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

To determine how many degrees of crankshaft travel occur after ignition until the intake valve opens, you need to consider the timing of the ignition and the opening of the intake valve.

Ignition happens at 28° Before Top Dead Center (BTDC), and the intake valve opens at 15° BTDC. To find the degrees of crankshaft travel from the ignition point to when the intake valve opens, you can subtract the ignition point from the intake valve opening point.

In this case, the calculation would be:

1. Starting from the ignition at 28° BTDC,

2. The intake valve opens at 15° BTDC.

The sequence shows that after ignition at 28° BTDC, you would move to 0° (Top Dead Center), and then continue to 15° BTDC. Therefore, the amount of crankshaft travel would include moving from ignition to Top Dead Center (which is 28°) and then moving another 15° BTDC, resulting in:

• From 28° to 0° is 28° of crankshaft travel,

• From 0° to 15° BTDC adds another 15° of travel.

The total degrees of crankshaft travel from the point