What Is a Subaru Short Block? A Complete Guide

For many Subaru enthusiasts, especially those with the legendary EJ series, there’s a common fear: catastrophic engine failure. Head gasket issues and ringland failure are well-known weak points that can end the fun abruptly. While the factory engine is great for stock power, it simply wasn’t built to handle the demands of high-performance tuning. The solution isn’t just about adding power; it’s about building reliability from the ground up. A performance Subaru short block replaces those weak links with forged components, giving you the peace of mind to push your car without worrying about what might break next.

Key Takeaways

• Build a Stronger Engine Core: A performance short block replaces your engine's stock internals with stronger, forged components. This provides the durable foundation needed to reliably handle horsepower levels that would otherwise risk catastrophic failure.
• Match the Block to Your Build: Your horsepower goals and driving style (daily, track, or off-road) determine which short block is right for you. Defining your purpose first ensures you invest in a block that meets your performance needs without overspending.
• Budget for the Complete Project: A short block is not a drop-in part; it requires other critical upgrades. Be sure to factor in costs for an improved cooling system, a larger fuel system, professional installation, and a custom engine tune to ensure your new engine runs safely and performs correctly.

What Is a Subaru Short Block?

If you’ve spent any time in the Subaru performance world, you’ve probably heard the term “short block.” So, what is it? Think of the short block as the foundation of your engine. It’s the entire bottom half, housing the critical rotating assembly that generates power. When your stock engine reaches its limits or fails, a performance short block is often the starting point for a stronger, more reliable build. It provides a solid base that allows you to push for higher horsepower and torque, whether you're building a daily driver, a track weapon, or a capable overlander.

Understanding what a short block is, and what it isn’t, is the first step in planning your engine build. It’s not a complete, drop-in engine, but rather a core component that gives you the flexibility to create a setup tailored to your specific goals.

The Core Components

A Subaru short block is the assembly of the lower portion of your engine. It includes the engine case itself, which is the main structure, along with the internal parts that do the heavy lifting. Inside, you'll find the crankshaft, which converts the up-and-down motion of the pistons into the rotation that turns your wheels. The pistons are connected to the crankshaft by connecting rods. Finally, a series of bearings ensures everything spins smoothly with minimal friction. These core performance parts form the heart of your engine, and their quality determines its strength and power potential.

Short Block vs. Long Block: What's the Difference?

The easiest way to understand the difference is to think of a short block as just the bottom half of the engine. A long block, on the other hand, is more complete. It includes the short block plus the top-end components: the cylinder heads and the valvetrain (camshafts, valves, and springs). Choosing between them depends entirely on your build. If your cylinder heads are in great shape, you might opt for a short block and transfer your existing top-end parts. If you're starting fresh or your heads are damaged, a long block can be a more straightforward solution. This decision often comes down to your budget, horsepower goals, and what a professional recommends after an inspection and discussion about your engine tuning services plan.

Debunking Common Short Block Myths

One common myth is that installing a short block is a simple plug-and-play affair. In reality, it requires significant labor and expertise. Since it’s only the bottom half of the engine, you or your mechanic will need to source, inspect, and properly install the cylinder heads and valvetrain. This is a critical step, as mixing old or worn components with a brand-new short block can create compatibility issues. For example, warped cylinder heads can lead to head gasket failure, undoing all your hard work. Ensuring every component is matched and installed correctly is key to building a reliable engine, which is why many enthusiasts turn to complete Subaru WRX upgrade packages to guarantee compatibility.

Why Your Stock Short Block Has Its Limits

Your Subaru’s factory engine is a well-engineered machine, designed to provide years of reliable daily driving. It’s built to meet specific performance, emissions, and cost targets for a mass market. However, when you start chasing higher horsepower for the track or demanding more torque for overlanding, you’ll quickly find the boundaries of those factory specifications. The stock short block, which forms the foundation of your engine, simply wasn't designed for the extreme stress that comes with significant power increases.

This isn't a knock against Subaru's engineering; it's a matter of purpose. The components inside a stock engine are chosen for a balance of performance and longevity under normal conditions. Pushing your engine with a bigger turbo, aggressive tuning, or heavy-duty use exposes the inherent weak points in the factory internals and overall block design. Understanding these limitations is the first step in building a powerful and reliable engine that can handle whatever you throw at it. For enthusiasts, this means moving beyond factory parts and investing in components built specifically for performance.

