1. What is Rocker Ratio Lift?

The rocker ratio is the mechanical advantage provided by the rocker arm in an engine's valvetrain. It determines how much the valve opens (valve lift) based on the camshaft's lobe lift (cam lift).

2. How Does the Calculator Work?

The calculator uses the valve lift formula:

Where:

• \( \text{Valve Lift} \) — Distance the valve opens (mm)
• \( \text{Cam Lift} \) — Maximum lobe height of camshaft (mm)
• \( \text{Ratio} \) — Rocker arm ratio (dimensionless)

Explanation: The rocker arm multiplies the camshaft's lift by its ratio to determine how far the valve opens.

3. Importance of Valve Lift Calculation

Details: Proper valve lift is crucial for engine performance. Too little lift restricts airflow, while too much can cause valve-to-piston contact.

4. Using the Calculator

Tips: Enter cam lift in millimeters and rocker ratio as a decimal (e.g., 1.6:1 ratio is entered as 1.6). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical rocker ratio?
A: Most production engines use ratios between 1.5:1 and 1.8:1, while performance engines may use higher ratios.

Q2: How do I measure cam lift?
A: Measure the difference between the base circle and highest point of the cam lobe with a dial indicator.

Q3: Can valve lift exceed cam lift?
A: Yes, when using a rocker ratio greater than 1:1, which is common in most engines.

Q4: What affects maximum valve lift?
A: Valve spring pressure, piston-to-valve clearance, and valve train geometry all limit maximum lift.

Q5: How does ratio affect performance?
A: Higher ratios increase valve lift without changing cam profile, but may require stronger valve springs.