These guides explain the formulas, assumptions and engineering relationships behind the calculators on Auto Engineering Tools. Use them to understand what each input represents, follow worked examples and see how changes in one part of a vehicle can affect another.
Learn how engine RPM, transmission ratio, final-drive ratio and tire diameter combine to determine theoretical road speed. The guide includes the wheel-RPM relationship and a worked speed calculation.
See how changing tire diameter alters effective gearing, engine RPM at a given road speed and speedometer behavior. The guide explains why a larger tire effectively makes the overall gearing taller.
Understand how bore, stroke and cylinder count determine total engine displacement. The guide walks through the cylinder-volume formula and shows how the result is expressed in cubic inches, cubic centimeters and liters.
Learn how swept volume and clearance volume determine static compression ratio, including the effects of combustion-chamber volume, head-gasket volume, piston dish or dome and deck clearance.
Understand the mathematical relationship between torque, engine speed and horsepower, including the 5252 constant, inverse torque calculation and the distinction between calculated values and dyno measurements.
The guides provide the reasoning and worked examples behind the calculations, while the calculators make it easier to evaluate your own dimensions and ratios. For planning and analysis, compare calculated results with the specifications and measurements for the actual vehicle or components being evaluated.