Identifying Weak Points in Factory Internals

When you start adding power, the factory internals are the first components to show signs of strain. In many popular EJ-series engines, found in models like the Subaru WRX and STI from 2002 to 2014, the head gaskets are a well-known weak point. As you increase cylinder pressure with more power, the stock gaskets can fail, sometimes leading to coolant and oil mixing, which can cause major engine damage. This issue often appears as vehicles approach and exceed 100,000 miles, even on stock power. Beyond head gaskets, the factory cast pistons and connecting rods are not equipped to handle the intense heat and force generated by a high-output build, making them susceptible to failure under pressure.

How Much Power Can a Stock Block Really Handle?

This is one of the most common questions we hear, and the answer depends on your engine series. As a general rule, a stock EJ short block can reliably handle up to about 400 wheel horsepower (WHP). For the newer FA series engines, found in models from 2015 to the present, that number is closer to 300 WHP. Pushing past these figures on factory internals is a serious risk. While some engines might hold together for a while, it’s not a question of if they will fail, but when. Proper engine tuning services are critical for maximizing power safely within these limits, but exceeding them without upgrading your short block is asking for catastrophic failure.

Open Deck vs. Closed Deck: Why It's Critical for Reliability

The design of the engine block itself plays a huge role in its strength. Most Subaru engines use an "open-deck" design, where the tops of the cylinder walls are unsupported. This design is efficient for cooling and cost-effective for manufacturing, making it ideal for a daily driver. However, under the high cylinder pressures of a performance build, those unsupported cylinder walls can flex or "walk." This movement can compromise the head gasket seal, leading to failure and other serious issues. A "closed-deck" block solves this by adding structural support around the tops of the cylinders. This reinforcement makes the entire assembly much more rigid, preventing flex and ensuring your engine remains reliable even at high power levels.

The Benefits of a Performance Short Block Upgrade

Upgrading your Subaru’s short block is one of the most significant steps you can take toward building a powerful and reliable engine. While the stock block is fine for daily driving, it becomes a liability when you start chasing higher horsepower. A performance short block replaces the factory-limited components with a foundation built to handle serious stress, giving you the confidence to push your car on the track, trail, or street. This upgrade isn't just about adding power; it's about building a smarter, stronger engine from the ground up.

Gain Power and Durability with Forged Internals

One of the biggest advantages of a performance short block is the inclusion of forged internals. Unlike the cast pistons and connecting rods found in stock engines, forged components are created under immense pressure, resulting in a much denser and stronger molecular structure. This strength is exactly what you need to handle the increased cylinder pressures from higher turbo pressure and more aggressive tuning. A built short block allows you to create a tailored setup, matching the bottom end to your specific cylinder heads, camshafts, and other performance parts. This means you can build an engine that not only produces more power but does so reliably, without the constant worry of catastrophic failure.

Improve Reliability with a Closed Deck Design

For Subaru owners, especially those with the EJ series engine, the open-deck design of the factory block is a known weak point. Under high cylinder pressures, the unsupported cylinder walls can flex or even crack. A performance short block often features a closed deck conversion, which reinforces the cylinder walls by adding metal supports that bridge the gap between the walls and the deck surface. This modification dramatically increases the block's rigidity, providing a stable platform for extreme power and improving head gasket sealing. This added reliability is crucial for anyone building a high-performance engine for the track or aggressive street use, as it helps prevent some of the most common and costly engine failures.

Keep and Upgrade Your Top-End Components

Choosing a short block upgrade gives you incredible flexibility. Since a short block is just the bottom half of the engine (the block, crank, rods, and pistons), you have the freedom to reuse your existing cylinder heads and valvetrain. This is a fantastic option if your top-end components are still in great shape. It also allows you to plan your build in stages, focusing your budget on a bulletproof bottom end now and saving a cylinder head upgrade for later. This approach gives you full control over your build, letting you mix and match components to perfectly suit your performance goals and budget for your Subaru WRX or STI.

Is It More Cost-Effective Than a Full Engine Swap?

While the initial investment might seem high, a performance short block can be a more cost-effective solution in the long run compared to a full engine swap or replacing a blown stock motor. By choosing a short block, you gain more control over the build, especially when reusing or upgrading your existing cylinder heads and other top-end parts. This flexibility can lead to significant savings. More importantly, you're investing in a foundation that is built to last and can handle future upgrades. Instead of paying for another stock engine that has the same inherent weaknesses, you're putting your money toward a durable solution that supports your long-term horsepower goals.

