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Radial or sleeve valve vs poppet valve.... Posted by Mike Lynch [Email] (#81) [Profile/Gallery] (more from Mike Lynch) on Sat, 16 Sep 2006 16:16:19 In Reply to: OT: Radial Valve, J, Fri, 15 Sep 2006 19:26:52 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Current engines all use poppet valves, valves with a stem and a flared head the are held closed by a spring and operated by a cam.
Radial valve engines often have a sleve around the piston that exposes open ports. The bore or the sleeve the piston goes up and down in twists to expose ports. I believe there's a way to do it in the head too instead of the cylinder wall. I've seen "drums" in the head that are rotated to open ports. Radial valves can also be called sleeve valves in some applications. Radial engines are another thing entirely and refers to the layout of the cylinders in a circle around a common crank pin and may be sleeve valve, radial valve or poppet valve.
A poppet valve engine always has the port flow blocked by the end of the valve head, the actual flow can't come straight out of the port, the head of the valve is in the way and the flow is around the edges. Radial valves expose a big hole with no blockage. Poppet valves seal well as the force of combustion tightens the seal. Radial valves offer sealing challenges.
Hope the picture works....
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