which piston would you run?
04-06-2011, 09:24 AM
#24
04-06-2011, 10:10 AM
#25
Where's the skirt coating? How about the positive displacement on the other side of the valve reliefs to make the quench more effective, as well as making a deeper relief without giving up alot of compression? How thick is that top ringland?
The pictures are of -18cc blower pistons. They are negative displacement flat tops, if you will. For more positive displacement on the flat side of the head the dish would be smaller but deeper. This creates a ramp for the flame front on the piston side. Sure, you lose some squish with the flat dish but it provides smoother flame travel, more even cylinder pressure and resistance to detonation.
I didn't measure the top land. It looked plenty thick vertically and there is a surprising amount of material horizontally for a dished piston design of that bore size. This allows good heat transfer and gives added strength to counter bending force around the circumference of the land. The exception is at the valve reliefs, which I see as a potential weak spot. We shall see.
Last edited by swift700; 04-06-2011 at 10:43 AM.
04-08-2011, 08:36 AM
#27
Looks like a nice set of pistons. 2618Alloy? What clearence are they calling for?
The finish quality is excellent on CP's. Here's a piston of similar design built by a large manufacturer. The valve relief is cut almost to the bottom of the top land. That's a big weak spot. Notice that burr? Poor quality control:
Last edited by swift700; 04-08-2011 at 08:41 AM.