EJ vs. FA: Which Engine Platform Do You Have?

Before you can plan your build, you need to know exactly what you’re working with. Subaru’s two modern engine families, the EJ and the FA, have distinct characteristics, strengths, and weaknesses. Identifying which one is under your hood is the first and most important step in choosing the right performance parts for your car.

Understanding the EJ Series (2002–2014)

If you drive a WRX or STI from 2002 to 2014, you have an EJ series engine. This platform, including the EJ20, EJ25, and EJ257, is a legend in the tuning community for a reason. It’s known for its raw, connected feel and has massive aftermarket support, making it a favorite for enthusiasts who want to build serious power. While these engines are tough, older models can develop head gasket issues after about 120,000 miles. On its own, a stock EJ short block can generally handle up to 400 wheel horsepower (WHP), giving you a solid foundation for your Subaru STI upgrades.

Understanding the FA Series (2015–Present)

Starting in 2015, Subaru introduced the FA series engine in models like the WRX, BRZ, and Forester. The FA20DIT and FA24F engines use modern direct injection technology, which improves fuel efficiency and provides a smoother powerband right from the factory. While they are more refined, some early FA engines were known for oil consumption issues related to the piston rings. In stock form, the FA short block is a bit more limited than its predecessor and can reliably handle around 300 WHP. This makes a built short block one of the first essential performance parts for anyone chasing higher horsepower goals.

Why Engine Compatibility Is Crucial

Choosing a short block isn’t like picking parts off a shelf; compatibility is everything. A short block upgrade gives you incredible control over your build, allowing you to reuse or upgrade your cylinder heads and other top-end components. However, you must ensure the block you choose is designed for your specific Subaru model and year. Getting this wrong can lead to installation nightmares and serious performance issues. Verifying fitment from the start saves you time and money, and ensures your new setup works seamlessly with professional engine tuning services to finalize the build.

What Are Your Performance Short Block Options?

Once you’ve decided to upgrade, the next step is figuring out which type of short block is right for your Subaru. The market offers several options, each designed for different goals, from simple replacements to full-blown race builds. Understanding these choices is key to building an engine that not only performs how you want but also holds together when you put your foot down. Let’s walk through the main types of short blocks you’ll encounter.

OEM Stock Replacements

An OEM (Original Equipment Manufacturer) short block is a direct, factory-spec replacement for your engine's bottom end. It’s built by Subaru and contains the same components as the block that came in your car from the dealership: the case, crankshaft, connecting rods, and pistons. This is the most straightforward option if your goal is simply to replace a failed or worn-out block without aiming for higher horsepower. While it’s a reliable choice for a stock vehicle, it carries the same limitations as your original engine and isn’t designed to handle significant power increases.

Forged and Built Short Blocks

This is where true performance begins. A forged, or built, short block replaces the stock cast components with much stronger forged parts. Forged pistons and connecting rods can withstand far more heat, pressure, and stress than their OEM counterparts, making them essential for any build involving a larger turbo, aggressive tuning, or high-revving applications. These blocks are the foundation for creating a powerful and reliable engine, allowing you to tailor the bottom end to match your specific cylinder heads, camshafts, and other performance parts. They provide the durability needed to push your Subaru well beyond its factory limits.

Stroker Short Blocks

If you’re chasing maximum torque and horsepower, a stroker short block is an excellent solution. This type of build modifies the engine's geometry by using a crankshaft with a longer stroke. This increase in stroke length effectively enlarges your engine's displacement, for example, turning a 2.5L into a 2.7L. The result is a significant bump in torque across the entire powerband, which can make a dramatic difference in acceleration and overall performance. Stroker kits are a more advanced upgrade, often reserved for serious track or competition builds where every bit of power matters.

Understanding Performance Stages

As you shop for built blocks, you’ll often see them advertised in "stages" (e.g., Stage 1, 2, 3) or rated for specific horsepower goals like 550 BHP or 750 BHP. These stages are a builder’s shorthand for communicating a block's power-handling capability. A lower-stage block might include forged pistons and rods suitable for a spirited daily driver, while a higher-stage block will feature more robust components like billet crankshafts and upgraded bearings. These ratings help you match a short block to your power goals and ensure your investment is properly aligned with the necessary engine tuning services.

