Cylinder Heads

What Are Cylinder Heads and Why Do They Matter?

The cylinder head sits atop the engine block, sealing the combustion chamber and serving as the gateway for airflow in and exhaust gases out. It houses the intake and exhaust valves, valve springs, and spark plug ports — making it one of the most performance-critical components in any internal combustion engine. Whether you're rebuilding a tired motor or chasing more horsepower on a dedicated race build, the cylinder head is where power is made or lost.

Upgrading to a performance cylinder head can dramatically improve throttle response, top-end horsepower, and overall engine efficiency. Heads can enhance power and performance if they're designed for higher compression or feature larger valves and optimized port geometry for better breathing. When properly matched with a performance camshaft and exhaust headers, a quality set of cylinder heads can unlock significant horsepower gains that simply aren't achievable through tuning alone.

Bare vs. Assembled Cylinder Heads

When shopping for cylinder heads, one of the first decisions you'll face is whether to buy a bare casting or a fully assembled head. Bare heads are ideal for experienced engine builders who want to spec their own valvetrain components — valve sizes, spring pressures, and retainer types — tailored to a specific camshaft profile. Assembled heads come ready to install with stainless steel valves, valve springs, seals, locks, and retainers already in place, saving time and ensuring compatibility. Many performance heads also come in as-cast or CNC-ported versions, with CNC porting delivering tighter tolerances and more consistent airflow across all cylinders.

Key Considerations When Buying Cylinder Heads

• Material: Aluminum heads are lighter and dissipate heat more efficiently than cast iron, making them popular for performance builds. Cast iron heads are heavier but more affordable and durable for mild street use.
• Port Volume & Design: Intake runner volume should be matched to your engine's displacement and RPM range. Smaller ports increase velocity for better low-end torque; larger ports support higher RPM power.
• Combustion Chamber Volume: Chamber size directly affects compression ratio. Smaller chambers raise compression; larger chambers lower it. Always verify compatibility with your pistons and intended fuel type.
• Valve Size: Larger valves allow more airflow but must be matched to your cam profile and port design. Oversized valves on the wrong head can actually hurt low-RPM performance.
• Compatibility: Always confirm fitment with your engine family, block generation, and camshaft type — flat tappet, hydraulic roller, or solid roller.

Top Cylinder Head Brands

For budget-conscious performance builds, Speedmaster offers an accessible entry point into the world of performance cylinder heads. Their lineup includes both as-cast and CNC-ported aluminum heads for popular Chevy, Ford, and Pontiac V8 platforms. Speedmaster's as-cast heads are designed for street performance and entry-level racing, while their CNC-ported versions feature combustion chambers and runners machined to within .002-inch tolerance for equalized compression and airflow across all cylinders.

For racers and serious performance enthusiasts who demand the highest quality, Dart is a name that needs no introduction. Founded in 1981, Dart has become a proven leader in aftermarket cylinder heads, with roots in NHRA Pro Stock racing. Their heads — including the iconic Pro 1 and Iron Eagle lines — are engineered to maximize airflow for Big Block Chevy, Small Block Chevy, Small Block Ford, and GM LS engines, and are trusted by professional engine builders worldwide.

Rounding out the lineup, Pro Design provides additional options for builders looking to explore specialized cylinder head solutions for their specific applications.