The upper section of an internal combustion engine, consisting of the cylinder heads, valves, camshafts, and intake manifold. In performance tuning, the term also refers to the engine's power delivery at high RPMs or the vehicle's maximum achievable speed. A rebuild of this section fixes valve seal leaks and restores compression without removing the engine block from the vehicle.
We're doing a top-end rebuild this weekend to fix those leaky valve stem seals.
Do not mix it up with
- Bottom-end: The bottom-end refers to the block, crank, and pistons, while the top-end covers the head and valvetrain.
Related terms
Bottom-end
The lower section of an engine block containing the crankshaft, connecting rods, and main bearings.
Cylinder head
This cast metal component bolts to the top of the engine block to seal the combustion chambers.
Intake manifold
The engine component that distributes incoming air or air-fuel mixture evenly to each cylinder.
Short block
A partially assembled engine bottom end lacking the cylinder head and oil pan.