Performance Camshaft Buying Guide

A performance camshaft is a pivotal component for anyone looking to enhance their engine’s power and efficiency. Selecting the correct performance camshaft, however, can be a complex task given the multitude of options and technical specifications involved. This guide aims to demystify the process, providing you with the essential knowledge needed to make an informed purchase and truly upgrade your vehicle’s capabilities.

Understanding the Role of a Performance Camshaft

Before diving into the specifics of a performance camshaft, it’s important to understand its fundamental role. The camshaft controls the opening and closing of your engine’s intake and exhaust valves, dictating when and how much air and fuel enter, and exhaust gases exit, the combustion chambers. A performance camshaft is designed with different lobe profiles compared to a stock cam, allowing for increased valve lift, duration, and overlap, which ultimately improves horsepower and torque output.

What Makes a Camshaft a “Performance” Camshaft?

Unlike factory camshafts optimized for broad drivability and emissions, a performance camshaft prioritizes power gains. These cams typically feature more aggressive lobe designs. This translates to valves opening higher and staying open longer, allowing for greater airflow into and out of the engine. The result is often a noticeable increase in power, particularly at higher RPMs, though sometimes at the expense of low-end torque or idle quality.

Key Factors to Consider Before Your Purchase

Before you even look at specific performance camshaft specifications, several overarching factors should guide your decision-making process. These considerations will narrow down your options significantly.

Vehicle Application and Engine Type: Understand your engine’s specific make, model, and year. Different engines have different valvetrain designs and space constraints that influence performance camshaft compatibility.
Intended Use: Will your vehicle be primarily a street cruiser, a drag strip contender, a road course racer, or a combination? A performance camshaft optimized for drag racing will likely be too aggressive for comfortable street driving.
Transmission Type: Manual or automatic transmission can influence cam choice. Automatics, especially with higher stall converters, can often handle more aggressive cams than stock automatics or manual transmissions on the street.
Existing and Planned Modifications: Your performance camshaft should complement other engine modifications. Headers, intake manifolds, cylinder heads, forced induction, and tuning all work together. A cam that’s too large for stock components won’t yield optimal results.
Budget: Performance camshafts vary widely in price. Factor in not just the cam itself, but also supporting components like valve springs, pushrods, lifters, and the cost of professional installation and tuning.

Decoding Performance Camshaft Specifications

Understanding the technical jargon associated with a performance camshaft is essential. These numbers directly dictate how the cam will perform.

Lift: How High the Valves Open

Valve lift refers to how far the valve is pushed open off its seat. Measured in inches (e.g., .550"), higher lift generally allows more air to flow through the cylinder head. However, too much lift can lead to valve-to-piston clearance issues or require stronger valve springs to prevent valve float.

Duration: How Long the Valves Stay Open

Duration is the amount of time, measured in crankshaft degrees, that the valve remains open. It’s often expressed in two ways:

Advertised Duration: This is the total number of crankshaft degrees the valve is off its seat, typically measured at a very small lift point (e.g., .006").
Duration at .050" Lift: This is a more accurate and commonly used specification, measuring the duration when the valve is lifted at least .050" off its seat. Higher duration generally moves the power band higher in the RPM range.

Lobe Separation Angle (LSA): The Relationship Between Lobes

LSA is the angle in crankshaft degrees between the centerline of the intake and exhaust lobes. This specification significantly impacts a performance camshaft’s characteristics:

Wide LSA (112-116 degrees): Provides a smoother idle, broader power band, better vacuum, and is generally more street-friendly.
Tight LSA (106-110 degrees): Often results in a choppier idle, narrower but more aggressive power band, and higher peak horsepower.