the porcelain. If you see black spots on the porcelain then you may need a colder plug. If you see little shiny spots then your detonation is severe enough to deteriorate aluminum in the combustion chamber.

Blistering of the insulator indicates a plug that is too hot or overly advanced timing.

Of course this is just one persons opinion & others may disagree….reading plugs will always spark debate.

Hope this helps

 

I'm blind as a bat, so that's why I took the pictures in macro, I figured it might be a good way of looking at them.

Yea, these plugs are telling me mixed things. From what I could tell, possible excessive timing and/or needs 1 step colder plug.

Thanks, I've read some on reading plugs, my last set came out black and fouled. This tune is a bit leaner (but not lean my any means 11.1:1 AFR). I'm thinking this is just a result of 25psi on stock heat range plugs.

 

Try a set of colder plugs...maybe copper until you get it figured out, then switch back to iridium. If they foul with a good afr & timing then they may be too cold.

The best way I have found to get a good read on the plugs is to make a pull,1/4 mile or 3rd gear, then shut the vehicle off immediately after, coast down, stop & pull the plugs for inspection. That is the process I use while tuning & it has not failed me yet , Of course this is most safely done at the strip

good luck

 

(1) You must use new plugs to get a good reading on them.
(2) Make a pass down the strip or a private road and limit your idle time. It can be hard with turbo cars because they need to be cooled down. If you have access to a track that's even better run a few laps pull in the pits and pull the plugs.
(3) Plugs can't be read accurately on the Internet do to monitor color.

Your plug look just like you have described them 17k on them with various fuels on them. If your going to use high octane and more boost get some of the colder copper plugs for the track days there cheap and easy to read. Switch back to your DD plugs when your done at the track.

Link for plug reading 101 http://www.dragstuff.com/techarticle...ark-plugs.html

 

subs

 

Yea, I think the problem is 1 step colder long reach plugs for the IX are all crazy expensive.

 

IKH24 are one step colder and IKH22 are Denso Iridium plugs for the 9 with same reach as stock NGK's Yes NGK does nto make one step colder unless you go to some racing plug. thsi is all second hand info. so do a search to see more info.

Optionsauto.com sells the Densos for around $11 a piece I believe

 

thanks for the tip, I was recently reading about running some long reach subi plugs that come in steps colder as well.