Section IV. ENGINE MEASUREMENTS

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Figure 2-40. F-Head Engine

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TM-9-8000 Principles of Automotive Vehicles Manual

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Vacuum In Cylinder on Intake Stroke.

TM 9-8000

c. Horizontal Opposed (C, Fig. 2-41). Less

d. Radial (D, Fig. 2-41). The radial engine has

common than the in-line and the V-type, this engine is

cylinders placed in a circle around the crankshaft. The

designed to fit in compartments where height is a

crankshaft has only one throw, with one of the pistons

consideration.

The cylinders are arranged at 180

connected to this throw by a master rod. The connecting

degrees to each other with opposing cylinders sharing a

rods from the other pistons are fastened to the

common crankshaft journal. This engine arrangement

crankshaft through this master rod. This engine is

almost always is used for air-cooled configurations,

almost exclusively an aircraft engine and is of little

although at least one auto manufacturer is using a

interest when studying automotive technology.

horizontal- ly opposed, water-cooled engine in their

product.

Section IV. ENGINE MEASUREMENTS

Area of cylinder bore =

2-20. Bore and Stroke (Fig. 2-42).

0.785xdiameter = 0.785D

a. Bore. The bore is the diameter of the cylinder.

Area of cylinder bore =

0.785x4 = 0.785x16 =12.56

b. Stroke. The stroke is the distance that the piston

travels as it moves from top dead center to bottom dead

Area of cylinder bore =

center.

12.56 sq in.(81 .02 sq cm).

2-21.

Piston Displacement (Fig.

2-42).

Piston

Multiply the area of the cylinder bore by the

displacement is the volume of space that the piston

stroke.

displaces as it moves from top dead center to bottom

dead center. The piston displacement is used to express

12.56sqin.x3in. =

engine size. To find the displacement of an eight-

37.68cu in.(617.37cc)

cylinder engine with a bore of 4 in. (10.16 cm) and a

stroke of 3 in. (7.62 cm), do the following.

This is the piston displacement for one cylinder.

a. Find the area of the cylinder bore. To find the

c. Multiply the displacement of one cylinder by

area of the cylinder bore, use the formula:

he number of cylinders that the engine has.

Figure 2-42. Bore, Stroke, and Displacement

2-27