Katech 112mm Throttle Body

Bigger Isn't Automatically Better

Few modifications generate as much discussion, or as much misinformation, as throttle body upgrades. Spend a few minutes browsing Camaro forums or Facebook groups and you'll quickly find enthusiasts sharing completely different experiences. Some claim they picked up significant horsepower simply by installing a larger throttle body, while others report little or no measurable improvement. Both experiences can be correct.

The difference isn't the throttle body itself, it's the engine combination.

A throttle body doesn't create horsepower, compress air, or generate boost. Its purpose is much simpler: to regulate and deliver airflow into the supercharger while minimizing restriction. If the existing throttle body has become a bottleneck, increasing its airflow capacity can help the engine breathe more efficiently and support additional horsepower. However, if the factory throttle body is already capable of supplying all the air the engine demands, installing a larger unit often produces little more than a lighter wallet.

Understanding when a throttle body becomes a restriction, and when it doesn't, is the key to making an informed upgrade decision.

Understanding Airflow on the LT4

One of the biggest misconceptions surrounding throttle body upgrades is that they somehow "make horsepower." In reality, a throttle body is simply one component within a much larger airflow system. To understand when a throttle body upgrade is beneficial, it's important to first understand how air travels through an LT4 engine and why airflow efficiency, not simply boost pressure, is one of the primary factors that determines horsepower.

The supercharged 6.2L LT4 is essentially a large air pump. Every revolution of the crankshaft requires the engine to ingest a tremendous volume of air, compress it, cool it, and distribute it evenly to all eight cylinders. Every component between the air filter and the combustion chamber influences how efficiently that process occurs. If one component becomes restrictive, it affects everything downstream.

Unlike a naturally aspirated engine, which relies solely on atmospheric pressure and piston movement to fill the cylinders, the LT4 uses a positive displacement supercharger to actively force additional air into the engine. The factory Eaton TVS 1.7L supercharger, and popular aftermarket units such as the Magnuson 2650 and Whipple 3.0L, are designed to move significantly more air than the engine could ingest on its own. As horsepower goals increase, however, the supercharger can only be as effective as the components feeding it.

Every restriction in the intake system forces the supercharger to work harder to pull air through the inlet. That additional effort generates heat, increases parasitic loss, and ultimately reduces the system's overall efficiency. For this reason, experienced engine builders don't look at airflow as a collection of individual parts; they evaluate the entire induction system as one continuous path.

The journey begins at the air filter, where outside air enters the intake system. From there, it passes through the intake tube before reaching the throttle body. The throttle body regulates airflow into the supercharger and serves as one of the primary control points within the intake tract. Once the throttle blade opens, air enters the supercharger snout and rotor pack, where it is compressed before passing through the intercooler bricks to reduce charge-air temperature. The cooled, pressurized air is then distributed through the intake manifold, into the cylinder heads, past the intake valves, and finally into the combustion chambers.

Each component in this sequence has the potential to become a bottleneck. While enthusiasts often focus on the supercharger itself, the blower can only compress the amount of air it is capable of receiving. A restrictive intake, undersized throttle body, inefficient inlet casting, or poorly flowing cylinder heads can all limit the effectiveness of even the most capable supercharger.

A helpful way to visualize this is to imagine trying to fill a swimming pool using a garden hose. Increasing the size of the pump will certainly move more water, but if the hose remains the same diameter, it eventually becomes the limiting factor. Replacing only the hose while leaving every other restriction in place may improve flow slightly, but the greatest gains occur when the entire system is optimized to work together. The same principle applies to the LT4's induction system. Maximum performance is achieved not by installing the largest individual component, but by eliminating restrictions throughout the entire airflow path.

This is also why boost pressure can be misleading. Many enthusiasts assume that higher boost automatically equates to greater horsepower, but boost is simply a measurement of pressure within the intake manifold. Pressure often increases when airflow encounters resistance. In many cases, reducing a restriction allows the engine to consume a greater mass of air even though the boost gauge displays the same—or sometimes slightly lower—pressure. The engine is breathing more efficiently, the supercharger is working less to achieve the same result, and horsepower increases because the cylinders are receiving more oxygen, not because the boost number is higher.

