Flow-optimised valve housing:

- High flow coefficients, low noise emission

Source: http://www.arca.de/index/lang/en/artikel/1103

Flow-optimised shape with axial valve disk

Schuck Group

CYLINDER

The high performance cylinder has flow-optimised ports and an exhaust control valve for top performance.

ENGINE

The high performance 2-stroke engine on the TC 85 is fitted with a power valve to maximise the power band. The high performance cylinder has flow-optimised ports and an exhaust control valve for top performance. Reliable and efficient cooling is guaranteed by integrated crankcase cooling and two radiators.

Husqvarna motorcycles

All valve train components are of low mass. Thus, for example, the M engines feature for the first time low-weight, flow-optimised 5 mm-shaft valves

BMW V10 engine

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Note added at 1 day12 hrs (2014-11-07 00:20:37 GMT)
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"Vizard shows how to optimize flow paths through the heads, past the valves, and into the combustion chamber. "
David Vizard: How to Port and Flow Test Cylinder Heads

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Note added at 1 day12 hrs (2014-11-07 00:28:08 GMT)
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"We made a redesign of the valves springs stiffnesses, divided by 2 at discharge and 4 at suction, and of the port geometry (discharge cylindrical holes replaced by 4 slots, as well as major enhancements in path flows with 3D CFD simulation, as presented in a second article >b>“Part II: Valve plate and cylinder head 3 D thermal & flow
optimization”). These changes provided an optimization of the predicted compression cycle with regard to the condensing pressure (figure 8). The gain was -50% of discharge losses, however the dead volume was increased from 4,4 cc to 5,6 cc."
Source: http://tinyurl.com/l9nqf7l