The absolute speed limit is approximately 6700 rpm. After this speed, the valve springs begin to compress and decompress so quickly that they no longer ensure perfect opening and closing of the valves. Valve springs can break, resulting in consequences such as a collision between the valve and the piston.
To prevent this from going too far, Audi engines have a built-in speed limiter, which, when approaching the above speed range, stops the further increase in speed by cutting off the supply of fuel.
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