Reading Spark Plugs

[!Zar!]

My car was experiencing spark blowout, and I finally found out why.
These plugs were brand new with less than 200 miles of street driving.
I took the car out to the race track, and half way or so through my day I noticed spark blowout during full throttle nearing max boost.
I finally pulled the plugs and found this...

NGK bkr7e gapped at .028

Track temps were high. 102+f ambient temperture.

Plugs for cyl 1 and 4 seem to be the only ones that look abnormal and have the destroyed ground strap. I would have though detonation was to blame, but the dark black on the fire ring would lead one to believe the car is running rich. I will need to slap it on the dyno and see what's up. But for now I'm down to hear what you all have to say.
http://i31.photobucket.com/albums/c391/TurboDrifterZar/photo2-33.jpg?t=1349544782
http://i31.photobucket.com/albums/c391/TurboDrifterZar/photo1-36.jpg
http://i31.photobucket.com/albums/c391/TurboDrifterZar/photo3-27.jpg?t=1349544788

[godsmack]

Detonation and then rich from the lack of sufficient spark due to them being gapped at like 2mm.

[The Dude]

Try a heat range colder. How much boost are you running?

[!Zar!]

Detonation and then rich from the lack of sufficient spark due to them being gapped at like 2mm.

The plugs I just put in are at .029. Should I gap them at .034 maybe? I am running the Circuit Sport DIS (http://www.phase2motortrend.com/cisppnpigamp.html) so I guess I can safely run a bigger spark. My timing is at +20*. Maybe I'll back it back off down to +15*.

Try a heat range colder. How much boost are you running?

I was thinking about running a colder plug.

I'm at 17psi / 1.17bar

I know that gt2871r guys have a setup similar to mine and run the same plugs I currently run, with the same gap / power that I am pushing.

I was thinking maybe just the combination between the high ambient temps and not running race gas is what did it.

[shagspeed]

The plugs I just put in are at .029. Should I gap them at .034 maybe? I am running the Circuit Sport DIS (http://www.phase2motortrend.com/cisppnpigamp.html) so I guess I can safely run a bigger spark. My timing is at +20*. Maybe I'll back it back off down to +15*.



I was thinking about running a colder plug.

I'm at 17psi / 1.17bar

I know that gt2871r guys have a setup similar to mine and run the same plugs I currently run, with the same gap / power that I am pushing.

I was thinking maybe just the combination between the high ambient temps and not running race gas is what did it.

17PSI on a 2871 hard on the track.. It was detonating I'm sure.. Though the mixture looks okay you just over ran the fuel IMO ... I would ping on a stock T28 on my GTI-R motor @ 17PSI .. a 54C head flows better too so the 52F head is more likely to ping .... Well that's my opinion .. If you can look into the Cyl look for little pits in the piston's ..

[godsmack]

I was saying that you ended up being rich as a result of the tips melting and then having a 2mm gap. lol. I would definetely pull some timing out if you're not running higher octane. At 15*btdc you should run 91octane. At 20* I would run no lower than 93 and still would be weary about knock.

[K3MPS]

Looks like pre-ignition to me... improper timing, too hot a spark plug, low octane fuel, too lean an air/fuel mixture, or engine overheating.

[fliprayzin240sx]

Wow, never had issues with my plugs when I was running my 2871. How's the tune on it and what size injectors are your running?

[slider2828]

^^ Copied from a website huh......

Pre-ignition, basically there is combustion before the spark.... timing, fuel octane, possibly overheat......

[!Zar!]

I think it is due to really high track temperatures, +20° timing, and running premium gas (91oct). Not to mention Thunder hill is a pretty fast track.

Next time I will run race fuel at the track and if it is really hot I will pull some of the timing out.

[shagspeed]

I think it is due to really high track temperatures, +20° timing, and running premium gas (91oct). Not to mention Thunder hill is a pretty fast track.

Next time I will run race fuel at the track and if it is really hot I will pull some of the timing out.

Yah.. +5 deg timing is massive... With that kind of damage on the plugs I bet your pistons are compromised . I bet there will be no next time.. It can only take so much... BTW is your bottom end forged?

Here's my 91mm sleeved SR I just pulled down... It wil almost always show signs of detonation on the intake side or trust side where most heat is.. So see if you can get a scope in there and look around ..

https://sphotos-a.xx.fbcdn.net/hphotos-snc6/177618_4146138930422_764439330_o.jpg

[godsmack]

And just to make sure I'd def put a scope in those cylinder just to make sure that those tips didn't fall off and cause damage to the walls and pistons.

[!Zar!]

I'll get a scope down there once I get my hands on one.

I'm running +20° timing because Enthalpy suggested I run that. Sadly 91 is the best available in California when it comes to premium. Maybe I'll keep smaller cooler tracks for pump gas, and on days where it is warmer out, I'll run race gas.

Seems to be common as seen here: http://zilvia.net/f/tech-talk/450519-enthalpy-ecu-20-degree-timing.html

[shagspeed]

I'll get a scope down there once I get my hands on one.

I'm running +20° timing because Enthalpy suggested I run that. Sadly 91 is the best available in California when it comes to premium. Maybe I'll keep smaller cooler tracks for pump gas, and on days where it is warmer out, I'll run race gas.

Seems to be common as seen here: http://zilvia.net/f/tech-talk/450519-enthalpy-ecu-20-degree-timing.html

Okay if it was tuned for 20deg base then fine.. Back in 1999 Clark@JWT tuned mine for 20deg .. Its the only way we could get it to idle with 4bar@72lb/hr injectors .. I just hope he pulled timing on your like Clark did on mine.. Because if not I know on the top end under boost an engine can form safe to blow up in 2deg of advance ... This is why I write my own tune's or trust Clark.. You never know this days .. Best of luck and Happy Motoring ..

[slider2828]

Yea Thill is hot... but THill sells 103 unleaded at the pump there.... Just do 50/50 mix would have been a good idea.... I know THill well, but just for track...

[!Zar!]

Yea Thill is hot... but THill sells 103 unleaded at the pump there.... Just do 50/50 mix would have been a good idea.... I know THill well, but just for track...
True. This was my first time running my current engine setup on track, and normally pump gas works fine. Next time I will mix 103 for sure.

I actually tracked my car that day with NCRC.

I would run no lower than 93 and still would be weary about knock.http://www.iiez.info/song9-1.jpghttp://www.iiez.info/samz3.jpghttp://www.iiez.info/song9-5.jpghttp://www.iiez.info/song9-4.jpghttp://www.iiez.info/song9-2.jpghttp://www.iiez.info/song9-3.jpg

93 isn't sold at the pump in California.