WorksheetsUnderstanding 4-Stroke Engine Valve Timing
Total questions: 10
Worksheet time: 5mins
During which stroke does the inlet valve of a 4-stroke engine typically open?
Just before the exhaust stroke
Just before the induction (intake) stroke
Just before the compression stroke
Just before the power stroke
At approximately how many degrees before top dead centre (TDC) does the inlet valve usually open in a typical 4-stroke engine?
10°
20°
40°
60°
When does the exhaust valve typically close in a 4-stroke engine?
At top dead centre (TDC)
Just after bottom dead centre (BDC)
Just before bottom dead centre (BDC)
Just after top dead centre (TDC)
What is the usual firing order for a 4-cylinder, 4-stroke in-line engine?
1-2-3-4
1-3-4-2
1-4-3-2
1-2-4-3
Which of the following best describes the purpose of variable valve timing (VVT) in modern engines?
To increase the engine's weight
To improve fuel efficiency and performance by adjusting valve timing
To reduce the number of moving parts
To make the engine run at a constant speed
If the exhaust valve opens too early during the power stroke, what is the likely effect on engine performance?
Increased power output
Reduced power output
No effect
Improved fuel economy
How many degrees of crankshaft rotation are there in one complete cycle of a 4-stroke engine?
180°
360°
540°
720°
What is the main advantage of having valve overlap (when both inlet and exhaust valves are open for a short period)?
Reduces engine noise
Improves cylinder scavenging and efficiency
Increases engine temperature
Decreases fuel consumption only at idle
Which stroke follows immediately after the compression stroke in a 4-stroke engine?
Induction (intake) stroke
Power (expansion) stroke
Exhaust stroke
Valve overlap stroke
In reference to the valve spiral (cam profile), what does a steeper cam lobe typically result in?
Slower valve opening
Faster valve opening
No change in valve movement
Reduced valve lift
