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The lobe separation angle (LSA, also called lobe centreline angle) is the angle between the centreline of the intake lobes and the centreline of the exhaust lobes. [23] A higher LSA reduces overlap, which improves idle quality and intake vacuum, [22] however using a wider LSA to compensate for excessive duration can reduce power and torque ...
The cam can be seen as a device that converts rotational motion to reciprocating (or sometimes oscillating) motion. [clarification needed] [3] A common example is the camshaft of an automobile, which takes the rotary motion of the engine and converts it into the reciprocating motion necessary to operate the intake and exhaust valves of the cylinders.
Camshafts normally have one lobe per valve, with a fixed valve duration and lift. Although many modern engines use camshaft phasing, adjusting the lift and valve duration in a working engine is more difficult. Some manufacturers use systems with more than one cam lobe, but this is still a compromise as only a few profiles can be in operation at ...
The mechanism is a coaxial shaft arrangement where the outer shaft carries the main body of the cam lobe. The main body of the cam lobe is in its maximum duration form. Typically the main lobe body would have a duration of about 450°. The lobe is very long axially, about 45 mm (1.8 in), and its profile consists of conventional opening and ...
cast aluminium alloy; four unequal-length valves per cylinder, 24 valves total, low-friction roller finger cam followers with automatic hydraulic valve clearance compensation, simplex roller chain-driven double overhead camshaft (DOHC – one camshaft for all exhaust valves, and one for all intake valves), continuous timing adjustment variable ...
In four-stroke cycle engines and some two-stroke cycle engines, the valve timing is controlled by the camshaft. It can be varied by modifying the camshaft, or it can be varied during engine operation by variable valve timing. It is also affected by the adjustment of the valve mechanism, and particularly by the tappet clearance.
SOHC design (for a 1973 Triumph Dolomite Sprint) . The oldest configuration of overhead camshaft engine is the single overhead camshaft (SOHC) design. [1] A SOHC engine has one camshaft per bank of cylinders, therefore a straight engine has a total of one camshaft and a V engine or flat engine has a total of two camshafts (one for each cylinder bank).
90° V angle: This design historically derives from chopping two cylinders off a 90° V8 engine, in order to reduce design and construction costs. An early example is the 3.3 L (200 cu in) and 3.8 L (229 cu in) Chevrolet 90° V6 engines , which have an 18° offset crankshaft resulting in an uneven firing interval.