🔍 Key Concepts

• Relationship between crankshaft speed and camshaft speed in a four-stroke/cycle engine • How many crankshaft revolutions occur for every complete engine cycle in a four-stroke engine • What the camshaft must do in relation to opening and closing valves once per cycle

💭 Think About

• In a four-stroke engine, how many strokes happen in one full operating cycle, and how many crankshaft revolutions does that take? • For the valves to open and close at the right times, should the camshaft rotate faster, slower, or at the same speed as the crankshaft in a four-stroke engine? • Once you know the speed ratio between the crankshaft and camshaft, how do you apply that ratio to an engine speed of 1550 RPM?

✅ Before You Answer

• Be clear on the stroke sequence: intake, compression, power, exhaust, and how many crankshaft turns that requires • Confirm whether the camshaft turns once per cycle or once per revolution of the crankshaft in a four-stroke engine • After deciding the speed ratio, multiply or divide 1550 RPM accordingly and check which choice is closest to that value