OHV vs OHC vs SOHC vs DOHC Engines | Differences Explained
May 06, 2025If you’ve ever read about engine specs, you’ve likely seen terms like OHV, OHC, SOHC, and DOHC. But what do they actually mean? How do these camshaft and valvetrain designs affect performance, efficiency, and durability? This guide explains each type clearly and compares their pros and cons.
OHV vs OHC vs SOHC vs DOHC: What’s the Difference and Which Is Better?
What Is an OHV Engine? (Overhead Valve)
OHV stands for Overhead Valve. Also known as a pushrod engine, the camshaft is located inside the engine block. It uses lifters, pushrods, and rocker arms to open and close the valves in the cylinder head.
-
Advantages:
-
Compact size, suitable for smaller engine bays
-
High torque at low RPM (ideal for trucks & muscle cars)
-
Simple and durable design
-
-
Disadvantages:
-
Limited high-RPM performance
-
Fewer valves per cylinder compared to modern OHC engines
-
Example: Many classic American V8 engines (Chevy Small Block, Chrysler HEMI).
What Is an OHC Engine? (Overhead Camshaft)
OHC means Overhead Camshaft. Unlike OHV, the camshaft is mounted in the cylinder head, directly above the valves. This eliminates the need for pushrods and allows for more precise valve timing.
-
Advantages:
-
Better airflow and efficiency
-
Higher RPM capability
-
Allows for multi-valve configurations
-
-
Disadvantages:
-
More complex and expensive to manufacture
-
Larger engine head size
-
SOHC (Single Overhead Camshaft)
SOHC stands for Single Overhead Camshaft. Each cylinder bank has one camshaft controlling both intake and exhaust valves.
-
Advantages:
-
Simpler than DOHC, fewer moving parts
-
Reliable and cost-effective
-
Easier maintenance
-
-
Disadvantages:
-
Limited flexibility for valve timing
-
Usually restricted to 2 valves per cylinder
-
Example: Honda’s early Civic and Accord engines.
DOHC (Double Overhead Camshaft)
DOHC means Double Overhead Camshaft. Each cylinder bank has two camshafts: one for intake valves and one for exhaust valves. Most DOHC engines also feature 4 valves per cylinder (2 intake, 2 exhaust).
-
Advantages:
-
Superior airflow and power output
-
Supports variable valve timing (VVT) technologies
-
Excellent for high-RPM performance
-
-
Disadvantages:
-
More complex and costly to maintain
-
Larger engine head, less compact
-
Example: Modern Honda VTEC, BMW M engines, Toyota 2JZ.
| Engine Type | Camshaft Location | Typical Valves | Advantages | Disadvantages |
|---|---|---|---|---|
| OHV (Pushrod) | In engine block | 2 per cylinder | Compact, high torque, durable | Limited high RPM, less efficient |
| OHC | Cylinder head | 2–4 per cylinder | Better timing precision, higher RPM | More complex, larger size |
| SOHC | Cylinder head (1 camshaft) | Usually 2 | Simpler, cost-effective | Limited flexibility, fewer valves |
| DOHC | Cylinder head (2 camshafts) | 4 per cylinder | High performance, supports VVT | Expensive, complex |
The main difference is in the placement of the camshaft. OHV means Over Head Valve. Although almost all modern car engines have valves placed in the cylinder head, the term OHV is used to describe a pushrod engine, with the camshaft placed in the cylinder block. OHC stands for Over Head Cam, or the camshaft is installed in the cylinder head. SOHC means Single Overhead Cam, while DOHC means Double Overhead Cam.
Which One Is Better?
There’s no single winner—it depends on the application:
-
OHV (Pushrod): Best for muscle cars, trucks, and applications where torque matters.
-
SOHC: Balanced option for reliable, affordable engines.
-
DOHC: Dominates modern performance and efficiency due to multi-valve flexibility and advanced timing.
Muscle car fans often prefer old-school OHV V8s, while modern performance enthusiasts love DOHC twin-cam designs.
FAQs (People Also Ask Optimization)
Q: Is DOHC always better than SOHC?
Not always. DOHC offers more performance, but SOHC engines are simpler and cheaper to maintain.
Q: Why are pushrod (OHV) engines still used?
Because they are compact, reliable, and produce great low-end torque—ideal for trucks and American V8s.
Q: Which engine type is most fuel-efficient?
Typically DOHC, since it supports more advanced valve timing and better airflow.
Conclusion
The main difference between OHV, OHC, SOHC, and DOHC lies in camshaft placement and valve operation. Each design has unique strengths: OHV engines are compact and torquey, SOHC is reliable and simple, while DOHC leads in modern performance and efficiency.
If you want to see these designs in action, check out the Cison OHV engine model now available at enginediy. Perfect for learning engine history and mechanics hands-on.