Trying to understand how serious this is and if carbon buildup could be the cause. Car only gets driven 200 miles/year and some years never gets driven at all. When it does, it's either going to local cruise nights or being punished severely at the track. Piston tops have always been heavily carboned up from the recent owner and I switched to E85 early this year and have noticed tops already getting cleaner after only 1 tank of gas and 1 trip to the track. I scoped the motor after 6 passes, plugs were running good (TR7IX) but noticed what seemed to be detonation marks. Although these marks look like similar craters that wiped out the dinosaurs, they are small, and less that the diameter of a pin, more like the shaft diameter of a pin, and around .005" deep. Obviously, it's some form of detonation but wondering if it was triggered by carbon buildup or just getting pushed too hard.



After seeing these, I gave the cylinders a good 3 day soak which cleared up a lot of the carbon.



These are stock LS3 Hyperutectic pistons and I won't babble on about the build or tune unless someone is interested. Just want to know what others think as to the cause and how serious it is, in your opinion


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I was told that hot oil gets through the valve seals then dripps from the seals to the top of the pistons. It begins to cake up. I changed my valve seals over to fel pro. There supposed to be a lil bigger and cover a bigger space of the valve stem.

 

Don't think it's oil since the motor has less than 4000 miles on it. After the soak, most of the marks I thought were detonation were actually blown off chunks of the carbon, a little smaller than a grain of salt and the piston tops look good.

I'll just keep an eye on it but it seems like nothing to worry about