Want to get electricity at low cost? Reliability will be your problem. Want it to have powerful functions and reliability? This will hit your wallet more severely...or is it? Enter the world of block conversion.

When it comes to Subaru engines, even considering their weaknesses and some inherent design flaws, they are still and will always be legendary Japanese tuning platforms. These engines can easily provide power, are well known and available, and are excellent choices for many performance-oriented applications, but at a price.

In today's world of cheap horsepower, with the help of power adders such as nitric oxide, turbochargers and blowers, car enthusiasts are getting more and more likely to get some serious horsepower numbers. In fact, 500, 600, or even 700 horsepower has almost become the norm in the street car industry, let alone the racing industry. With all these affordable power sources becoming easily available, reliability is another part of the equation that is often overlooked.

Considering the choice of power, price, and reliability, you can usually get two-thirds of it in the past few years. Want to get electricity at low cost? Reliability will be your problem. Want it to have powerful functions and reliability? This will hit your wallet more severely...or is it? Enter the world of block conversion-also known as block filling.

Filling blocks with concrete or epoxy block fillers is a cheap alternative to weekend racers because it works. However, because they are filled with some hard and tough substances, the coolant capacity is small, so they sacrifice some driving performance. On the other hand, CNC closed platform block conversion provides a better solution.

Let’s dive into all the reasons why you should consider a closed platform switch instead of an open platform.

First of all, the open deck is very weak-simple and straightforward. Yes, they provide that all cylinders are completely surrounded by coolant to reduce heat, but this open deck cylinder block is unsupported and often moves, leaks at the cylinder head gasket, or worse, breaks-to you Leave any number of serious engine problems. What do you do to prevent these problems? 

You will get CNC closed platform block conversion. Most of the time, customers are building Subaru engines for street car, drag racing or road racing applications. If the customer wants to get a lot of power, Nemesis Performance solves the inherent weakness of the cylinder block structure. 

We put it on our Haas CNC, and we actually machined the so-called closed platform blocks. Basically, the cylinders and the things that support them in the block are held together by only four small tags. As the boost pressure increases and horsepower increases, and the harmonics that accompany the horsepower increase, they actually rupture the cylinder liner. The block now needs to be repaired and sleeves are needed. 

We adopted the concept of scanning the block to CAD. We designed these processed blades. The cylinder block is machined, the insert is pressed into and effectively closes the upper layer of the cylinder block, and supports the cylinder structure where needed, which is usually where all the combustion force occurs in the first half inch of the cylinder block.

To create a closed platform block conversion, the block is installed and dialed into the CNC machine and cut around the cylinder and water jacket, leaving a register (wall shelf) that is usually 0.500˝ deep. After cutting the block, the back (plug) is also cut from solid aluminum. Today's CNC is accurate to one thousandth of an inch, which makes this job easy.

After being completely cleaned and ready, press the insert/plug into the upper part of the block until they rest against the register. This will prevent the insert from falling further into the block. After the insert is installed, the block will undergo further processing, such as processing the coolant port on the deck, decorative mating surfaces, and drilling and honing.

Now, what you are left with is a fully enclosed deck engine block, which offers many benefits than your previously weak open deck engine block. It not only creates a more powerful engine, but also significantly increases the clamping surface of the cylinder head gasket, which is another inherent problem of Subaru. You get the best of both worlds. You have more surface area to clamp the cylinder head gasket and maintain its integrity, while maintaining rigidity and supporting the cylinder from movement and cracking.

The structural rigidity and support due to the insert will also help solve the engine harmonics of the starter, but it also improves the engine's ability to increase cylinder pressure. The support depth of the billet is 0.500˝, which increases the strength of the upper part of the cylinder, where most of the cylinder pressure is achieved. This helps prevent the cylinder from walking, or worse, not round-also called an ellipse.

Although the open platform block provides good cooling aspects, cooling in the closed platform block is not a problem because the coolant flowing to the head still passes through a small kitchen that matches the port hole in the head gasket. This is the previous limitation of coolant flow. The billet support also helps to take heat away from the upper part of the cylinder.

Next, we significantly increased the clamping surface area on the upper deck of the engine, which is very suitable for places where there is no support material in the cylinder coolant cavity. The increase in the clamping surface area is a major improvement in maintaining the integrity of the cylinder head gasket. More cylinder pressure equals more power, and now this engine block is ready for both.

If the customer wants to travel northward for 500 horsepower or more than 30 pounds. For the booster, an enclosed deck block is a necessary condition for additional protection. This is not to say that you can't do it without this modification, but you really push the limits of everything in the engine at that level. The upgrades we see at these horsepower levels are oil injection, hypereutectic pistons instead of forging and the deck structure of the block itself.

Next time you think about power, price, and reliability, remember that you can have everything.

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