The table below shows the calculated squish velocities for a 125cc engine at 0, +5 and -5 degrees squish angle. This is important, as nearly all squish bands in practice have a slight divergent angle, though there have been some with convergent angles. Our programme however can handle squish angles other than zero which the QUB programme uses as default. It is apparent from the next image that The Torqsoft Squish Velocity Programme gives the exact same output for maximum squish velocity (MSV) and the crank angle at which this occurs. Shown immediately below is a scanned page from the book titled "The basic Design of Two-Stroke Engines" by Professor Gordon Blair - Queens University of Belfast. The value that is of most interest to the engine tuner is the peak squish velocity. The answers are calculated as 26.01 m/s peak squish velocity at a crank angle of 9 deg btdc and the total squish kinetic energy is 3.0mJ. Enter the rest of the data and hit the calculate button. Within the engine box enter 54 for the Bore, hit the tab key and enter 54.5 for the Stroke, hit the tab key and enter 110 for the Rod Length. The combustion chamber is centrally located and has a squish area of 40% and a squish clearance of 0.85 mm. The exhaust port opens at 83 deg atdc and the peak power speed is 12000 revs/min. Suppose you have a two-stroke engine with a 54.0 mm bore, a 54.5 mm stroke and a rod length of 110 mm. This means that it is easy to check the "tune" of an engine and make decisions on if there is scope for further modification of the engine. The Squish Velocity Programme enables the user to calculate the peak squish velocity, the crank angle location of the peak squish velocity and the total energy of the squish action for one compression cycle for a two-stroke engine.
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