🔍 Key Concepts

• Differences in scavenging and valve arrangements between two-stroke and four-stroke diesel engines • How poppet valves and camshafts are used in a four-stroke versus how ports are used in many two-strokes • Geometric difference between a 60° V and 90° V cylinder-bank angle when viewed from the front

💭 Think About

• Look closely at the cylinder heads: do you see valves operated by rocker arms and a camshaft, or does the piston uncover ports in the cylinder wall? What does that suggest about the operating cycle? • Visualize a right angle (an "L" shape, 90°). Does the angle between the two cylinder banks look closer to that, or much sharper, closer to an equilateral triangle corner (about 60°)? • Ask yourself which options can be eliminated first: once you decide on the operating cycle, how many choices are left, and then which V-angle best matches the drawing?

✅ Before You Answer

• Verify whether there are intake and exhaust valves in the head, each worked by a camshaft and rocker arms – strong sign of a four-stroke arrangement. • Check if there are no large scavenge ports being uncovered by the piston at the bottom of its stroke – that would typically indicate it is not a classic uniflow/loop-scavenged two-stroke. • Estimate the included angle between the two banks by mentally sketching a right angle (90°) across the drawing and compare it to a narrower 60° angle before choosing between the remaining options.