What's Included (and What Isn't)

It’s crucial to know exactly what you’re buying. A short block is the bottom half of your engine. It consists of the engine case (block), crankshaft, connecting rods, and pistons, all pre-assembled. What it doesn't include is the top end: the cylinder heads, camshafts, and valvetrain. This is distinct from a "long block," which is a more complete assembly that includes both the top and bottom halves. The advantage of buying a short block is that you can reuse your existing cylinder heads or upgrade them separately, giving you more control over your Subaru WRX upgrades and overall build.

Budgeting for a Performance Short Block

Understanding the costs involved in a short block upgrade is key to planning your build. The price can vary significantly depending on your horsepower goals and whether you stick with factory parts or opt for a high-performance build. Let's break down the numbers so you can create a realistic budget and get the most out of your investment.

The Cost of an OEM Short Block

If your goal is simply to get your Subaru back on the road with factory performance, an OEM short block is a dependable option. A brand-new OEM short block typically costs between $1,600 and $1,800. This route restores your engine to its original specifications, making it a straightforward replacement for a damaged or worn-out unit. While it’s a solid choice for reliability, it doesn’t include the stronger components needed to handle significant power increases. Think of it as hitting the reset button, not adding a new level to your build.

The Cost of a Performance Short Block

This is where things get exciting. A built short block with stronger, forged internals is essential for anyone looking to make serious power. These performance-focused blocks start around $3,000 and can range up to $18,000 or more, depending on the build's complexity and power rating. This price jump accounts for the superior materials and precision engineering required to handle the stress of higher horsepower and torque. Forged components provide the durability needed for everything from spirited daily driving to competitive track days, making them a necessary investment for your Subaru WRX upgrades.

Factoring in Labor and Installation

The price of the short block itself is only part of the total cost. Professional installation is crucial for protecting your new engine, and this typically runs between $1,500 and $3,000. This isn't a corner you want to cut; a proper installation by experienced technicians ensures everything is assembled, torqued, and sealed correctly. After the install, a professional tune is also non-negotiable. Proper engine tuning services will calibrate your ECU to the new components, ensuring your engine runs safely and efficiently while maximizing its new potential.

What Drives the Price Difference?

You might wonder why there's such a vast price range for performance short blocks. The answer comes down to materials, craftsmanship, and horsepower targets. A block built to handle 400 horsepower uses different components than one designed for 800 horsepower. The higher the power goal, the stronger and more expensive the materials need to be. Forged pistons, connecting rods, and crankshafts cost more than their cast counterparts but are essential for durability under pressure. The price also reflects the intensive labor and precise machining required to assemble a reliable, high-output engine from a collection of performance parts.

How to Choose the Right Short Block for Your Build

Selecting the right short block is the most important decision you'll make for your engine build. It’s the foundation that determines your car's potential for power, reliability, and longevity. Choosing incorrectly can lead to a frustrating cycle of repairs and wasted money, while the right choice sets you up for success from day one. Before you even think about a turbo or exhaust, you need a clear plan for your engine's core.

The ideal short block depends entirely on how you plan to use your Subaru. Are you building a reliable daily driver with a little extra spirit? A high-strung track weapon that lives at redline? Or a rugged overlander built to conquer the wilderness? Each of these goals demands a different approach and a different type of short block. By defining your purpose first, you can invest in a foundation that perfectly matches your ambitions and avoid paying for capabilities you don't need or, worse, ending up with a block that can't handle your goals.

First, Define Your Horsepower Goals

Before you spend a single dollar, you need to answer one question: how much horsepower do you really want? This number will guide every other decision in your build. A stock EJ short block can generally handle up to 400 wheel horsepower (WHP), while a stock FA block is safe up to about 300 WHP. Pushing past these thresholds on factory internals is a gamble, and it often ends with catastrophic engine failure.

Being honest about your power goals from the start is crucial. If you know you want to build a 500 WHP street monster, you can immediately rule out a stock block and focus on built options. This clarity saves you time and prevents you from buying parts that won't support your final vision.

