{
  "id": "engine-displacement",
  "version": "1c1fdeb76781",
  "status": "published",
  "name": "Engine Displacement Calculator",
  "question": "What is the engine displacement?",
  "summary": "Computes engine displacement from bore, stroke and the number of cylinders, in cubic centimetres (cc), litres and cubic inches.",
  "category": "physics",
  "subcategory": "mechanics",
  "url": "https://www.acalculator.org/physics/engine-displacement-calculator",
  "markdown": "https://www.acalculator.org/physics/engine-displacement-calculator.md",
  "kind": "function",
  "method": "Displacement = π ÷ 4 × bore² × stroke × cylinders; litres = cc ÷ 1,000; cubic inches = cc ÷ 16.387064.",
  "assumptions": [
    "Displacement is the swept volume only: the combustion chamber above the piston at the top of its stroke is not included.",
    "Every cylinder has the same bore and stroke.",
    "1 in = 2.54 cm exactly, so 1 in³ = 16.387064 cm³."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "bore": {
        "title": "Bore",
        "description": "The diameter of one cylinder.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 5
      },
      "stroke": {
        "title": "Stroke",
        "description": "How far the piston travels from the bottom to the top of the cylinder.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 5
      },
      "cyl": {
        "title": "Cylinders",
        "description": "How many cylinders the engine has.",
        "type": "integer",
        "minimum": 1,
        "maximum": 24
      }
    }
  },
  "outputs": {
    "cc": {
      "label": "Displacement (cc)",
      "description": "The swept volume of all cylinders, in cubic centimetres.",
      "format": "number"
    },
    "liters": {
      "label": "Displacement (L)",
      "description": "The same volume in litres: cc ÷ 1,000.",
      "format": "number"
    },
    "cubicInches": {
      "label": "Displacement (in³)",
      "description": "The same volume in cubic inches: cc ÷ 16.387064.",
      "format": "number"
    },
    "perCylinder": {
      "label": "Per cylinder (cc)",
      "description": "The swept volume of one cylinder: π ÷ 4 × bore² × stroke.",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "bore": 0.1016,
      "stroke": 0.088392,
      "cyl": 8
    },
    "outputs": {
      "cc": 5732.97759902541,
      "liters": 5.732977599025411,
      "cubicInches": 349.8477579037594,
      "perCylinder": 716.6221998781763
    },
    "text": "A 8-cylinder engine with this bore and stroke displaces 5,733 cc (5.73 L, 349.8 in³)."
  },
  "examples": [
    {
      "given": {
        "bore": 0.1016,
        "stroke": 0.088392,
        "cyl": 8
      },
      "expect": {
        "cubicInches": 349.8477579037594,
        "cc": 5732.97759902541,
        "liters": 5.73297759902541
      },
      "source": "Cylinder volume π × r² × h (OpenStax, Prealgebra 2e, §9.6 Solve Geometry Applications: Volume and Surface Area). https://openstax.org/books/prealgebra-2e/pages/9-6-solve-geometry-applications-volume-and-surface-area; hand calculation in content.mdx: π ÷ 4 × 4² × 3.48 × 8 = 349.85 in³ × 16.387064 = 5,732.98 cc"
    },
    {
      "given": {
        "bore": 0.08600000000000001,
        "stroke": 0.08600000000000001,
        "cyl": 4
      },
      "expect": {
        "cc": 1998.2288568717092,
        "perCylinder": 499.5572142179273
      },
      "source": "Cylinder volume π × r² × h (OpenStax, Prealgebra 2e, §9.6 Solve Geometry Applications: Volume and Surface Area). https://openstax.org/books/prealgebra-2e/pages/9-6-solve-geometry-applications-volume-and-surface-area; hand calculation in content.mdx: π ÷ 4 × 8.6² × 8.6 × 4 = 1,998.23 cc"
    },
    {
      "given": {
        "bore": 0.1,
        "stroke": 0.12732395447351627,
        "cyl": 1
      },
      "expect": {
        "cc": 1000,
        "liters": 1
      },
      "source": "Cylinder volume π × r² × h (OpenStax, Prealgebra 2e, §9.6 Solve Geometry Applications: Volume and Surface Area). https://openstax.org/books/prealgebra-2e/pages/9-6-solve-geometry-applications-volume-and-surface-area; hand calculation in content.mdx: π ÷ 4 × 10² × (40 ÷ π) = 1,000 cm³",
      "tolerance": 1e-12
    }
  ],
  "sources": [
    "OpenStax, Prealgebra 2e, §9.6 Solve Geometry Applications: Volume and Surface Area (volume of a cylinder V = π r² h). https://openstax.org/books/prealgebra-2e/pages/9-6-solve-geometry-applications-volume-and-surface-area (retrieved 2026-10-01)",
    "NIST Handbook 44 (2026), Appendix C, General Tables of Units of Measurement: 1 in = 2.54 cm; 1 in³ = 16.387064 cm³; 1 L = 1,000 cm³. https://www.nist.gov/document/2026-nist-handbook-44-appendix-c (retrieved 2026-10-01)"
  ],
  "related": [
    "compression-ratio",
    "gear-ratio",
    "power"
  ],
  "changelog": []
}