Open Deck vs. Closed Deck: Which is Right for You?

You might wonder what the difference is between an open deck and a closed deck engine block. 

There are three different types of engine blocks: open, semi-open, and closed. Each type has its own unique benefits and drawbacks. 

This article will compare the most common open deck vs. closed deck and explore their similarities and differences. 

Table of Contents

• What is an open deck?
  • Pros of Open deck
  • Cons of Open Deck
• What is a closed deck?
  • Pros of Closed Deck
  • Cons of Closed Deck
• Open deck vs. closed deck – Difference
• Closed deck conversion
• FAQs

What is an open deck?

An open deck engine is a type of internal combustion engine where the cylinder walls are empty at the bottom, and there is no roof over the cylinders.

The open deck layout features a channel that is open all the way through from the cylinders to the engine block. Most aluminum blocks with low horsepower use this type of engine.

The main advantage of an open deck design is that it helps to improve cooling by allowing better airflow around the cylinders. Additionally, it can also reduce costs by simplifying the manufacturing process.

However, one downside of an open deck engine is that it may be more susceptible to leaks and other problems.

As a result, it is essential to carefully consider all the pros and cons before choosing this engine for your vehicle.

Pros of Open deck

• It has better cooling performance due to an open cooling channel between the cylinder and the block. 
• It has complete coolant contact with the upper portion of the cylinder.
• Due to the use of less material, manufacturing costs are lower.
• It is easier to make because it has fewer parts and takes less time.

Cons of Open Deck

• Low support to the cylinders at the highest pressure point throughout the stroke.
• When the engine is pushed hard to make more power, the cylinder walls may crack, or the cylinder shape may change.
• You can’t tune the engine, use high compression, or add a turbo to make it much more powerful than stock.
• Open deck engines were not used much in the past because they were weak, and the walls of the cylinders would break. But now, it is used more in modern high-performance engines. This is because new technologies have made it easier to create a design that works better.

What is a closed deck?

A closed deck is a type of engine block design. As the name suggests, the engine block deck’s design is almost like a closed deck, with very little space between the cylinders and the block.

It is called a “closed configuration,” but there are some open spaces for coolant passage and head fasteners. 

The engine block is integrated with the tops of the cylinders. Most of the time, this kind of engine is used in blocks made of cast iron.

The closed deck construction helps to increase rigidity and strength in the engine, which can help to improve performance. Additionally, closed deck designs can also help to prevent cylinder liner blow-out.

Pros of Closed Deck

• Better support for the cylinder heads when the engine is under heavy load.
• Unlimited tuning and exceedingly high power output in comparison to stock.

Cons of Closed Deck

• There is less space for coolant to flow around the cylinder, which makes the engine less efficient.
• It costs more than having an open deck.
• It requires more precise drilling around the deck, increasing manufacturing time.

Most vehicles used a closed deck engine more in the past because higher power limits are guaranteed and improved cylinder wall strength.

Open deck vs. closed deck – Difference

There are a lot of differences between open deck vs. closed deck engine blocks. Let’s compare both in brief. 

• The main difference between open and closed deck engine blocks is the design. The open deck layout has channels between the cylinder and the engine block. And the closed deck has only a few spaces between the cylinder and the engine block. 
• Open decks are widely used in aluminum blocks with low horsepower. Closed decks are commonly used in blocks made of cast iron.  
• The cost of Open deck engine blocks is lower than the price of Closed deck. 
• The manufacturing cost and time are also less in open deck engine blocks because it uses fewer materials and effort. But, it takes more time and cost to make closed decks. 
• Closed deck engines support the engine when vehicles carry a heavy load. But, Open decks don’t keep that.
• Coolant functions of Open deck engine blocks work better than closed decks because closed decks have fewer spaces for circulating.
•  Closed-deck engines offer Unlimited tuning and exceedingly high power outputs, but you can’t tune open-deck engines. 

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Closed deck conversion

So, the next question is, “Can an open-deck block be turned into a closed-deck block for more strength?” Again, the answer is “Yes.” Most of the time, putting a plate between the cylinder and block walls is all it takes to turn an open deck into a closed one.

This plate will have holes, just like a closed deck, so the coolant can flow through it.

Most of the time, the insert is pressed in, so it doesn’t move around. If it did, it would defeat the purpose of reinforcing those areas.

If you want to know which one is better, the answer depends on what you want your engine to do. For example, suppose you’re building a crazy high-horsepower monster. In that case, a closed deck block might give you the extra strength you need, but some engines always require additional power.

Since it was first introduced many years ago, open deck blocks have advanced significantly. Some can now withstand high power levels without breaking. But, again, it’s crucial to remember that your engine could malfunction at various other places due to increased power; the deck isn’t always the problem.

There are many differences between open deck vs. closed deck engine blocks. And those have different functions. The manufacturing cost of an open deck is lower than a closed deck. But closed deck engines are more powerful than open deck blocks. So then, you can change your open deck block to a closed deck to gain more power for your engine. 

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FAQs