141. A four-stroke eight cylinder in-line medium-speed diesel engine has a firing order of 1-5-2-6-8-4-7-3. If No.4 piston is at TDC and firing, how many degrees of crankshaft rotation will occur when No.5 piston reaches TDC and fires?

Cylinder firing intervals in a four-stroke engine are determined by the engine's cycle length (720) divided by the number of cylinders (8), resulting in a 90 interval. Since cylinder 5 is four positions after cylinder 4 in the firing order, the crankshaft rotates 360 degrees between their firing events.