Quote:
Originally Posted by Flieger
Boat-tailing is alright but even better is using a GT3 rear main seal. That causes the crankcase pressure to become lower than atmospheric and reduce pumping losses even more. Downside is installation requires splitting the case or so I've heard.
Think of it this way: 2 strokes use the downstroke of the piston to compress the charge for their next power stroke, so the case airflow can be quite significant. In a 4 stroke you compress the air, or at least move it, but don't use it for anything. Just wasted energy.
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I am going back up tonight to help or mostly watch and stay out of the way. The heads are almost done. The new bolts are in for the case and he will be finishing up the heads. I wish I had the time to hang out the entire time but he is building it so fast I just can't be there. He plans to have much of it done this weekend.
I was a little reluctant at first to split the case since all it needed was the heads redone. I am real glad we went all the way. One rod bearing had the start of some problems.
The rod on the right has some slight marring on the bearing surface.
I was stunned to hear him say someone has been in there before. I get to blame the previous owner on something! I bought the car 18 years ago with 80,000 miles. It has 150,000 now. The engine builder found aluminum washers on the case bolts. He said they should be steel from the factory. That was likely the cause of my problems.