1. What is Valve Lift Calculation?

Valve lift calculation determines how far the valves open in an engine based on camshaft specifications and rocker arm ratio. It's a critical measurement for engine performance and airflow optimization.

2. How Does the Calculator Work?

The calculator uses the valve lift formula:

Where:

• Cam Lobe Lift — The maximum lift of the camshaft lobe (inches)
• Rocker Ratio — The mechanical advantage of the rocker arm (unitless)

Explanation: The rocker arm multiplies the cam lobe lift to determine how far the valve actually opens in the cylinder head.

3. Importance of Valve Lift Calculation

Details: Accurate valve lift calculation is essential for engine building, performance tuning, and ensuring proper valve-to-piston clearance. It directly affects engine breathing, power output, and volumetric efficiency.

4. Using the Calculator

Tips: Enter cam lobe lift in inches and rocker ratio (typically between 1.5-1.8 for most engines). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical rocker ratio for performance engines?
A: Most performance engines use rocker ratios between 1.5:1 and 1.8:1, with 1.6:1 and 1.7:1 being most common.

Q2: How does valve lift affect engine performance?
A: Higher valve lift typically improves airflow and power, but must be balanced with proper valve spring pressure and piston-to-valve clearance.

Q3: Can I change rocker ratio without changing camshaft?
A: Yes, changing rocker arms is a common method to alter valve lift without replacing the camshaft, but requires checking clearances and spring pressures.

Q4: What's the difference between theoretical and actual valve lift?
A: Theoretical lift is calculated as shown here, while actual lift may be slightly less due to valvetrain deflection under load.

Q5: How do I measure cam lobe lift?
A: Cam lobe lift is measured as the difference between the base circle radius and the lobe peak radius, typically provided in camshaft specifications.