Piston edges. While the conversation is around radiussing, here’s something slightly different. A dude, who just came in today, over here is running twin KF engines that he sourced out of the UK. These run Dyke rings against the CI bore. Traditionally these just have the square edge on the land above the ring, see pic.
As these engines are not running under any rules, they came modified from the basic 4 deg crown angle. They were flat topped and the edge was chamfered as per pic. While not perfect in terms of carrying the radius to the full diameter, it does look like it would flow better, in that a sharp edge has been removed.
The head, which I haven’t actually seen, does not have any profile to follow the chamfer, but just has a matching 4 deg squish angle out to the bore diameter. This must result in an annular volume at the bore edge. It’s possibly why the piston was replaced, as it was detonated away at the top ring land area above the A/R pin.
.
Bookmarks