Overhead Cam vs. Overhead Valve Cylinder Heads
If you are a car enthusiast or a mechanic, you may have heard about the terms “overhead cam” (OHC) and “overhead valve” (OHV) when it comes to cylinder heads. Both of these designs have been around for decades and have their pros and cons. In this article, we’ll explore the differences between the two and help you determine which is better for your engine.
What Are Cylinder Heads and Why Do They Matter?
Before we dive into the differences between OHC and OHV cylinder heads, let’s first discuss what cylinder heads are and why they matter. Cylinder heads are a vital part of an engine’s combustion process. They sit on top of the engine block and cover the cylinders. They contain the intake and exhaust valves, which open and close to let air and fuel in and exhaust gases out of the engine. Cylinder heads also house the spark plugs, which ignite the air-fuel mixture and start the combustion process.
The design of the cylinder head plays a significant role in an engine’s performance, fuel efficiency, and emissions. That’s why it’s essential to choose the right type of cylinder head for your engine.
What Is an Overhead Valve (OHV) Cylinder Head?
An overhead valve (OHV) cylinder head, also known as a pushrod engine, is a traditional design that has been around for many years. In an OHV engine, the camshaft is located inside the engine block, and pushrods are used to actuate the valves. The pushrods transfer the motion of the camshaft to the rocker arms, which, in turn, open and close the valves.
OHV cylinder heads have a simple and robust design, which makes them less expensive to produce than OHC cylinder heads. They also have fewer moving parts, which means they require less maintenance. However, OHV engines tend to be less efficient and have lower power output than OHC engines.
What Is an Overhead Cam (OHC) Cylinder Head?
An overhead cam (OHC) cylinder head, also known as a single or double overhead cam engine, is a more modern design that has gained popularity in recent years. In an OHC engine, the camshaft(s) is located in the cylinder head, directly above the valves. The camshaft(s) actuate the valves directly, without the need for pushrods or rocker arms.
OHC cylinder heads offer several advantages over OHV cylinder heads. They have a more compact design, which allows for a smaller and lighter engine. OHC engines tend to be more efficient and have higher power output than OHV engines. However, OHC engines are more expensive to produce and require more maintenance.
Which Is Better: OHC or OHV Cylinder Heads?
The answer to this question depends on several factors, including the type of engine, the intended use of the vehicle, and personal preferences. Here are some things to consider when choosing between OHC and OHV cylinder heads:
Engine Type
OHC engines are generally better suited for high-performance and sports cars, while OHV engines are better suited for trucks and SUVs. This is because OHC engines tend to have higher power output and rev higher, while OHV engines offer more low-end torque.
Fuel Efficiency
OHC engines are generally more fuel-efficient than OHV engines. This is because they have a more efficient combustion process and use less fuel to produce the same amount of power.
Maintenance
OHV engines require less maintenance than OHC engines. This is because they have fewer moving parts and are generally simpler in design.
Performance
OHC engines tend to have higher power output and rev higher than OHV engines. This makes them ideal for high-performance and sports cars that require high RPMs. However, OHV engines offer more low-end torque, which is beneficial for towing and off-road applications.
Weight and Size
OHC engines are generally more compact and lighter than OHV engines. This makes them ideal for applications where space is limited, such as in sports cars and motorcycles.
Emissions
OHC engines are generally cleaner-burning than OHV engines. This is because they have a more efficient combustion process and produce fewer emissions.
Conclusion
In summary, both OHC and OHV cylinder heads have their pros and cons. The choice between the two depends on the type of engine, the intended use of the vehicle, and personal preferences. If you’re looking for a high-performance engine for your sports car, an OHC engine may be the way to go. On the other hand, if you’re looking for a reliable and efficient engine for your truck or SUV, an OHV engine may be the better choice.
FAQs
- What is the difference between an OHC and OHV engine?
- Which is more fuel-efficient, an OHC or OHV engine?
- Do OHC engines require more maintenance than OHV engines?
- Are OHC engines better for high-performance applications?
- Which is better for towing, an OHC or OHV engine?
1. What is the difference between an OHC and OHV engine?
The main difference between an OHC and OHV engine is the location of the camshaft. In an OHC engine, the camshaft is located in the cylinder head, while in an OHV engine, the camshaft is located in the engine block.
2. Which is more fuel-efficient, an OHC or OHV engine?
OHC engines are generally more fuel-efficient than OHV engines. This is because they have a more efficient combustion process, which results in better fuel economy.
3. Do OHC engines require more maintenance than OHV engines?
OHC engines can require more maintenance than OHV engines. This is because they have more components, such as timing belts and tensioners, that need to be replaced at regular intervals. However, this also depends on the specific engine and its maintenance requirements.
4. Are OHC engines better for high-performance applications?
OHC engines are generally better for high-performance applications, as they tend to have higher power output and can rev higher than OHV engines. This makes them ideal for sports cars and other performance vehicles.
5. Which is better for towing, an OHC or OHV engine?
OHV engines are generally better for towing, as they offer more low-end torque, which is beneficial for heavy towing and off-road applications. However, this also depends on the specific engine and its towing capabilities.