There are different types of cylinder heads that a vehicle can use. These offer varying benefits in terms performance, cost, and durability. Most of the time also, one type of head will fit one application and not the other. For more about the cylinder head types, read this section to the end. I will also be explaining the cylinder head manufacturing process and the materials used to make them.
Types of Cylinder Heads
Engine cylinder heads are commonly classified according to their design, and come in different shapes and configurations. The heads are also categorized by the type of material and their number in the engine. With that in mind, let’s now see the different types of cylinder heads as used in automobiles today.
Based on the Cylinder Head Design
Classification by design mainly follows the arrangement of valve train parts and intake/exhaust ports. That gives rise to these main types of cylinder heads.
- Flathead Cylinder Head
This is an earlier design and that had its drawbacks. It consists of a single cast block that features a very simple design. Flathead cylinder heads are easy manufacture, since they do not contain many parts. They are also lightweight enough and cheap in terms of cost.
The disadvantages of flathead type include the inefficient intake and exhaust passageways. The intake gases follow a 90-degree port, which leads to poor combustion of the fuel-air mixture. The exhaust gases also remain in the head’s channels for far too long, causing cooling problems.
- Overhead Valve Cylinder Head
Also known by other name as the I type cylinder head, this one uses a more complex construction with many different channels and ports. It houses several components such as parts of the valve train, spark plugs, fuel injectors, and more.
The I cylinder head offers many advantages in terms of performance and allows the engine to run better. This type of head is also provides for a better engine timing system, since it allows the camshaft and crankshaft to be close to each other.
- Overhead Camshaft Cylinder Head
This type of cylinder head derives its name from the position of the camshaft. It houses the camshaft, unlike the other heads described above. Additionally, it contains the valve train parts, spark plugs, and intake/exhaust passageways.
Overhead camshaft cylinder heads offer better channels for intake and exhaust gases. As a result, they perform well in ensuring proper combustion in the chambers and efficient exit of exhaust. That in turn, means optimal engine power, reduced emissions, and effective cooling.
Based on the Cylinder Head Material
Auto cylinder heads are made from different materials. Each material has its advantages when used in different applications. There are also disadvantages too, which makes material selection an important aspect. In that regard, the types of cylinder heads based on material include the following.
- Cast Iron Cylinder Head
These are made from a block of cast iron. The material offers several benefits. Cast iron cylinder heads are easy and less costly. They are also sturdy owing to the material’s superior strength. Iron also withstands higher temperatures well, which is one of the requirements for cylinder head material properties.
The downsides of iron cylinder heads include their heavy weight which can cause fuel economy and braking issues. Iron is also not as effective when it comes to dissipating heat. These types of heads are, therefore, normally suited for water-cooled engine systems.
It’s also worth mentioning a type of iron head called compacted graphite cylinder head. These are made by compacting powdered iron alloys under extremely high pressures. The material produces lightweight heads that also offer sound absorbing properties. These types of cylinder heads are commonly used on diesel engines.
- Aluminum Cylinder Head
Aluminum cylinder heads are the most preferred types today. They are more lightweight and do not add an unnecessary load to the engine. The heat conductivity of aluminum is also higher, which helps prevent localized hotspots and greatly helps with cooling.
Other advantages of aluminum heads include the material’s ability to sustain higher temperature levels. That means higher combustion temperatures, and reduced NOX emissions from the exhaust.
Aluminum heads are not without disadvantages. They are more difficult and costly to manufacture in addition to the higher prices for the material. Aluminum also warps easily in heat and is more prone to wear than the other cylinder head materials.
Based on the Number of Cylinder Heads
Depending on the type of engine and the required serviceability, the cylinder head can be a one-piece assembly or multiple pieces. These types of cylinder heads are explained below.
- Single Piece Cylinder Head
This type covers the entire engine block using one head. Single cylinder head assemblies are easy to manufacture using the casting process. Due to their design, these heads also add to the structural strength of the engine.
The main disadvantage of single piece cylinder heads is the amount of creep that they are subjected to. They tend to expand and contact more, sliding over and damaging the sealing gasket. Servicing engines that use these heads is also unnecessarily demanding, especially when only a few of the cylinders need fixing
- Multi-Piece Cylinder Head
These types of cylinder heads consist of a head for a group of two cylinders or more. They are usually used in multi-cylinder engine, particularly modular engine types. Multiple piece cylinder heads make servicing engine cylinders easy, since only the required head is removed.
The disadvantage of multiple cylinder head design is that the different pieces tend to move a lot, causing a rapid wear of the engine block decks. They are also not as simple as the single cylinder heads to manufacture.
Vehicles use different types of cylinder heads to seal the engine block. The type on your car engine depends on the engine configuration and car model. It’s also possible to install your preferred cylinder head type, based on the expected performance and durability. Regardless of head type, problems will often come up to make the assembly fail. Move on to the next section for a detailed description of common issues and their signs.