99 Baja H2X

502, Procharger, 42LB injectors, Nickerson Charger Cam. Roller rockers and springs and some port work.

Boat was running on this setup for 3 years, AFR around 11.2-11.5.

Last run of the season and this happened! I originally assumed a injector failure, but sent the injectors out to get flowed and they were all within 2% and good to go!

Now im lost, what do you think happened? Every other cylinder was PERFECT, and had no issues.

What cylinder was it ? can you post pictures from farther away to show the cylinders next to it. Just a guess, the gasket was leaking between the cylinders, the one to the right would fire first and burn the fuel out of the one on the left causing it to run extremely lean.

Yes lean. Some type of air leak. intake gasket???????

What HP and how much boost ? do you have any pictures of the head and intake gaskets?

could have been a few diffent issues, but my guess is since your procharged your head gaskets my had started to leak from being under boost maybe the head lifted or head gaskets jus let go enough to let water in the cylinder and the water vaporized and when it does it will erode the piston above the top ring, causing detonation, or your top ring butted together causing the ring land to break and cracking the piston, but as you can see from the pictures, the piston did not only detonate it broke apart causing peices to contact the head and valves also, just my .02

need to see more of the deck,,looks like a head gasket was on its way out.definitely detonation..had the injector driver checked in the ecm,,may be a issue with it on the big end..could also be fuel delivery for that cylinder,the screen at the top of the injector could have been slightly plugged..

I dont have any more pictures as its all off at the machine shop now. It was running around 6-6.5 psi of boost. I will have the ECM checked out as well. Thanks for all the input guys! Just want to prevent future failure.

Look at the bottom right corner of that cylinder on the deck surface, no sealing witness mark and dark all the way to the water jacket. Looks like it was leaking to me.

You had to be close to running out of injector unless you're running high pressure, what fuel pump are you running ?

you may be onto something. look at the top right at also at the left where the valve releif is. it almost looks like the head gasket is for a smaller bore than the block. the witness marks for the sealing ring of the gasket almost disappears in several spots.