That's pretty sweet that some of the YS engines supercharge that way. I have to admit, I just assumed they were using an external supercharger.

I had also wondered about the extra turbulance that a slotted port design would introduce. It does greatly simplify (and compact) the valve assembly, allows the glow plug to be centered, while allowing a non-linear opening and closing. I wonder if these advantages would matter...

I can totally see how flow would be impeded by small slots vs one large open hole. ...especially with liquid flow, as surface tension would probably really kill it - BUT, we're not working with liquid. There's got to be a way to make a rig to test gas flow through a few different arrangements of slots, holes, etc... I'm sure one already exists for physics type experiments.

I should really do some experimentation with that sort of rig before deciding how I want to do the valve. It shouldn't be that hard since all I want to test is relative flow rates - I don't need hard numbers, just "is this one better than that one" tests.