So, I had the LT4 rebuilt last year after it lost compression in one cylinder due to a bad tune from what I thought was a good shop. I spent most of last year dealing with the excessive blowby of the new engine due to the larger than normal ring gaps. So we tried different catch cans but they still filled up too quickly. We ended up installing an engine air oil separator that drains the contaminants back into the oil pan rather than have to drain it. That could mean needing to do more frequent oil changes.
Here's the oil samples going from earliest to latest (right to left in the image). The earliest is UOA is from the engine break-in oil on the dyno. The second sample is from changing the oil after picking it up from the engine builder and driving it home. Finally, the most recent UOA was after a track event (2-3 track hours and the rest are street).
I'm now looking to see why the fuel dilution is higher. It could be due to: (1) short trip driving before oil sample, (2) HPFP gasket is leaking, (3) larger amount blowby of the engine since the ring gaps used were larger than a typical street engine. On recommendation of engine builder, for the next OCI I went to a different oil: Valvoline VR1 20W-50 full synthetic. I will post those UOAs shortly.
Here's the oil samples going from earliest to latest (right to left in the image). The earliest is UOA is from the engine break-in oil on the dyno. The second sample is from changing the oil after picking it up from the engine builder and driving it home. Finally, the most recent UOA was after a track event (2-3 track hours and the rest are street).
I'm now looking to see why the fuel dilution is higher. It could be due to: (1) short trip driving before oil sample, (2) HPFP gasket is leaking, (3) larger amount blowby of the engine since the ring gaps used were larger than a typical street engine. On recommendation of engine builder, for the next OCI I went to a different oil: Valvoline VR1 20W-50 full synthetic. I will post those UOAs shortly.