This distinction between pressure and mass airflow is one of the most important concepts to understand when selecting a throttle body. A larger throttle body is not intended to create boost or magically produce horsepower. Its purpose is to reduce inlet restriction so the supercharger can operate more efficiently. Whether that reduction in restriction translates into additional horsepower depends entirely on the airflow demands of the engine combination.

As modifications are added, including ported superchargers, aftermarket snouts, larger positive displacement blowers, aggressive camshafts, improved cylinder heads, and higher engine speeds, the demand for airflow increases dramatically. Eventually, the factory throttle body may become one of the limiting factors within the induction system. Determining when that point has been reached is the key to selecting the correct throttle body, rather than simply purchasing the largest diameter available.

Think of the LT4 Like a Straw

Imagine trying to drink a thick milkshake through a tiny coffee stirrer. No matter how hard you suck, the narrow opening limits how much milkshake can pass through. Replace that coffee stirrer with a large smoothie straw, and suddenly the milkshake flows much more easily with the same amount of effort.

The LT4's induction system works in much the same way.

Every component between the air filter and the combustion chamber influences how easily air can reach the engine. If any one component becomes significantly more restrictive than the rest of the system, it acts like the narrow straw, limiting the amount of air the supercharger can ingest. The harder the supercharger has to work to overcome that restriction, the more energy it consumes, the more heat it generates, and the less efficiently it operates.

A throttle body is simply one section of that airflow path. When it is appropriately sized for the engine's airflow demands, air moves into the supercharger with minimal restriction. However, as airflow requirements increase through modifications such as a ported supercharger, larger positive-displacement blower, aftermarket camshaft, or improved cylinder heads, the factory throttle body can eventually become the equivalent of the coffee stirrer, it limits how efficiently the rest of the system can breathe.

The important takeaway is that replacing the throttle body alone doesn't guarantee additional horsepower. If another component immediately downstream, such as the supercharger inlet, rotor pack, intake manifold, or cylinder heads, remains the primary restriction, airflow will simply encounter the next bottleneck. Just as replacing only one section of plumbing doesn't dramatically increase water flow through an entire house, increasing the size of a single intake component doesn't automatically transform the performance of the entire induction system.

The highest-performing LT4 combinations aren't built by installing the largest individual parts available. They're built by eliminating restrictions throughout the entire airflow path so that every component complements the next. That's why experienced engine builders evaluate the induction system as a complete package rather than focusing on a single component in isolation.

Airflow Is More Important Than Boost

One of the most common misconceptions among performance enthusiasts is that boost pressure is a direct indicator of horsepower. It's an understandable assumption, after all, higher boost numbers are often associated with more powerful engines. However, while boost pressure is certainly an important tuning parameter, it is not the ultimate measure of engine performance.

Horsepower is produced by burning oxygen and fuel. The more oxygen an engine can efficiently ingest and combust, the more power it has the potential to produce. Boost pressure is simply one measurement of the resistance encountered as the supercharger forces air into the intake manifold. It tells you how much pressure exists within the system, but it doesn't necessarily tell you how much air is actually reaching the cylinders.

An easy way to understand this is to imagine placing your thumb over the end of a garden hose. As you partially block the opening, the pressure inside the hose increases. However, even though the pressure is higher, the total volume of water flowing through the hose decreases because you've created a restriction. Remove your thumb, and the pressure drops, but significantly more water is able to flow.

The same principle applies to an LT4's induction system.

When airflow encounters a restriction—whether it's an undersized throttle body, a restrictive supercharger inlet, or another bottleneck within the intake tract, the supercharger must work harder to force air through that restriction. As a result, manifold pressure often increases because air begins to accumulate ahead of the bottleneck. While the boost gauge displays a higher number, the engine may actually be receiving less usable airflow than a more efficient combination operating at slightly lower boost.

