How many degrees of crankshaft travel after ignition does the intake valve open if ignition occurs at 28° BTDC and the intake valve opens at 15° BTDC?

To determine how many degrees of crankshaft travel after ignition the intake valve opens, it's essential to consider the timing of both events in terms of their position relative to the crankshaft. Ignition occurs at 28 degrees before top dead center (BTDC), while the intake valve opens at 15 degrees BTDC.

To find the crankshaft travel in degrees after ignition to the point the intake valve opens, you can calculate the difference between the two angles:

• Start with the ignition event at 28° BTDC.

• The intake valve opens at 15° BTDC.

The differential in crankshaft travel is determined as follows:

1. Since 15° BTDC is closer to top dead center than 28° BTDC, you will calculate the clockwise movement from the ignition point to the intake valve opening point. This means you will go from 28° to 15°.

2. The travel can be calculated by taking the difference:

• 28° - 15° = 13 degrees BTDC.

However, since we are concerned with crankshaft movement after ignition toward the intake event, we interpret it from the perspective of how far the crankshaft moves in the clockwise direction after the ignition point until the intake valve