One of the key aspects that distinguishes each variant is the cylinder head designation, which determines performance potential, valve size, and VTEC configuration.
In this post, we’ll explore the Honda B-Series Cylinder Head Designation Chart in detail, covering every major variant, including casting codes, combustion chamber sizes, VTEC compatibility, and flow characteristics.
Honda B Series Engine Cylinder Head Designation Chart
| Cylinder Head Code | Engine Origin | VTEC | Valve Size (Int/Exh mm) | Combustion Chamber (cc) | Port Shape | Ideal Block Compatibility |
|---|---|---|---|---|---|---|
| PR3 | B16A (JDM/USDM), B17A | Yes | 33 / 28 | ~42.7 | Round | B16A, B18C |
| PR3-1 | Early B16A (JDM EF9/DA6) | Yes | 33 / 28 | ~42.5 | Round | B16A, B18C |
| PR3-2 | B16A SiR-II (EG6) | Yes | 33 / 28 | ~42.5 | Round | B16A, B18C |
| PR3-3 | B16A SiR-II (EK4) | Yes | 33 / 28 | ~42.7 | Round | B16A, B18C |
| PR9 | B17A1 (USDM GSR 92–93) | Yes | 33 / 28 | ~42.7 | Round | B17A, B18C |
| P72 | B18C1 (GSR), B18C5 (Type R) | Yes | 33 / 28 | ~42.7 | Oval | B18C, B18B |
| P73 | B18C (JDM Type R) | Yes | 33 / 28 | ~42.5 | Oval | B18C, B16A |
| PR6 | B16B (Civic Type R EK9) | Yes | 33 / 28 | ~42.5 | Oval | B16B, B18C |
| PR8 | B16A2 (Civic Si), B16A3 (Del Sol) | Yes | 33 / 28 | ~42.7 | Round | B16A, B18C |
| P80 | B18C (European GSR) | Yes | 33 / 28 | ~42.7 | Oval | B18C, B18B |
| P8R | B20Z, B20B (Japan) | No | 33 / 28 | ~45 | Oval | B20B, B18B |
| PR4 | B18A1, B18B1 (USDM) | No | 31 / 27.5 | ~45 | Oval | B18A/B, B20B |
| P75 | B18B1 (OBD2) | No | 31 / 27.5 | ~45 | Oval | B18B, B20B |
| P91 | B20B (Low Compression JDM) | No | 31 / 27.5 | ~45 | Oval | B20B |
| P95 | B20Z2 (USDM CR-V 99–01) | No | 31 / 27.5 | ~45 | Oval | B20Z, B18B |
| P94 | B18C4 (UKDM/Euro GSR) | Yes | 33 / 28 | ~42.7 | Oval | B18C, B18B |
| P90 | B18B (JDM OBD0 Non-VTEC) | No | 31 / 27.5 | ~45 | Oval | B18B, B20B |
| P72-2 | B18C Type R (USDM) | Yes | 33 / 28 | ~42.5 | Oval | B18C |
| PR3-A | B16A JDM SiR | Yes | 33 / 28 | ~42.7 | Round | B16A |
| PR3-B | B16A2 (OBD2) | Yes | 33 / 28 | ~42.7 | Round | B16A, B18C |
| P71 | B18C (ASEAN Spec GSR) | Yes | 33 / 28 | ~42.7 | Oval | B18C |
| P77 | B16A (Civic Ferio, JDM Auto) | Yes | 33 / 28 | ~42.5 | Round | B16A |
| PR5 | B16A1 (OBD0 JDM) | Yes | 33 / 28 | ~42.5 | Round | B16A |
| P92 | B18B (South American Spec) | No | 31 / 27.5 | ~45 | Oval | B18B, B20B |
| P86 | B18A (Early OBD0) | No | 31 / 27.5 | ~45 | Oval | B18A |
| P74 | B18C (Japanese GSR) | Yes | 33 / 28 | ~42.5 | Oval | B18C |
| P79 | B18B1 (Canadian CR-V) | No | 31 / 27.5 | ~45 | Oval | B18B, B20B |
| P70 | B18C2 (AUS/NZ Spec GSR) | Yes | 33 / 28 | ~42.7 | Oval | B18C |
| P84 | B16A2 (ASEAN Market) | Yes | 33 / 28 | ~42.7 | Round | B16A |
| P85 | B16A (SiR-II Auto) | Yes | 33 / 28 | ~42.5 | Round | B16A |
| PR7 | B16B (Special EK9 JDM Race Variant) | Yes | 33 / 28 | ~42.5 | Oval | B16B, B18C |
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Key Technical Differences Between Heads
1. Port Design
- PR3 & PR9 – Circular ports, high airflow, ideal for high RPM applications.
- P72 & P73 – Slightly oval ports for balanced low and high RPM performance.
- PR4, P75 & P8R – Oval ports, optimized for torque and street drivability.
2. Combustion Chamber Volume
- Smaller chambers (~42.5 cc) in PR3/P72 improve compression, making them ideal for VTEC engines.
- Larger chambers (~45 cc) in PR4/P75 heads lower compression, providing boost-friendly setups.
3. Valve Size & Flow
- P8R stands out among non-VTEC heads for having 33 mm intake valves, equal to VTEC heads.
- PR4 and P75 use smaller valves, limiting top-end power but increasing low-end response.
4. VTEC vs. Non-VTEC
- VTEC heads (PR3, P72, P73) allow aggressive cam profiles for high performance.
- Non-VTEC heads (PR4, P75) are better for boost or torque-heavy builds.
- Hybrid LS/VTEC setups pair a non-VTEC block (like B18B) with a VTEC head (PR3 or P72) for the best of both worlds.
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Choosing the Right Cylinder Head
When selecting a B-series cylinder head for your project, consider the following:
- For All-Motor Builds:
- Choose PR3 or P72 heads, they flow best at high RPM and support strong camshaft upgrades.
- For Turbo Builds:
- The P75 or P8R heads work well due to larger combustion chambers and smoother port transitions.
- For Budget Performance (LS/VTEC):
- Use a P72 or PR3 head on a B18B block. You’ll need to modify the oil feed, dowel pin alignment, and ECU tuning for VTEC activation.
- For OEM Restoration:
- Match head code to your block, for example, B16A → PR3, B18C → P72, B18B → PR4.
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Popular B-Series Head Swaps
| Common Build | Head | Block | Resulting Performance |
|---|---|---|---|
| LS/VTEC | PR3 or P72 | B18B | 180–200+ hp, strong mid-top range |
| B20/VTEC | P72 or PR3 | B20B/Z | 190–210+ hp, high torque + VTEC punch |
| GSR/Type R Hybrid | P73 | B18C | Excellent high-RPM flow, ideal for track use |
Final Thoughts
The Honda B-Series cylinder head designations are more than just codes, they’re blueprints for performance. Each head brings unique flow dynamics and combustion traits that define the engine’s character. Whether you’re chasing a high-revving track monster or a torquey daily driver, understanding these cylinder head differences helps you build smarter and faster.
From the precision of the PR3 and P72 VTEC heads to the durability of P75 non-VTEC castings, every B-series head has its place in Honda’s tuning history. Combine the right head and block, and you’ll unlock the legendary performance potential that made the B-series an icon in the JDM world.
