Originally Posted by
maxflo777
A rotary disk valve or tube valve will certainly work and best of all with our fuel there's no problem with exhaust valve's cooling and lubrication, but if you want ultimate power you need a cam, only in a cam profile you can obtain really high area under the curve - aka WORK, since it gives a non-linear relation between valve position and crankshaft. With a rotary type valva you can only go to a certain point dictated by the linearity of a 360deg circle - the crankshaft. That's the reason you dont see the F1 guys messing with rotary valves, and maybe thus even 2-stroke engines it would actually rob them a ton of power.
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RC 2 stroke engines do use rotary valves for their intake. That's what the hole in the crankshaft directly under the carburetor is.
The design I am developing has lots of area under the curve, and lots of time with the valve ports fully open. I need to plot the curve and compare it to a typical engine's curve to see the real difference, but I think it's going to be pretty dramatic. It also has no transitional time to get the valve moving and bring it to a stop more gradually like a poppet valve engine has to have. If a poppet valve just slammed open and shut, it (and its valve seat) wouldn't last long.
In other words, the bottom and top of the curve in the disk valve engine has sharp angles, and the "ramp" is a constant angle, and it has a substantial flat top too.
Now I really want to graph it to see what it looks like, given the valve timing I've chosen. I'll post it here so you guys can see what I'm talking about.
The one thing that's going to be hard to compare will be the cross-sectional area of the valve opening. It'll be easy to figure out on the rotary valve, but I'm not sure how to calculate it for a poppet valve.... unless you just calculate the area of the outer surface of the cylinder created by the movement of the outside of the valve face, using the valve face diameter as the cylinder diameter...
I'm not thinking the poppet valve stands a chance once the cross-sectional area is taken into account.
