BMEP Calculator
Enter torque, displacement, and stroke type to calculate BMEP — the standard metric for comparing engine efficiency regardless of size.
Engine Parameters
BMEP Result
BMEP (Imperial)
—
PSI
pounds per square inch
BMEP (Metric)
—
bar
— kPa
Efficiency Context
Enter values to see efficiency rating
Formula Used
BMEP = (Torque × 4π) / Displacement
(4-stroke, SAE units)
(4-stroke, SAE units)
Typical BMEP Values by Engine Type
| Engine Type | BMEP (PSI) | BMEP (bar) | Example |
|---|---|---|---|
| NA Gasoline (stock) | 150–175 | 10.3–12.1 | Small block V8 |
| Turbocharged Gasoline | 200–260 | 13.8–17.9 | Modern turbo 4-cyl |
| Heavy-Duty Diesel | 270–340 | 18.6–23.4 | Semi truck engine |
| High-Perf Race Engine | 300–380 | 20.7–26.2 | Formula car / drag |
Click any row to load example values into the calculator.
Summary
Enter torque, displacement, and stroke type to calculate BMEP — the standard metric for comparing engine efficiency regardless of size.
How it works
- Enter engine torque in lb-ft or Nm.
- Enter engine displacement in cubic inches (in³) or liters (L).
- Select 2-stroke or 4-stroke (affects the power stroke ratio per revolution).
- BMEP is calculated using the standard formula: BMEP = (Torque × 4π) / Displacement for 4-stroke, or (Torque × 2π) / Displacement for 2-stroke.
- Results are shown in PSI (imperial) and bar / kPa (metric) simultaneously.
Use cases
- Compare engine efficiency between different engine families without displacement bias.
- Benchmark a new engine build against known-good production engines.
- Evaluate turbo or supercharger effectiveness by checking BMEP before and after boost.
- Identify whether torque gains are from volumetric or thermal efficiency improvements.
- Academic and engineering coursework on internal combustion engine design.
- Verify engine simulation software output against hand calculations.
Frequently Asked Questions
Last updated: 2026-07-22 ·
Reviewed by Nham Vu