This is why experienced engine builders focus on mass airflow, not simply boost pressure. The goal is to maximize the amount of oxygen reaching the combustion chamber while minimizing the work required to get it there. A more efficient airflow path allows the supercharger to move a greater volume of air with less restriction, less heat generation, and reduced parasitic loss. In many cases, this translates into more horsepower even though the boost gauge shows the same, or occasionally even a slightly lower, pressure reading.

This concept becomes increasingly important as horsepower goals rise. Upgrades such as a high-flow intake, larger supercharger inlet, ported blower, properly sized throttle body, aftermarket cylinder heads, and optimized camshaft all work together to reduce restrictions throughout the intake system. Individually, each improvement may appear modest, but collectively they allow the engine to ingest substantially more air than it could with a restrictive induction system.

For this reason, it's important not to evaluate airflow upgrades based solely on whether they increase boost pressure. A throttle body upgrade that results in a one-pound reduction in boost isn't necessarily a step backward. If that reduction is accompanied by increased airflow, lower inlet restriction, improved supercharger efficiency, and additional horsepower, the engine is performing exactly as intended.

Ultimately, airflow, not boost, is what fills the cylinders with oxygen. Boost is simply the pressure created while attempting to move that air. Understanding the difference is one of the most valuable lessons an enthusiast can learn, because it changes the way every performance modification is evaluated. Instead of asking, "How much boost did I gain? "the better question becomes, "How much more air can my engine breathe?"

Griffin Motorsports Insight

It's not uncommon for customers to become concerned when they install a higher-flowing intake component and notice the boost gauge reads slightly lower than before. In many cases, that's actually a sign the engine is breathing more efficiently. By reducing inlet restriction, the supercharger no longer has to build as much pressure to move the same, or even a greater mass of air through the engine. That's why we place far more emphasis on horsepower, airflow, and overall engine efficiency than on boost numbers alone.

How Air Travels Through an LT4

Before deciding whether a larger throttle body is the right upgrade, it's helpful to understand exactly how air moves through an LT4 engine. Every molecule of air follows the same path from the atmosphere to the combustion chamber, and each component along that journey influences the engine's ability to produce horsepower.

The process begins at the air filter, where outside air is drawn into the intake system. Although often overlooked, the air filter and intake assembly establish the foundation for the entire induction system. A restrictive filter or undersized intake tube can limit airflow before it ever reaches the supercharger, forcing the engine to work harder to achieve its performance goals.

From the intake, air enters the throttle body. While its primary function is to regulate airflow based on accelerator pedal position, the throttle body also serves as one of the first potential restrictions within the induction system. As horsepower and airflow demand increase, the throttle body's diameter, blade design, and internal geometry all influence how easily air can enter the supercharger. When the throttle body becomes too restrictive for the engine's airflow requirements, it creates a pressure drop that reduces the efficiency of everything downstream.

After passing through the throttle body, air enters the supercharger inlet, commonly referred to as the snout. The inlet guides airflow into the rotor pack and plays a significant role in determining how efficiently the supercharger can ingest air. This is one reason many high-performance LT4 builds incorporate aftermarket or ported snouts. Improving the transition into the blower reduces turbulence and restriction, allowing the rotors to receive a smoother, more consistent supply of air.

Inside the supercharger, the rotor pack compresses the incoming air before forcing it through the intercooler bricks. Compression dramatically increases the air's temperature, and because hotter air is less dense, reducing that heat is critical to maintaining performance. The intercooler bricks extract heat from the compressed air before it enters the intake manifold, increasing air density and helping the engine produce consistent horsepower while reducing the likelihood of detonation.

From there, the cooled, pressurized air is distributed through the intake manifold and into the cylinder heads. The design of the intake runners, cylinder head ports, intake valves, and combustion chambers all influence how efficiently that air ultimately reaches each cylinder. Even the most capable supercharger cannot compensate for significant restrictions downstream. If the cylinder heads or camshaft cannot support the desired airflow, increasing the size of the throttle body alone is unlikely to produce substantial gains.

This illustrates one of the most important principles of engine performance: an induction system is only as efficient as its most restrictive component. Air must pass through every section of the intake tract before it reaches the combustion chamber. Improving one component while ignoring another simply shifts the bottleneck farther downstream.

