GPM

What's your HP goal ?

Mtuned

Boat was at about 5400 RPMS on a 4 Blade 30P. I will be flashing it to rev to 6k, and looking for enough power to get me to 5800-5900 rpms

Tinkerer

That doesn't look like detonation to me - That piston melted badly. Are You running headers? Did the header lose water for that cylinder? If it did that cylinder would have run lean.

Full Force

iTrader: (5)

um yes that IS detonation from being LEAN

Tinkerer

If detonation did all of that damage I would expect to see bearing damage from being hammered to death. Yes I know that detonation is caused by a lean condition. But usually detonation bad enough to cause that much melting would crack the piston. For some reason that cylinder went lean. I would think if the head gasket went bad or the head lifted you would have a burn mark on the head or the block. That damage didn't happen in ten seconds. ten seconds running lean melts eyebrows - ask me how I know.

MILD THUNDER

iTrader: (3)

Yes. Seen pistons that got lean and burnt up in one pass, torches a hole in it. Rest of piston top looked nice minus the hole.

FIXX

iTrader: (2)

it peeled the ring land,,seen it on many nos engines and has done it in less than 7 seconds....its detonation..

FIXX

iTrader: (2)

which procharger did you have?? they have a max rpm limit and when you over drive them they self distruct..check the chart on prochargers website to see what you can spin it to,also if you up the pounds of boost you will need a bigger cooler which you can get from frozenboost.com

Full Force

iTrader: (5)

Bearings don't always get damaged like that, besides I don't see a pic of the bearing to see that anyway, that is detonation period, ask me how I know.....lol and yes a 10 second WOT pass can and WILL do that.....

mike tkach

iTrader: (3)

that is detonation,it appears the octane might have been to low,maybe got some bad fuel.we must keep in mind that the afr reading is an average of the cylinders on that bank and on all big block chevrolet,s some cylinders will be leaner than others.it seems strange that you ran this combination for 3 years without problems before the failure.if you did not make any changes i would suspect either a bad injector or a driver problem in the ecm.the failure was not caused by a head gasget problem.generally a failure like this one is caused from to much ignition timing or a fuel with to low of an octane rating.as far as the bearing being hammered,if you measure the upper half of the rod bearing from this cylinder i guarentee you it is hammered.