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This programmme calculates the specific time-area for a piston controlled inlet port of an engine. From this information the programme calculates the potential power capability of the engine. If you require an increase in power from your engine, you can quickly ascertain what modification will give you the required increase.
For this example we are using the 50cc engine from our exhaust and transfer time area examples. First measure the inlet port opening timing. This example has 1 inlet port with an opening timing of 80 degrees btdc, giving a total duration of 160 degrees. The port has a width of 26mm and a height of 16 mm and corner radii of 5mm, top and bottom.
The potential power output based on the specific inlet time area is 10.83 hp at the crankshaft - labelled 1 in above image. As this value is well short of our required 14.12 hp, the inlet port requires modification. Lets try a new opening timing of 89 degrees btdc giving a total duration of 178 degrees. This in practice requires the lowering of the port by 3.2 mm hence making the port taller by that amount.
The potential power output based on the new inlet time area has now increased to 14.83 hp at the crankshaft - labelled 1 in above image. It is also worth noting that the equivalent diameter of the new port is 24.7 mm - labelled 2 in above image. This dimensions determines the maximum carburettor size requirement and in actual fact it would be pointless using a carburettor larger than this dimension.Top