Think of the intake system as a series of connected pipes. Increasing the diameter of one section may improve flow slightly, but if the remaining sections remain unchanged, the smallest restriction still determines how much air can ultimately reach the engine. True performance gains come from improving the entire airflow path rather than focusing on a single component in isolation.

For this reason, experienced engine builders rarely evaluate throttle bodies, supercharger snouts, ported blowers, or cylinder heads as independent upgrades. Instead, they view each component as part of a complete airflow package. The objective is to create a smooth, efficient path that allows the supercharger to move the greatest possible mass of air with the least amount of restriction.

Understanding this airflow path also explains why two seemingly similar LT4 combinations can respond very differently to the same throttle body upgrade. A stock Eaton-equipped Camaro ZL1 may see little benefit from a larger throttle body because the factory blower and inlet remain the primary restrictions. By comparison, a vehicle equipped with a Kong-ported supercharger, aftermarket snout, larger camshaft, and improved cylinder heads has significantly greater airflow demand. In that combination, the throttle body may become one of the final remaining restrictions, making an upgrade considerably more beneficial.

Rather than asking whether a larger throttle body "adds horsepower," the better question is whether it removes the next significant restriction in the airflow path. If the answer is yes, the upgrade has the potential to improve airflow, increase supercharger efficiency, and support additional horsepower. If the answer is no, your investment is often better directed toward the component that is actually limiting performance.

Every Restriction Adds Up

One of the most common mistakes enthusiasts make when modifying an LT4-powered vehicle is evaluating airflow upgrades one component at a time. It's easy to assume that replacing a single restrictive part will dramatically improve performance, but that's rarely how engine airflow works. In reality, every component between the air filter and the combustion chamber contributes to the engine's overall efficiency, and each restriction compounds the effects of the next.

Imagine driving on a four-lane freeway that suddenly narrows to a single lane because of road construction. It doesn't matter how wide or fast the freeway was before the bottleneck—traffic can only flow as quickly as the narrowest section allows. Widening one portion of the freeway while leaving the bottleneck untouched does little to improve the overall flow of traffic.

Air behaves much the same way.

The LT4's induction system is a continuous pathway, and air must pass through every component before it reaches the combustion chamber. If the throttle body flows significantly more air than the supercharger inlet can accept, the inlet simply becomes the next restriction. Likewise, if the blower is capable of moving more air than the cylinder heads can efficiently pass, airflow becomes limited at the cylinder heads rather than the throttle body. Every improvement shifts the bottleneck farther downstream until another component becomes the limiting factor.

This is why experienced engine builders rarely recommend upgrades based on a single horsepower number. Instead, they evaluate the entire combination. A stock Eaton-supercharged LT4 has very different airflow requirements than a Kong-ported blower, a Magnuson 2650, or a Whipple 3.0L. Each combination demands a different balance of components to achieve the greatest overall efficiency.

This systems-based approach is also why two vehicles producing similar horsepower may require different throttle bodies. One engine may have an efficient intake, a ported supercharger, aftermarket cylinder heads, and an aggressive camshaft, placing much greater demand on the throttle body. Another vehicle may achieve similar power through increased boost while retaining many factory airflow components, making the throttle body far less restrictive. Looking only at horsepower tells only part of the story; understanding the airflow path tells the rest.

Rather than chasing the largest individual components, the goal should always be to eliminate restrictions in a logical progression. Improving airflow where the engine is currently limited yields measurable gains. Replacing a component that is already capable of supporting your combination often produces little benefit because the true bottleneck remains elsewhere.

This philosophy is why the most successful LT4 builds are rarely defined by one standout component. Instead, they're the result of carefully matched parts that complement one another. A properly sized throttle body, efficient supercharger inlet, well-designed rotor pack, adequate intercooling, free-flowing cylinder heads, and an appropriately matched camshaft all work together to create an induction system that is greater than the sum of its individual parts.

