What Does a Bigger Camshaft Do: Unleashing Vehicle Performance Secrets

by

A bigger camshaft can significantly impact vehicle performance by altering the engine’s powerband, torque curve, and overall output. The primary function of a camshaft is to control airflow into and out of the engine cylinders, and a larger camshaft can modify these flows in several ways, unleashing a new level of performance.

Duration: Extending Valve Open Time

A bigger camshaft typically has longer duration, which refers to the amount of time the valves are open. This extended duration allows more air and fuel to enter the cylinders, increasing the engine’s power output. For example, a high-performance camshaft with 260-280 degrees of duration can provide an additional 20-30 horsepower compared to a stock camshaft with 220-240 degrees of duration. However, this extended duration can also affect drivability, as longer duration cams can result in a narrower powerband and reduced low-end torque.

Lift: Raising Valve Lift

what does a bigger camshaft do unleashing vehicle performance secrets

A larger camshaft also increases valve lift, which is the distance the valves are opened. Greater lift allows more air and fuel to enter the cylinders, enhancing combustion and power output. A stock camshaft may have a valve lift of 0.400-0.450 inches, while a larger performance camshaft can have a lift of 0.500-0.550 inches, resulting in a 10-15% increase in airflow. However, excessive lift can lead to valve float, where the valves cannot close quickly enough, causing reliability issues and potentially damaging the engine.

Overlap: Balancing Intake and Exhaust

The overlap period is when both the intake and exhaust valves are open simultaneously. A larger camshaft can increase overlap, which can improve volumetric efficiency but may negatively impact low-end torque and drivability. For example, a stock camshaft may have an overlap of 40-50 degrees, while a larger performance camshaft can have an overlap of 60-70 degrees. Properly managing overlap is crucial for achieving the desired powerband and torque curve, as too much overlap can result in a peaky power delivery and poor low-end response.

Valve Timing: Optimizing Power Delivery

A bigger camshaft can alter valve timing, affecting the engine’s performance across the RPM range. Early intake valve opening can improve low-end torque, while late intake valve closing can enhance high-end power. For instance, a stock camshaft may have an intake valve opening of 10-15 degrees before top dead center (BTDC) and a closing of 50-55 degrees after bottom dead center (ABDC), while a larger performance camshaft can have an opening of 20-25 degrees BTDC and a closing of 60-65 degrees ABDC. Adjusting valve timing is a critical aspect of camshaft selection and engine tuning, as it allows you to tailor the power delivery to your specific needs.

Airflow Management: Optimizing Cylinder Filling and Scavenging

A larger camshaft can better manage airflow into and out of the engine, optimizing cylinder filling and scavenging. This results in improved combustion efficiency, power output, and torque curve. For example, a stock camshaft may have a peak flow of 200-220 CFM (cubic feet per minute), while a larger performance camshaft can have a peak flow of 240-260 CFM, representing a 10-15% increase in airflow capacity. Proper airflow management is essential for unlocking the full potential of a larger camshaft.

In summary, a bigger camshaft can significantly impact vehicle performance by altering the engine’s powerband, torque curve, and overall output. By managing duration, lift, overlap, valve timing, and airflow, a larger camshaft can provide increased power and torque, but at the cost of reduced drivability and potential reliability issues if not properly tuned and managed. Understanding these performance secrets is crucial for enthusiasts and tuners looking to unleash the full potential of their vehicle’s engine.

References: