If it's done a piston or ring that quickly of say it wasn't/hasn't been mapped properly. What set up/engine management are you running? Any fuelling mods?
bad build or bad map, 80% duty is high for 0.5 bar
did u get it mapped before u ran it in, am confused here.Sorry miss wrote, they were 80% after mapping after ran in at 1.6 bar
Does not really matter if it was "run in"
One injector could be slightly bad How does the spark plug electrode look on cylinder 4?
And 1.6bar with a unichip is not the best idea.
Fuel used on 1.6 bar?
Plugs look perfect, what's wrong with 1.6 bar on unichip? Running 99ron
She was mapped by a very reputable tuner who is very professional he talked me through everything as he was doing it ect engine was built by local engine builder but when I got engine back I thought there was a lot of crank pressure going into catch tank but thought it must be ok as just been re- built
At that power levels you want a good management to hold the engine together
Can you see any detonation on nr 4 plug?
How bad is nr 4? Maybe it needs some more seating
Is the engine builder reputable? Was the rebuild done with a rebore and pistons to match?
Any idea if the piston to wall clearances were logged?