Engine Mechanics Quiz

The first step in a four-stroke engine cycle where the piston moves downwards, drawing in a mixture of air and fuel through the open intake valve.

The second step where the piston moves upwards, compressing the fuel-air mixture, increasing pressure and temperature.

The third step where the compressed fuel-air mixture ignites, creating a powerful explosion that pushes the piston down.

The final step where the piston moves upwards, forcing the exhaust gases out through the open exhaust valve.

The timing of the intake and exhaust valve opening and closing, ensuring that the mixture is drawn into the cylinder at the right time.

A mechanism within the engine that controls the opening and closing of the valves, enabling each stroke to happen at the right time.

The amount of time the spark is advanced before the piston reaches top dead center (TDC) to ensure efficient and complete combustion.

The pressure exerted on the piston by the expanding gases during the power stroke, pushing the piston down and generating power.

A raised part on the camshaft that, as it rotates, lifts the valve lifter (tappet) to open the valve.

A component that transmits the camshaft's motion to open and close engine valves; often called a valve lifter or tappet.

A device that transfers motion from the cam follower to the valve, often found in engines where the camshaft is located away from the valves.

A lever that converts the up/down motion of the push rod into a rocking motion to open and close the valve.

A spring used to close the valve after the camshaft lobe has passed the cam follower, allowing the valve to return to its closed position.

A circular shape divided into 360 degrees (360°), used to represent a full rotation of the crankshaft.

The angle of rotation of the crankshaft when a specific event in the engine cycle occurs, often measured in degrees.

The complete working cycle in a piston engine involves four strokes: intake, compression, power, and exhaust.

The pressure changes during each stroke of the four-stroke cycle can be measured by a device called a piezo-electric indicator.

The indicator diagram shows the pressure variations inside the cylinder throughout the four-stroke cycle. It helps identify if there are any issues with the engine's settings.

The intake and exhaust valves are opened by the camshaft and closed by springs.

To efficiently get exhaust gases out and fresh air in during the short time available, the valves are kept open for a longer duration, given by the crankshaft rotation.

Any deviation from the normal pressure pattern on the indicator diagram suggests problems with engine settings like mixture, ignition, or compression.

Incorrect engine settings, like mixture proportions, ignition timing, or compression, can lead to deviations in the pressure pattern on the indicator diagram.

The position of the piston when it's farthest from the crankshaft, at the end of the upstroke.

The position of the piston when it's farthest from the cylinder head, at the end of the downstroke.

The period where the piston moves very little despite a few crankshaft degrees, resulting in minimal work done.

One complete rotation of the crankshaft, equivalent to 360 degrees.

A type of piston engine with cylinders arranged radially around a central crankshaft.

An engine layout where cylinders are arranged in a single line along the crankshaft.

An in-line engine where the cylinders are positioned below the crankshaft.

The ratio of an engine's weight to its power output, a measure of engine efficiency.

The area of an engine facing the oncoming air, influencing drag.

A method of keeping the engine cool using air circulating around the cylinders.

A method of cooling the engine using liquid circulating through the cylinders.

A type of engine with an even number of cylinders arranged in two banks, forming a 'V' shape.

The exhaust valve stays open slightly after the piston reaches Top Dead Center (TDC) on the intake stroke, which helps push out remaining exhaust gases and cool the cylinder.

The intake valve opens slightly before the piston reaches Top Dead Center (TDC) to allow the incoming air-fuel mixture to start entering the cylinder earlier.

The air-fuel mixture enters the crankcase through a check valve due to a pressure difference created by the piston's upward movement.

The downward movement of the piston compresses the fuel-air mixture in the crankcase and forces it through the transfer port into the cylinder.

The exhaust port and transfer port are both covered when the piston moves upward, creating a partial vacuum in the crankcase.

Both the early opening and late closing of the exhaust valve contribute to better scavenging and cooling of the cylinder by removing exhaust gases and drawing in fresh air.

When the piston moves downwards on the intake stroke, the lower pressure inside the cylinder allows atmospheric pressure to push a large amount of air-fuel mixture into the cylinder.

The intake valve remains open until 45 degrees past Bottom Dead Center (BDC) to allow more time for the air-fuel mixture to enter the cylinder.