Ultimately, the objective isn't to install the biggest throttle body, the largest supercharger, or the most aggressive cylinder heads. The objective is to create a balanced airflow package where every component supports the next. When restrictions are reduced throughout the entire intake tract, the supercharger operates more efficiently, inlet temperatures are better controlled, airflow increases, and the engine reaches its true performance potential.

When Does the Factory LT4 Throttle Body Become a Restriction?

One of the most common questions we receive at Griffin Motorsports is deceptively simple:

"How much horsepower will I gain from a larger throttle body?"

The honest answer is that there isn't a universal number.

Unlike modifications that directly increase an engine's airflow capacity, such as a larger supercharger, cylinder head improvements, or a more aggressive camshaft, a throttle body upgrade only becomes valuable once the factory unit can no longer supply the volume of air the engine demands. Until that point, replacing it with a larger unit often produces little measurable benefit because another component remains the limiting factor.

The challenge is determining when that point has been reached.

Rather than thinking in terms of horsepower alone, experienced engine builders evaluate airflow demand. Two LT4-powered vehicles producing similar power can require completely different throttle body sizes depending on the supercharger, engine speed, cylinder head flow, camshaft profile, and overall efficiency of the induction system.

Simply put, the more air your engine can consume, the more important the throttle body becomes.

The Factory LT4 Throttle Body Is Better Than Most People Think

One of the biggest misconceptions surrounding LT4 performance is that the factory throttle body is a major restriction on every supercharged engine.

In reality, General Motors did an excellent job designing the OEM electronic throttle body for the LT4 platform. Engineers had to create a component that provided precise throttle modulation, excellent idle quality, smooth drivability, long-term reliability, and enough airflow to support a 650-horsepower production engine under every conceivable operating condition.

For a stock Camaro ZL1, CTS-V, or C7 Z06, the factory throttle body is remarkably capable. Even many lightly modified combinations with a cold air intake, exhaust system, smaller pulley, or professional calibration continue to operate well within its airflow capacity.

This is why some owners install an oversized throttle body on an otherwise mild combination and report little or no improvement. The throttle body wasn't the bottleneck to begin with.

That doesn't mean larger throttle bodies don't work—it simply means the engine wasn't yet asking for more air than the factory unit could provide.

Griffin Motorsports Insight

One of the most valuable pieces of advice we can give enthusiasts is this: don't replace parts simply because they're popular. Replace them because they solve a limitation within your specific combination. The best-performing builds are planned around the engine's airflow requirements, not around internet trends.

Airflow Demand Increases with Every Modification

As performance modifications accumulate, the engine's appetite for air grows significantly.

Installing a smaller supercharger pulley increases rotor speed, allowing the blower to compress a greater volume of air. Porting the supercharger inlet and outlet reduces internal restrictions, enabling the blower to move that air more efficiently. Upgrading to a larger positive displacement supercharger such as a Magnuson 2650 or Whipple 3.0L increases airflow potential even further. Add a camshaft with greater valve lift and duration, free-flowing cylinder heads, and higher engine speeds, and the amount of air the engine is capable of consuming increases dramatically.

Eventually, one of the previously adequate components becomes the next restriction.

Depending on the combination, that restriction may be the throttle body.

The key point is that the throttle body doesn't become restrictive simply because horsepower increased. It becomes restrictive because the engine's airflow demand has finally exceeded the throttle body's ability to supply air efficiently.

Engine Speed Changes Everything

Another factor that is often overlooked is engine speed.

An LT4 operating at 4,500 RPM consumes significantly less air than the same engine operating at 6,800 RPM. As engine speed increases, each cylinder fills and empties more frequently, requiring the induction system to move an increasingly larger mass of air in a shorter amount of time.

This is one reason high-RPM combinations often benefit from airflow improvements that produce little change on lower-RPM street builds. The faster the engine turns, the greater the demand placed on every component within the intake tract.

It's not uncommon for a combination to perform perfectly at moderate engine speeds while beginning to show signs of airflow limitation near redline, where demand is at its highest.

Signs Your Combination May Benefit from a Larger Throttle Body

While there isn't a single horsepower threshold that automatically dictates when a throttle body should be upgraded, there are several indicators that suggest your combination may be approaching the limits of the factory unit.

