{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://askcalculators.com/us/engine-horsepower/schema.json",
  "title": "Estimate Engine Output from Torque and RPM inputs",
  "description": "Calculate engine power from measured torque and speed, with displacement-specific output and an explicit legacy airflow fallback.",
  "type": "object",
  "properties": {
    "displacement": {
      "title": "Displacement (L)",
      "type": "number",
      "default": 5,
      "minimum": 0.01
    },
    "cylinders": {
      "title": "Cylinders",
      "type": "number",
      "default": 8,
      "minimum": 1
    },
    "rpm": {
      "title": "Engine speed (RPM)",
      "type": "number",
      "default": 6000,
      "minimum": 0
    },
    "efficiency": {
      "title": "Legacy airflow efficiency (used only without torque)",
      "type": "number",
      "default": 0.85,
      "minimum": 0.01
    },
    "torqueNm": {
      "title": "Measured torque at entered RPM (N·m, optional)",
      "type": "number",
      "description": "When provided, torque and RPM replace the legacy airflow heuristic.",
      "minimum": 0
    }
  },
  "required": [
    "displacement",
    "cylinders",
    "rpm",
    "efficiency"
  ],
  "additionalProperties": false,
  "x-askcalculators": {
    "version": "20.13.0",
    "calculatorUrl": "https://askcalculators.com/us/engine-horsepower/",
    "queryExample": "https://askcalculators.com/us/engine-horsepower/?displacement=2&cylinders=4&rpm=4000&efficiency=0.85&torqueNm=300",
    "migrationStatus": "new",
    "reviewStatus": "pending",
    "pageStatus": "live",
    "workStatus": "pending",
    "formula": {
      "expression": "Power (W) = torque (N·m) × RPM × 2π / 60; mechanical hp = W / 745.699871582.",
      "note": "Without torque: legacy airflow hp = litres × 61.0237 × RPM × efficiency / 3456 / 1.4."
    },
    "quality": {
      "availability": "live",
      "technicalReviewRecord": "/reviews/engine-horsepower-calculator.json",
      "qualifiedReview": "pending",
      "qualifiedReviewer": null,
      "qualifiedReviewDate": null,
      "formulaVersion": "20.13.0",
      "referenceCoverage": "references-pending",
      "releaseTestScope": "Catalog and regression checks are not a professional formula audit; consult release evidence.",
      "historicalMetadataDate": "2026-09-10",
      "historicalMetadataNotice": "The imported date is not evidence of a completed human review."
    },
    "outputs": {
      "horsepower": {
        "title": "Mechanical horsepower",
        "type": "number",
        "x-format": "number",
        "x-digits": 2,
        "x-primary": true
      },
      "kilowatts": {
        "title": "Power (kW)",
        "type": "number",
        "x-format": "number",
        "x-digits": 2
      },
      "horsepowerPerLitre": {
        "title": "Horsepower per litre",
        "type": "number",
        "x-format": "number",
        "x-digits": 2
      },
      "litresPerCylinder": {
        "title": "Litres per cylinder",
        "type": "number",
        "x-format": "number",
        "x-digits": 2
      }
    }
  }
}