spark plug melting at high horsepower

DLV8

DLV8

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Little history, a good buddy of mine bought a lightning a few years back, after sending a rod out the block he build himself a new engine, ever since then he's has melted 2 spark plug within 200Km of having it tuned, always on the same cylinder.

Looking at the image what do you think is causing this? A/F ratio seam to be around 12:1 @ ful throttle so it's not running lean. the only thing I can think of is detonation? Anybody else ever seen this?
 

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Injector, or coil pack. Swap trek around to see if it changes...
Also switch to an autolite race plug..
Its ground strap is cut back so it doesn't cover the electrode and retain heart.
And what gap is he running?
 
this should be better.
 

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Stock ignition or what? My brothers boat did this but even worse. Turned out to be the msd ignition module shorted out inside.
 
24vriviera said:
Injector, or coil pack. Swap trek around to see if it changes...
Also switch to an autolite race plug..
Its ground strap is cut back so it doesn't cover the electrode and retain heart.
And what gap is he running?
Click to expand...

Coils where swap around the first time he melted one. He's using NGK iradium trx7ix which are, in my opinion, a good plug. IIRC they are gaped at .035''.
 
Move the injector to another hole. Is it boosted?
Try a trx8ix
Its a cooler plug
 
RyanH said:
Stock ignition or what? My brothers boat did this but even worse. Turned out to be the msd ignition module shorted out inside.
Click to expand...

Yes, coil-on-plug.

95cummins5.9 said:
Too much timing on that hole?
Click to expand...

Don't know how that would be possible.

crackerman said:
Move the injector to another hole. Is it boosted?
Try a trx8ix
Its a cooler plug
Click to expand...

That's what we did, we also put the coil on a different cylinder, originally it had trx6ix so we are already a step cooler.

We ended up pulling 2 degrees of timing off last night, we're going to try that and see.
 
you still didnt answer if it was boosted or not. but as you have coil on plug i will assume that it is a blown lightning?

12.0 may be a little lean still, i always liked solid 11.50 afr when tuning my turbo mitsu. safe on pump gas any day of the week.

also, those iridiums retain heat in the very tip, and can turn into glow plugs. same with platinum tipped plugs.
you may try a non iridium, NON projected tip, restistor plug. (for instance, i ran ngk br8es on my mitsu)

it may need plugs changed more often, but will not cause heat issues like an iridium will.
 
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The lack of deposits on the melted plug tells me that that particular cylinder is running lean.
 
That is some serious detonation.. And 12:1 is a safe A/F, granted it is getting a correct reading.. Does he have an EGT gauge? If not, he may want to get one and keep an eye on it. Having an A/F and EGT gauge are worth there weight in gold when tuning. It seems like there is definitely a problem in the ignition system or a problem in the tune (granted you are running the proper fuel for the tune).. FWIW, after running a very picky boosted car for over 4 years (changing fuels, tunes, boost levels, timing maps, etc.) and burning through some plugs, I went to copper core and one heat range colder (NGKs) and have never looked back. Haven't had any issues since the switch. Copper cores don't last as long though, that being the trade-off.
 
crackerman said:
you still didnt answer if it was boosted or not. but as you have coil on plug i will assume that it is a blown lightning?

12.0 may be a little lean still, i always liked solid 11.50 afr when tuning my turbo mitsu. safe on pump gas any day of the week.

also, those iridiums retain heat in the very tip, and can turn into glow plugs. same with platinum tipped plugs.
you may try a non iridium, NON projected tip, restistor plug. (for instance, i ran ngk br8es on my mitsu)

it may need plugs changed more often, but will not cause heat issues like an iridium will.
Click to expand...

yes, sorry, it's a blown lightning. I guess ill try a br8es, I just always though those where a 2 stroke spark plug.

mhuggler said:
The lack of deposits on the melted plug tells me that that particular cylinder is running lean.
Click to expand...

We swap injector with a different cylinder, will see if that's the problem.

4bt40 said:
That is some serious detonation.. And 12:1 is a safe A/F, granted it is getting a correct reading.. Does he have an EGT gauge? If not, he may want to get one and keep an eye on it. Having an A/F and EGT gauge are worth there weight in gold when tuning. It seems like there is definitely a problem in the ignition system or a problem in the tune (granted you are running the proper fuel for the tune).. FWIW, after running a very picky boosted car for over 4 years (changing fuels, tunes, boost levels, timing maps, etc.) and burning through some plugs, I went to copper core and one heat range colder (NGKs) and have never looked back. Haven't had any issues since the switch. Copper cores don't last as long though, that being the trade-off.
Click to expand...

The truck was dyno tuned with supposodely a conservative tune. the only other thing I could thing of would be the IAT being blistering hot, since he's still running the factory eaton blower @ 16psi thus causing the detonation.
 
Maybe check the indexing of that plug, was it the same on both of the burnt plugs? Also do you check A/F ratio at the tailpipe or individual cylinder... maybe that cylinder is getting more air for some flow distribution reason that is causing it to run lean...
 
truly the only way to tune is on a engine dyno and to read each cylinders egts and a/f for each cylinder. being a lightning, does it have the factory charger on it or has he went to something like a whipple instead? those plugs look terrible as far as tuning goes. even the ones with the ground strap still intact look like crap.
 
Still has a factory water to air intercooler. Needs a better heat exchanger, bigger pump or both, also seperate the water cooler from engine coolant. It will need its own reservoir now too, but worth the cooler air.
 
well took the plugs out tonight only to find one other melted on a another cylinder. took a snap on camera inside the cylinders and looks like we have two piston that have cracks. so seams a tear down will be in effect.

Now being in his shoes, what would you do, specificly, as far as the 700$ dyno tune which proves to be worthless?
 
I'd seriously step away from an iridium plug like others has already said. I'd say cracked piston was due to the detention obviously.
 
your problem is the injector and running the wrong plug for the situation, get those plugs swapped for some copper plugs like others have mentioned and send those injectors out to get flow tested and cleaned.
 
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