I would say injector failure/cylinder not getting fuel. One piston melting to death and everything else is fine? Very strange...

But you had them tested to be good? Maybe a loose connector under load?

 

Not getting fuel means not having a combustion event means nothing breaks, it just misfires.
Getting partial fuel is when Hiroshima happens.

 

“Everything else is fine” is yet to be determined. The other pistons and bores need to be examined. When the residual gas layer is compromised there are obvious signs of damage, when it’s not the signs are more subtle. That is a common or known weak spot on the Malhe/ST pistons. I reshaped that area on the 9.5 ST pistons in my engine. FWIW I would not use 9.5:1 for more then 14-15psi on gas.

 

You are right, I should have said "not ENOUGH fuel", therefore my guess with the connector or maybe a slightly damaged wiring loom from pulling the engine.
That damage happened in 100 miles or so, something is wrong.
No question the tune is aggressive, but I think there is more to it

 

That piston has seen some ****.

Sorry you're having to deal with this man, and it's that much harder when you can't get clear answers. All I can really say at this point is to take things slow when tuning after rebuild, and definitely get a new tuner.

It does seem very quick for that type of damage, and also odd that the other pistons seem fine. Are you going to pull down the rest of the bottom end?

Got your piston order and I saw some wisecos on the shipping desk this morning so I think they're going out today.

 

Do you decrease the gap or use pre gapped 1.1mm ?

 

NGK also offers these in a BKR7EIX which has a gap of .032". For FI applications I recommend .025" -.035".

 

Here is a list of NGK plugs for our application. I have run all of them. I can't say that any one plug is better then the rest. Even the nickel plugs run good. I have also never worn out a set. I'm currently running the Ruthenium plugs which have about 500mi on them, so no opinion yet.

NGK 6364 BKR6ES Nickel Reg Gap
NGK 5553 BKR6ES-11 Nickel 1.1mm Gap
NGK 4952 BKR7ES-11 Nickel 1.1mm Gap
NGK 6418 BKR6EIX Iridium Reg Gap
NGK 3764 BKR6EIX-11 Iridium 1.1mm Gap
NGK 2667 BKR7EIX Iridium Reg Gap
NGK 6988 BKR7EIX-11 Iridium 1.1mm Gap
NGK 92400 FR7BHX-S Ruthenium Reg Gap, Turbo specific plug

 

Depends on coils. Bigger gap is always better. Bigger kernel gives the flame front a bit of a head start. Stock coils usually require reduced gap. Big dog coils can run big gaps event at 25psi
https://supermiata.com/maxspark-pnp-...n-upgrade.aspx

Basically start with OEM gap and drive it. If you get misfire under boost, either reduce gap or improve coils until you don't.