FORMULAS & TABLES

DISPLACEMENT OF EVOLUTION ENGINES:

##### BORE

3.498

3.625

3.780

Stock 80”

S & S

Sputhe

3.812

Sportster

73.268

78.685

85.557

4.250

Stock 80”

81.686

87.725

95.388

4.625

88.894

95.466

103.805

CALCULATING THE DISPLACEMENT OF A TWO CYLINDER ENGINE:

Displacement can be determined by the formula: D = B X B X S X 1.5708

 Where: D = Displacement B = Bore S = Stroke

CALCULATING COMPRESSION RATIO:

Compression ratio can be determined by the formula:

 C = D + Vd + Vs + Vc Vd + Vs + Vc

 Where: C = Compression ratio D = Displacement of one cylinder Vd = Volume of dish (+) or dome (-) on piston Vs = Volume of squish clearance Vc = Volume of combustion chamber

To calculate the compression ratio of an engine using Sputhe cylinders the following values may be used.

 D = 782cc for the 95.4” kit D = 850cc for the 103.8” kit Vd = 16cc for dish top pistons Vd = 0cc for the flat top pistons Vs = 11cc @ .060” clearance Vc = 78cc for pre 1990 heads Vc = 87cc for 1990 & up heads

Example: 1989 engine using a 95.4 ci kit with dish top pistons:

 C = D+Vd+Vs+Vc= 782cc+16cc+11cc+80cc= 897cc = 8.54 Vd+Vs+Vc 166cc+11cc+80cc 105cc 1

### FORMULAS FOR CALCULATING TORQUE & HORSEPOWER:

 T = Hp X 5252 Hp = T X rpm Rpm 5252

TABLE OF EQUIVALENTS:

 1 inch = 25.4 mm 1 cubic inch = 16.387cc 1 mm = 0.039371 inch 1 liter (1000cc) = 61.024 cubic inch

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