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“Top end” in the context of engines can indeed refer to two related but distinct concepts:
- Upper range of engine revolutions: This refers to the highest range of engine speeds or revolutions per minute (RPM) that an engine can achieve. It’s often used in discussions about engine performance and power delivery. Pushing an engine into its top end usually means reaching its maximum RPM range, where it delivers peak power before hitting the rev limiter.
- Upper part of the engine: This refers to the components of the engine located above the crankcase. This includes the cylinder head, valves, camshaft(s), intake and exhaust ports, and sometimes the top portion of the cylinder and piston assembly. Working on the top end of the engine often involves tasks like adjusting valve clearances, replacing camshafts, upgrading cylinder heads, or modifying intake and exhaust systems.