The Top 10: Best Flowing SBC Heads in 2024
The roar of a finely-tuned Small Block Chevy is music to any gearhead’s ears. The rumble hints at contained violence, a sense of coiled potential waiting to be unleashed. Since its introduction, the SBC has become synonymous with raw American horsepower, adaptability, and a vast aftermarket that lets builders tailor it for nearly any purpose. At the heart of this legendary engine lies a deceptively simple component – the cylinder head. It’s here, within those metal castings, that power is truly born. The SBC’s personality, whether it’s a torquey street bruiser or a high-revving screamer, is determined in large part by the flow characteristics of its heads.
Key Takeaways:
- Optimal Airflow: The best-flowing SBC heads are designed to maximize airflow, which is essential for improving engine efficiency and power output.
- Material Quality: High-grade materials such as aluminum and advanced alloys ensure durability and heat dissipation, contributing to the longevity and performance of the engine.
- Compatibility: It’s important to choose heads that are compatible with your specific SBC engine model and setup to avoid installation issues and achieve the desired performance enhancements.
- Valve Technology: Advanced valve designs and technologies play a significant role in the performance of SBC heads, influencing airflow and engine responsiveness.
- Port Design: The shape and size of the intake and exhaust ports affect the head’s ability to flow air and exhaust gases, impacting overall engine performance.
- Brand Reputation: Selecting SBC heads from reputable manufacturers ensures reliability, quality, and access to support and warranties.
Deciphering the Secrets of Cylinder Head Flow
CFM: More Than Just a Number
Flow numbers, often expressed as CFM (Cubic Feet per Minute), get tossed around liberally when discussing cylinder heads. But those numbers are merely the tip of the iceberg. Think of CFM as telling you how much air a head can potentially move, but not necessarily how efficiently. To truly understand flow, we need to consider how the test was conducted, on what type of flow bench, and at what test pressure. Different flow benches can yield varying results, but a standard is typically 28 inches of water for test pressure. This information is crucial when comparing heads, to make sure you have apples-to-apples data.
The Magic of Runner Design
CFM gives us a starting point, but it’s the shape and size of the intake and exhaust runners within the head that truly dictate power delivery. Think of port volume like a pipe – a bigger pipe can flow more total volume, but if the fluid is moving too slowly, it’s inefficient. In an engine, intake port velocity is critical for low and mid-range torque. Smaller, higher velocity runners help atomize fuel and maintain quick cylinder filling at lower RPMs. Conversely, if your goal is peak top-end horsepower, larger runners come into play, as the engine’s breathing demands increase at high RPM.
However, it’s not just about runner volume. Port shape also plays a massive role. Smoother transitions, carefully designed turns, and maximizing cross-sectional area throughout the port all contribute to minimizing turbulence and improving airflow. This is where CNC-ported heads can have an advantage, allowing for intricate shapes that would be difficult or impossible to achieve with hand porting.
Combustion Chamber Chronicles
Once air and fuel rush into the cylinder through the intake port and valve, they find themselves in the combustion chamber. It might look like a simple space, but its design has enormous implications for power, efficiency, and how resistant the engine is to detonation (knock). Within the chamber, areas known as “quench zones” play a critical role. These are tighter regions around the perimeter of the cylinder where the piston comes very close to the cylinder head. This rapid squeeze and mixing of air and fuel as the piston reaches top-dead-center promotes a more complete and rapid burn for improved power.
Another factor is valve shrouding. Imagine the valve opening into the chamber – if the chamber wall is too close to the edge of the valve, it can restrict airflow, especially at lower valve lifts. Careful chamber shaping minimizes shrouding, leading to better cylinder filling. Finally, spark plug location matters. Ideally, you want the spark plug positioned for the flame to spread in the most efficient way possible across the piston. Modern heads often have the spark plug angled slightly to optimize this flame propagation.
Unlocking the Valve Curtain
Big valves are a common focus when talking about high-flow heads, and for good reason. A larger valve presents a bigger opening for air to flow through. However, it’s not just the diameter that matters. Consider the valve like a doorway – even if you install a massive door, it won’t do much good if you only open it a tiny crack. This is where the camshaft’s lift profile comes in. Higher lift means the valve is opened further, maximizing airflow potential. Additionally, the way the valve opens and closes (the ramp rate of the camshaft lobe) has a significant impact on the overall efficiency of how air moves through the port.
Beyond lift, a concept called “effective flow area” helps us understand true flow potential. Imagine looking down the intake port directly at the back of the intake valve. Even when fully open, the valve stem and guide still partially obstruct the port. Techniques like back-cutting valves, where a portion of the valve’s backside is machined at an angle, can increase effective flow area and provide performance gains, especially at lower valve lifts.
