Estimated Power:

BHP = PLAN/33,000

where:

P = BMEP, in PSI

L = piston stroke, measured in feet

A = Area of one piston, in square inches

N = Number of power strokes per minute

BMEP(Brake Mean Effective Pressure)

BMEP = (HP*13000)/(L*RPM)

Where:

HP = Horsepower

L = Displacement in Liters(1 ci. = 16.39 cc = .01639L)

Rod/Stroke Ratio:

A = L/S

Where

L = Rod Length (in inches)

S = Stroke (in inches)

Piston Acceleration:

Gmax = ((N^2*L)/2189)(1+1/(2A))

Where:

Gmax = max. piston acceleration, in feet/sec squared

N = Crankshaft speed, in RPM

L = stroke, in inches

A = Rod Ratio

Piston Travel vs. Crank Rotation:

d = ((S/2)+L)-(S/2 cos X) - L sin [cos-1(S/2L sin X)]

WHere:

S = Stroke (mm)

L = Rod Length (mm)

X = Crank Angle before of after TDC (in degrees)

Piston Speed:

Cm = .166*LN

Where:

Cm = Mean piston speed, in feet per minute

L = Stroke (in inches)

N = Crankshaft speed (RPM)

Piston Stroke Motion:

S = (R cos X)+(L cos Z)

Where:

S = Distance of piston wrist pin from center of crankshaft

R = Radius of wrist pin

L = Length of Rod

X = Angle of wrist pin

Z = Angle of the rod

Compression Ratio:

CR = (V1+V2)/V2

Where:

CR = Compression ratio

V1 = Cylinder volume at exhaust closing

V2 = Combustion Chamber volume

Port Open Time:

T = (60/N)(Z/360)

Where:

T = Time in seconds

N = Crankshaft Speed (RPM)

Z = Port open duration, in degrees

MPH Calculate:

MPH = (RPM*D)/(R*336)

Where:

RPM = Engine RPM

D = Wheel Diameter (in inches)

R = Gear Ratio

RPM Calculate:

RPM = (MPH*R*336)/D

Where:

MPH = Speed

R = Gear Ratio

D = Tire Diameter (in inches)

Here's a few more - these will allow you to compute the compression ratio of an engine:

CR = (V1 + V2)/V2

Where:

CR = Compression Ratio

V1 = Cylinder Volume (in cubic centimeters (cc))

V2 = Cylinder Head Volume (in cubic centimeters (cc))

V1 = (B^2 * (pi/4) * S)/1000

Where:

B = Bore (in mm)

pi = 3.1416

S = Stroke (in mm)

V2 = HV + DV + V3

Where:

HV = Cylinder Chamber Volume (in cubic centimeters (cc))

DV = Piston Dish Volume (in cubic centimeters (cc))

V3 = Slice (or Squish) Volume (in cubic centimeters (cc))

V3 = B^2 * (pi/4) * (G - DC)

Where:

G = Head Gasket Thickness (crushed) (in mm)

DC = Deck Clearance (in mm)

Formula for Engine Displacement:

D = (B^2 * S * (pi/4))*n

Where

D = Engine Displacement (in cc)

B = Cylinder Bore (in mm)

S = Stroke (in mm)

n = number of cylinders

Formulas for brake horsepower

Horsepower:

HP = rpm x T / 5252

Where:

HP = Horsepower

RPM = Engine speed (RPM)

T = Engine Torque (in lb*ft)

Torque:

T = 5252 x horsepower / rpm

ALSO - HP = Torque (Nm) x RPM / 7120.6616

Brake Specific Fuel Consumption

BSFC = F / BHP

Where:

F = Fuel (lbs/hr)

BHP = Brake Horsepower

BHP loss based on elevation:

L = E/1000 * 0.03 * BHP

Where:

L = BHP loss

E = elevation in feet

BHP = BHP at sea level