Engines equipped with a ported Eaton supercharger, Kong-ported blower, Magnuson 2650, or Whipple supercharger often have substantially greater airflow demand than a stock LT4. Likewise, combinations featuring aftermarket camshafts, cylinder head upgrades, larger supercharger pulleys, or elevated engine speeds may begin to outgrow the airflow capacity of the factory throttle body.

At that point, increasing throttle body size may help reduce inlet restriction and allow the remainder of the induction system to perform more efficiently.

The important word is may.

Every combination should be evaluated as a complete system rather than assuming a larger throttle body is automatically required.

Why Bigger Isn't Always Better

Once enthusiasts accept that airflow restrictions exist, it's natural to assume that the largest available throttle body must therefore produce the best results.

Unfortunately, it's not that simple.

A throttle body should be selected the same way every other engine component is selected: by matching it to the requirements of the combination.

Installing a throttle body that is substantially larger than necessary does not automatically improve airflow, just as installing oversized fuel injectors doesn't automatically increase horsepower. Every component must work together.

A larger throttle body has the potential to reduce restriction, but only if the engine is actually capable of using the additional airflow. If another component becomes the bottleneck first, increasing throttle body size simply moves the restriction farther downstream while producing little measurable improvement.

This is why two nearly identical Camaro ZL1s can respond very differently to the exact same upgrade. One vehicle may have reached the airflow limits of the factory throttle body, while the other may still be limited by its supercharger inlet, cylinder heads, camshaft, or even the blower itself.

Choosing the correct throttle body is therefore not about buying the largest diameter available. It's about identifying the next meaningful restriction in your airflow system and selecting the component that complements the rest of the combination.

Choosing the Right Throttle Body for Your LT4

By now, it's clear that throttle body selection isn't simply a matter of choosing the largest diameter available. The correct throttle body is the one that complements your engine's airflow requirements, supports your horsepower goals, and integrates with the rest of your induction system. A properly matched throttle body can reduce inlet restriction, improve supercharger efficiency, and support future modifications without compromising drivability. Choosing one that's either too small or unnecessarily large often leaves performance on the table, or money wasted.

At Griffin Motorsports, we offer the complete Katech throttle body lineup because no two LT4 combinations are exactly alike. A stock Camaro ZL1 has very different airflow requirements than a Kong-ported blower or a Whipple-equipped race car. Rather than recommending the same product to every customer, we believe it's far more valuable to match the throttle body to the engine's current, and future, airflow demands.

The following recommendations are based on years of real-world experience working with LT4-powered Camaros, CTS-Vs, and Corvettes, and they represent the combinations we most commonly recommend to our customers.

Katech CNC Ported 95mm Throttle Body

For many LT4 owners, the best throttle body isn't a larger billet unit, it's an improved version of the factory throttle body.

The Katech CNC Ported 95mm begins life as a genuine GM throttle body before undergoing precision CNC machining to optimize the internal airflow path. Rather than dramatically increasing diameter, Katech focuses on improving the efficiency of the factory casting by removing unnecessary restrictions and reshaping the inlet and outlet geometry. The result is increased airflow while retaining the factory electronics, throttle mapping, idle quality, and drivability that made the original component so successful.

This makes the CNC Ported 95mm an excellent choice for enthusiasts who want to improve airflow without fundamentally changing the character of the vehicle. It delivers OEM refinement while providing additional airflow capacity for engines that have begun to outgrow the stock casting.

We frequently recommend the Katech CNC Ported 95mm for stock or lightly modified LT4 combinations, as well as vehicles equipped with a ported factory Eaton supercharger. It also pairs exceptionally well with mild camshaft upgrades, ported supercharger snouts, and other supporting airflow improvements that increase demand without requiring a substantially larger throttle body.

One of the greatest strengths of this throttle body is balance. It preserves the excellent manners expected from a street-driven Camaro while providing additional airflow headroom for enthusiasts who aren't yet building a maximum-effort combination.

