Large rpm drop

nm9stheham said
That's interesting info, YR.... Curious: Is that from measuring the actual eyebrows or some total volume and assuming the difference is in the eyebrows? I measured some eyebrows but not on a KB or Icon. And I always add in 1 cc anyway for the volume down by the top of the piston. If Charles piston eyebrows are 2 cc larger (than the 5 cc published number), then he should be right around 10.5 for SCR... so still pretty good.

(FWIW... I assumed 110LSA and 106 ICL in my DCR number.... just because they are pretty common factory grind numbers.)

It's easier to figure out something is wrong when using a flat top piston.

When you do the down fill you can easily calculate the valve notch volume doing that, and almost all the time they are bigger than advertised.

It a bit more difficult with a domed piston. But you can do it. It's also quite funny that dome volumes are usually not what the piston manufacturers claim. They are usually LESS that advertised.

That's why I don't like taking the word of the guy making the Pistons. They are wrong often.