Materials and Machining: From Castings to CNC Masterpieces
The journey of a performance cylinder head begins with the raw material – typically an aluminum alloy. The specific alloy used impacts the head’s strength, weight, and thermal properties. Most aftermarket SBC heads utilize some form of cast aluminum. In its most basic form, a head starts as a casting, with the ports and chambers roughly formed. From here, the level of machining and finishing is what separates the contenders.
Budget-friendly heads may have minimal machining – just enough to ensure proper fitment of valves and other components. These heads offer performance gains over stock units but leave room for improvement in terms of maximizing flow. Semi-finished heads arrive with the ports and chambers roughed out, ready for a skilled engine builder or porter to apply their expertise to fine-tune the shapes for a specific application.
At the pinnacle of performance are fully CNC-ported heads. These masterpieces utilize computer-controlled machining to achieve extreme precision and complex port shapes. CNC porting opens up possibilities that traditional hand-porting can’t easily match, maximizing flow and consistency from cylinder to cylinder. However, this precision comes at a price, making CNC-ported heads the most expensive option.
Top 10 Best Flowing SBC Heads Review
1. Edelbrock 5089 Cylinder Head
- Complete Pair For Hydraulic Flat Tappet
- 64cc Combustion Chamber Volume
- 2. 02cc Intake/60cc Exhaust Runner Volume
- 2. 02 in. Intake/1. 6 in. Exhaust Valve Diameter
- 0. 562 in. Deck Thickness
This set stands out for its robust build and performance-enhancing features. It’s designed for those looking for reliable performance enhancements. It includes premium steel construction, manganese bronze guides, and a 70cc combustion chamber to improve efficiency. Although it’s on the heavier side, its easy installation, durability, and excellent performance make it a great choice for daily use.
2. Assault Racing Products SBC20064SC Cylinder Head
- 200CC Intake Runner
- 64CC Combustion Chamber
- 2.02/1.6 Valves / .550 Springs
- Straight Plug
- Aluminum
Ideal for upgrading from stock settings without going overboard. With a 200cc intake port and a 64cc combustion chamber, this cylinder head offers a moderate performance boost. Its high-grade aluminum alloy construction and manganese bronze valve guides enhance durability and airflow, making it suitable for street use. It’s noted for its good casting quality and visually pleasing machining work, although it might not be the best pick for high-performance engines.
3. SAE Speed 2X Bare Cylinder Heads
Known for its air-gap design, which keeps the fuel/air mixture cooler, thus enhancing performance. These heads fit SBC engines up to 1986 and feature a 64cc combustion chamber that helps maintain stock compression ratio. They are praised for increasing power output across the entire band and improving fuel economy. However, they might be considered pricey by some
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Chevrolet Cylinder Head: Aimed at delivering top-notch performance, this head incorporates Fast Burn technology for efficient combustion. It’s CNC-machined for consistent performance and is designed to work with flat top pistons. It’s considered one of the highest performing 23-degree SBC heads, especially suitable for drag racing, with its universal fit and no need for additional porting for most applications. However, for all-out race activities, further porting might be necessary
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Dart 10024360 Dart Machinery Cylinder Head: This is a top pick for those looking to maximize airflow efficiency and engine performance. It’s designed with optimized intake and exhaust ports and carefully engineered combustion chambers to enhance horsepower and torque output. It’s an excellent choice for small-block chevy enthusiasts aiming to improve their engine’s overall performance and responsiveness.
Dart SHP 180cc 23° for Small Block Chevy: This head is designed for street performance engines, offering an affordable choice for those seeking the benefits of aluminum heads. It’s optimized for maximum torque and throttle response up to 6,000 RPM, making it ideal for 327 – 400 cubic inch engines. The precision cast ports and optimized chambers improve flow and performance without the need for CNC porting
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Dart SHP 200cc 23° for Small Block Chevy: Similar to the 180cc version but with larger 200cc intake ports, these heads are meant for larger displacement engines, providing best performance from mid-range to 6,500 RPM. They’re suitable for 383 – 434 cubic inch engines and also feature precision cast ports and optimized chambers for improved flow and power
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Dart SHP 175cc 20° for Small Block Ford: These heads offer an affordable aluminum head option for street performance engines, with precision cast ports and optimized chambers that enhance flow and power without CNC porting. They are designed to work with most off-the-shelf components and increase combustion efficiency
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Dart SHP 205cc 20° for Small Block Ford: Offering a larger intake port volume for those needing more airflow, these heads are designed similarly to the 175cc version but are tailored for engines requiring higher airflow. They maintain the same quality features such as manganese bronze valve guides and are designed to improve combustion efficiency and performance
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Casting Numbers 441 and 487: For a more traditional approach, heads with casting numbers 441 or 487 are often recommended within the community for their flow characteristics and potential for performance improvements. The 487 casting, in particular, is noted for its larger port volume which could potentially sustain higher peak horsepower without a quick drop-off. These heads, especially when worked over, can offer significant performance enhancements for your SBC engine.
