1. What is Rocker Ratio?

The rocker ratio is a mechanical advantage factor in valve train systems that determines how much the valve lifts relative to the camshaft lobe lift. It's a critical parameter in engine performance tuning.

2. How Does the Calculator Work?

The calculator uses the rocker ratio formula:

Where:

• Lift at Valve — Maximum valve lift measurement (in inches)
• Lift at Cam — Corresponding camshaft lobe lift (in inches)

Explanation: The ratio represents the mechanical advantage provided by the rocker arm assembly in converting camshaft motion to valve movement.

3. Importance of Rocker Ratio

Details: The rocker ratio directly affects valve timing, duration, and lift characteristics. Different ratios can significantly impact engine performance, airflow, and power output across the RPM range.

4. Using the Calculator

Tips: Enter both lift measurements in inches. Ensure measurements are taken accurately at maximum lift points. Both values must be greater than zero for valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical rocker ratio range?
A: Most production engines use ratios between 1.5:1 and 1.7:1, while performance engines may use ratios up to 2.0:1 or higher.

Q2: How does rocker ratio affect valve lift?
A: Higher ratios increase valve lift for a given cam profile, potentially improving airflow but requiring stronger valve springs and components.

Q3: Can I change rocker ratios on any engine?
A: Not all engines allow easy ratio changes. Modifications may require different rocker arms, pushrods, and possibly cylinder head modifications.

Q4: Does rocker ratio affect valve timing?
A: While the ratio primarily affects lift, it can slightly alter valve timing events due to changes in the valve train geometry.

Q5: How do I measure lift at valve and cam accurately?
A: Use a dial indicator to measure maximum lift at both the valve tip (for valve lift) and at the pushrod or lifter (for cam lift).