Best Applications

• Stock LT4 engines looking for incremental airflow improvements

• Mild camshaft upgrades

• Street-focused builds emphasizing OEM drivability

• Customers planning future bolt-on modifications

Katech 103mm Billet Throttle Body

If there is a "sweet spot" within the LT4 aftermarket, the Katech 103mm Billet Throttle Body is it.

As airflow demand increases beyond what the factory casting can comfortably support, the 103mm billet unit provides a significant increase in airflow capacity without sacrificing the drivability expected from a premium street car. Precision-machined from billet aluminum and equipped with genuine GM electronics, it combines exceptional manufacturing quality with OEM-like throttle control and reliability.

This is the throttle body we recommend more frequently than any other because it aligns with the needs of the majority of serious LT4 enthusiasts. Vehicles equipped with a Kong-ported blower, Magnuson 2650, or Whipple supercharger often reach the point where the additional airflow capacity of the 103mm becomes beneficial, particularly when paired with supporting modifications such as aftermarket camshafts, improved cylinder heads, or increased engine speed.

Unlike many oversized throttle bodies that are selected simply because they're larger, the 103mm strikes an outstanding balance between airflow, responsiveness, and future growth. It provides enough capacity for the overwhelming majority of high-performance street builds while preserving excellent throttle modulation and drivability.

Perhaps most importantly, it's a proven solution. Our own shop Camaro ZL1, producing over 900 rear-wheel horsepower with a Kong-ported LT4 supercharger, utilizes the Katech 103mm Billet Throttle Body because it delivers exactly what that combination requires, excellent airflow without unnecessary compromise.

Best Applications

• Kong-ported LT4 superchargers

• Magnuson 2650 systems

• Whipple 2.9L and many 3.0L combinations

• Aggressive camshaft and cylinder head packages

• Builds targeting approximately 800–1,100rwhp horsepower

Griffin Motorsports Insight

If a customer calls us describing a serious street-driven LT4 with future horsepower goals, the Katech 103mm is usually where the conversation begins. It offers the versatility, airflow capacity, and OEM-level refinement that make it one of the best all-around throttle body upgrades available for the platform.

Katech 112mm Billet Throttle Body

At the top of our LT4 lineup sits the Katech 112mm Billet Throttle Body, engineered for combinations where maximum airflow is the priority.

With its massive throttle blade, 5-axis CNC-machined billet construction, and genuine GM electronics, the 112mm is designed for engines capable of consuming an extraordinary amount of air. This isn't simply a larger version of the 103mm, it is a purpose-built component intended for combinations that have surpassed the airflow requirements of more conventional street builds.

Vehicles equipped with large-displacement positive displacement superchargers, maximum-effort Whipple combinations, fully built engines, extensive cylinder head development, and aggressive camshaft packages are where the 112mm truly shines. At this level, every restriction matters, and ensuring the throttle body is no longer part of the equation becomes increasingly important.

However, it's equally important to understand that the 112mm is not a universal upgrade.

Installing a 112mm throttle body on a relatively mild LT4 combination rarely produces the same benefits seen on an engine specifically engineered to consume that level of airflow. Without the supporting modifications to justify its capacity, much of its potential simply goes unused.

Best Applications

• Large Whipple and Magnuson combinations 

• Dedicated competition vehicles

• Customers pursuing the highest possible horsepower levels

Which One Is Right for You?

If you're still unsure which throttle body best fits your combination, remember this simple principle:

If your goal is to enhance a stock or mildly modified LT4 while preserving factory drivability, the Katech CNC Ported 95mm is difficult to beat.

If you're building a serious street car with a ported blower, Magnuson 2650, Whipple, or supporting airflow modifications, the Katech 103mm Billet represents the ideal balance of airflow, refinement, and future flexibility.

If your engine has evolved into a purpose-built, maximum-effort combination where every component has been optimized to support extraordinary airflow, the Katech 112mm Billet ensures the throttle body is no longer the limiting factor.

The best throttle body isn't determined by its diameter. It's determined by how well it complements the complete airflow package—and that's the philosophy behind every recommendation we make at Griffin Motorsports.