more like; got cracks radiating out from the sparkplug holes on the rotor housing faces ...

thought you switched to colder plugs? Or maybe that was someone else, kind of lost track.
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If you’re lubing and torquing only to compress the gasket the wear is fairly inconsequential given the rotor housings won’t last forever. They pretty much go in and out easily by hand except for that final snug to either seat or unseat them. It’s a fairly long fine thread that provides a lot of surface area to bear the load.

 

10k miles of track use? No way. Thats more like 10k miles if idling in traffic, shutting your car off without warning it up and with **** poor fuel mixture and oil meeting.

Also if thats how you maintain a car you put on track you got bigger things to worry about.

 

I did :-), just forgot to post this picture of what OEM plugs looked like. What do you make of it?

The only thing I could think of is that plugs were running very hot and creating deposits once the car is turned off after each track session?

Seems like a lot of deposits on the lead plugs. Funny thing about it car was running just fine.

10k miles (in 5 years) on the plugs and car is only driven to/from and on the track. I premix as well at 0.5 oz per gallon with idemitsu racing premix.

 

it’s normal, and you answered your own question ...

oil in the combustion process doesn’t just disintegrate from existence. Both engine oil from the omp and premix in the fuel are being consumed and as you noted; 10,000 miles worth, a lot of which was high consumption track use (~ 4 - 5 mpg and OMP at max #60 map load)

 

Hmm. I've never had plugs that bad before or after track time. With premix. Those look like city plugs. Sure those aren't also a colder range? Are you always using a particular brand of gas? If so what is it?

Also 4-5 mpg? I was getting 12ish.. depends on the track maybe if it's a tight low mean speed track or autoX 4-5 is more likely.

 

I switched to RE8C-L instead of 7, but otherwise stock plugs seemed fine for occasional track use & autocross. The 8s will foul and the ECU detects misfire after a few hours cruising on the highway on cruise control.

Also, my fuel economy on track is ~6 mpg on a big track (VIR) and I'm tuned fairly lean for a car that still has a cat (0.9 lambda)

 

If you want to read your plugs to get anything like decent info you have to turn the engine off after a full throttle run and then look at them. If you let it idle into the pits and then shut it off it will look fouled and give you crappy information

I ran 10 heat range plugs at track days and had no problems driving home... but they sucked at daily driving and will be fouled in a couple cold starts. For the trouble it is easier to swap back to stock heat range plugs before going home.

Or solve the whole problem and put the car on a trailer 😁

 

I replaced them with 9 and 10 heat range racing plugs for rx8. As for the fuel consumption on the track I got 8mpg at Summit Point Shenandoah this weekend, while summit main is a slightly worse at 7mpg. If I remember correctly I get around 23mpg driving to the track.

Will see if I can get away without swapping these out as this car is not daily and rarely sees city stop and go driving.

I will pull the new plugs after couple track days and see how they look.

swapping lead plugs >> getting trailer to tow the car :-)

 

For the guys that drive to and front the track and also fun road drives like I am. It’s a toy but not always for the track. I may be better off running stock and just changing then once a year which would be under 10k miles. I couldn’t imagine them being or at least doing any damage in that little amount of time.

 

maybe just trying not to insult the slowpokes among us too much

https://www.rx8club.com/rx-8-racing-...merica-259296/

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You would be better running stock trailing plugs in all 4 for the track...

The stock plugs get pretty scorched after about 15 min of WOT running from what I have seen. Especially if you tune the ECU and get rid of the huge oversupply of fuel at WOT 😀

 

I really need to do a tune to lean out WOT maps especially up top, but tuning S2 is major pain from what I hear.

Stock map is not made for track :-(...

 

Versatune has a solution for tuning S2 RX-8. Reach out to them to see what they have to offer. I heard they do remote tuning sessions.

 

I tuned my S2 myself using the basic tuning guides here, but researching the proper race tunes. It's a bit time consuming and if you do dumb overly aggressive stuff you can/will hurt things. The latest off the shelf map from VersaTune is a pretty good compromise that leans it out a lot without being unsafe.

 

Steve from versa tune is gonna be dyno tuning my s2 in a few weeks to gather some more info.
Hopefully he will be able to collect good data. Car is all stock except cat is removed from stock mid pipe for track sessions.
just waiting for him to say the dyno is open.

 

Well got the car out finally this spring and after my first two track sessions last year and thanks to this forum I’ve realized stock plugs may not be all that safe.
So I have been searching for the 7440’s in the 9l and 10 t and was only able to track down one anywhere. So I ended up getting the Denso equivalents.
Now temps next week should be around 40-50 degrees. I know that some guys in the ecoboost world swear by Denso I run ngk.
Any issues with these? I have stock plugs for it and the Denso on the way. Was still gonna try and find some ngk. But these I should get away with the Denso unless you guys see a problem

 

You might want to run the 10's in both... you will know pretty fast if they are too cool.. it will start to foul up at idle

 

I plan on getting. A second pair soon for backup. Would the 9 still be ok for this coming weekend?
Looks like either Are recommended. I assume the 9 is still cooler than the stock plugs. Reason I went with these is I’m in the middle of building g a new house and my trailer is full of stuff to move so I will have to drive the car the 45 min to the track. So I went with the bit warmer ones and will run it a bit higher in the rpm to get to the track.

 

9's should be fine.... thing to do is pull the L plugs after a session and have a look...

 

Good deal. Plan is to get the 10-11 plugs w he n trailer is free and just put them in for track use and stock plugs for street.

 

let me just point out what everyone is missing; colder is better if you want your apex seals to avoid leaping off ski jump mountain at high rpm and the housings not cracking around the plug hole causing another set of issues.

if you’re hammering on it multiple laps then 10.5 is better, just pull them out and clean them, ok? Or at least the L pair.

if you can afford it and the class rules allow it, modifying the rotors and fitting full depth Iannetti ceramic apex seals with that will go a long way to having a longer NA engine performance life.

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Just the guy I was hoping would chime in.
I’ll be ordering some 10’s this week also if I can find available plugs. Or I’ll at least backorder them if possible.
I figured the 9 and 10’s I was able to get would at least be better than the stock plugs. Future plan is to to the 10-11’s for track days and install them the night before then trailer it to the track.
Thanks guys
I feel like I’ve already done to much damage running it with stock ones hard for my first two track days with it. Hoping maybe the colder temps helped me out but doubt it.

 

So I was unable to get the ngk plugs in any reasonable time so I went with the Denso
​​​​​​ I went with the 9 and ten heat range as that’s what was available so not as cold as some but much better than stock.
My stock plugs had 10k on them of track and sported driving and didn’t show a ton of carbon and burn looked good for what little that actually shows.
Half I made the change as with the new falcon 660 tires and ebc brakes I was able to push much harder so I had some way to long in the high rpm moments down the long straight. Didn’t foul any plugs while idling to warm up or cooler down but it was also 38 degrees F that day.

 

9/10 should work great for everything but long WOT runs at high RPM over extended periods of time.
Sprint races should be fine... longer endurance stuff you might start to have issues