{
  "tool": "piston-ring-clearance-calculator",
  "version": "1.0.0",
  "author": "Bryan Terry, Van Buren AR",
  "date": "2026-07-17",
  "description": "Calculates required cold ring gap based on cylinder bore, material pair, and operating delta-T. Based on linear thermal expansion principles.",
  "materials": {
    "gray_iron_block": {
      "name": "Gray Iron (Block)",
      "alpha_linear": 10.8,
      "unit": "µm/m·°C",
      "wikidata_ref": "Q1055770"
    },
    "aluminum_block": {
      "name": "Aluminum Alloy (Block)",
      "alpha_linear": 23.1,
      "unit": "µm/m·°C",
      "note": "Typical hypoeutectic Al-Si alloy"
    },
    "cast_iron_ring": {
      "name": "Cast Iron Ring",
      "alpha_linear": 11.0,
      "unit": "µm/m·°C"
    }
  },
  "formula": {
    "cold_gap_required": "gap_cold = (α_block - α_ring) × ΔT × π × bore_diameter",
    "variables": {
      "gap_cold": "Required gap at room temp (mm)",
      "alpha_block": "Linear expansion of cylinder wall (µm/m·°C)",
      "alpha_ring": "Linear expansion of ring material (µm/m·°C)",
      "delta_T": "Operating temp minus ambient (°C)",
      "bore_diameter": "Nominal cylinder bore (mm)"
    },
    "sources": [
      "ASME Boiler and Pressure Vessel Code, Section II",
      "Engineering Toolbox: Thermal Expansion Coefficients"
    ]
  }
}