Choosing a Block for a Daily Driver

If your goal is a fun, reliable car for your daily commute and spirited weekend drives, you don't necessarily need a fully built, race-spec engine. For moderate power goals, a genuine OEM short block often provides the perfect balance of performance and factory-proven reliability. It’s designed to run just like your Subaru did when it left the showroom, giving you peace of mind for tens of thousands of miles.

This path is ideal for owners who want to enhance their driving experience without sacrificing dependability. You can still add supporting performance parts to sharpen throttle response and add a bit of power, but the factory-spec core keeps the build straightforward and cost-effective. It’s the smart choice for a practical yet exciting daily machine.

Choosing a Block for the Track

When your Subaru is destined for the track, the rules change completely. The constant high RPMs, extreme heat, and sustained stress of racing will quickly find the weak points in a stock engine. This is where a built short block becomes essential. These engines are specifically engineered for competition and feature forged internals like pistons and connecting rods that can withstand immense pressure.

Built short blocks are often rated in stages for specific horsepower targets, such as 550, 750, or even 1,100+ horsepower. Each stage includes increasingly robust components and precision engineering to handle the abuse. For anyone serious about track days or competitive racing, investing in a built block for your Subaru STI or WRX isn't just an upgrade; it's a requirement for survival.

Choosing a Block for Off-Road & Overlanding

Off-road and overlanding builds present a unique set of challenges. While you might not be chasing peak horsepower, you need unwavering reliability and low-end torque for climbing steep grades or navigating technical terrain. For high-power builds or those running significant boost, a closed deck block is the superior choice. This design adds crucial support to the cylinder walls, drastically reducing the risk of flex and preventing common issues like head gasket failure under heavy load.

This structural reinforcement is critical for the long-term durability demanded by overlanding solutions. Whether you're deep in the backcountry or towing gear for a weekend adventure, a closed deck block provides the strength and confidence you need to push your Crosstrek or Forester further.

What to Look for in a Short Block Builder

Choosing a short block is a big step, but choosing the right builder is just as critical. The builder is the expert who assembles the heart of your engine. Their experience, attention to detail, and quality control directly impact your Subaru's performance and longevity. A great builder doesn't just sell you a part; they provide a reliable foundation for your entire build. When you're comparing options, it's easy to get lost in specs and prices. Instead, focus on these three key areas to find a partner you can trust with your project.

Build Quality and Warranty

The reliability of a built engine comes down to more than just the components inside it. A well-built engine with the right performance parts can handle significant power reliably, but only if it's assembled with precision. It’s about matching parts to your goals, expert assembly, and good tuning.

A reputable builder will stand behind their work with a clear warranty. This isn't just a piece of paper; it's a statement of confidence in their product and assembly process. Look for a builder that offers a warranty on their short blocks. For example, a 12-month/12,000-mile warranty shows that the builder has tested their products and is committed to quality, giving you peace of mind on the road or track.

Guaranteed Model and Year Compatibility

The Subaru world is full of variations, and what works for a 2008 STI won't fit a 2022 WRX. This is why guaranteed compatibility is non-negotiable. Always check that the short block is designed specifically for your Subaru's model and year. A professional builder will have clear fitment information and can answer any questions you have about your specific vehicle.

This removes the risk of ordering an expensive part that doesn't work with your existing components. Whether you're looking for Subaru WRX upgrades or parts for your Forester, the builder should ensure a perfect match. This precision guarantees that the installation process goes smoothly and the engine performs as expected.

Tuning Needs and Future Upgrade Paths

Installing a performance short block is not the final step. To get the most out of your new engine safely and effectively, a professional tune is essential. Your builder should be able to discuss what your tuning requirements will be. They can often recommend experienced tuners or provide base maps to get you started. This conversation ensures your new engine runs safely and efficiently from day one.

Think about your long-term goals as well. A good builder can help you choose a short block that not only meets your current needs but also leaves room for future upgrades. If you think you might want more power later, discuss this upfront. They can guide you toward a block with a stronger foundation, like a closed deck case, that can support your ambitions as they grow. This foresight saves you from having to start over down the line. You can also ask about their own engine tuning services to keep the process streamlined.

Don't Forget These Supporting Upgrades

Installing a performance short block is a major step, but it doesn't work in isolation. To get the reliable power you’re investing in, you need to make sure the rest of your car can keep up. Think of it like a team: your new short block is the star player, but it can't win the game without a strong supporting cast. Neglecting these critical areas can lead to poor performance, or worse, catastrophic engine failure. Before you finalize your budget, make sure you account for these essential supporting upgrades. They aren't just recommended; they're required for a successful and durable build.

Upgrade Your Cooling System

More power generates more heat. It’s a fundamental rule of engine performance. Your stock cooling system was designed for stock power levels, and it will quickly become overwhelmed when trying to manage the thermal load of a built engine. An overheating engine is a recipe for disaster, leading to warped heads, damaged pistons, and other expensive problems. To protect your investment, you must upgrade your cooling system. This typically includes a high-performance aluminum radiator and an external oil cooler. These performance parts are designed to dissipate heat far more efficiently than their factory counterparts, ensuring your engine stays at a safe operating temperature whether you're on the track or stuck in traffic.

Upgrade Your Fuel System

Just as more power creates more heat, it also demands more fuel. Your factory fuel pump and injectors are calibrated to deliver a specific amount of fuel for the stock engine's needs. When you install a performance short block capable of making significantly more horsepower, the stock fuel system simply can't supply enough fuel to keep up. Running a lean air-fuel mixture because of an inadequate fuel system is one of the fastest ways to destroy a new engine. You'll need to install an upgraded fuel pump and larger fuel injectors to provide the necessary volume. This ensures your engine gets the fuel it needs to make power safely and reliably across the entire RPM range. You can find these components in our Subaru WRX upgrades collection.

Get a Professional Install and Tune

This is not the place to cut corners. While it might be tempting to save money with a DIY installation, a professional install is critical for the long-term health of your engine. Experienced technicians have the tools and knowledge to handle the job correctly, ensuring everything is assembled to precise specifications. After the installation, a professional tune is absolutely mandatory. A tune adjusts your engine's computer to account for all the new hardware. Without it, your car won't run properly and you risk severe damage. Our expert engine tuning services ensure your new setup is perfectly calibrated for maximum power and reliability. Expect to budget for both the installation and the custom tune to complete your build the right way.

Related Articles

• Subaru Short Block 101: A Complete Guide
• Subaru Engine Power Block: Your Ultimate Upgrade Guide

Frequently Asked Questions

When should I actually consider a built short block instead of just replacing my stock one? You should think about a built short block the moment your horsepower goals exceed what the factory engine can safely handle, which is around 300 wheel horsepower for the FA series and 400 for the EJ series. If you just need to replace a failed engine and plan to keep the car stock, an OEM replacement is a perfectly fine choice. However, if you intend to add a larger turbo or pursue any significant power gains, a built block with forged internals is the only way to do it reliably. It's an investment in a foundation that can support your ambitions.

What other costs should I budget for besides the short block itself? The short block is the centerpiece, but it's not the whole picture. You must factor in the cost of a professional installation and a custom engine tune; these are not optional. Your new engine will also require an upgraded cooling system to manage the extra heat and an upgraded fuel system to supply enough fuel. Planning for these supporting modifications from the start is essential for protecting your investment and ensuring your new engine runs safely and performs as expected.

Do I really need a closed deck block? For many builds, you don't. If you're creating a spirited daily driver with moderate power increases, a quality open deck block will serve you well. A closed deck block becomes necessary when you are building a high-horsepower engine for the track or a high-load application like a serious off-road vehicle. The added reinforcement prevents cylinder wall flex under extreme pressure, which is critical for protecting the head gasket and ensuring engine longevity in the most demanding situations.

I see short blocks rated for different horsepower levels. How do I choose the right one without overspending? The key is to be realistic about your ultimate power goal and add a small buffer for safety. If you know you want a 500 horsepower street car, buying a block rated for 550 horsepower is a smart move. This ensures the components are not constantly stressed at their absolute limit. There is no need to buy a block rated for 1,000 horsepower if you have no plans to build a car that powerful, as you would be paying for capability you will never use. Choose the block that aligns with your vision.

What is the most common mistake people make when upgrading their short block? The most frequent and costly mistake is cutting corners on the supporting systems. People spend thousands on a beautiful new short block but try to save money by reusing the stock radiator, fuel pump, or by skipping a professional tune. This approach almost always leads to failure. An engine is a complete system, and a powerful new short block will quickly overwhelm factory components. Investing in the proper cooling, fuel, installation, and tuning is not an upsell; it is a requirement for a successful build.