1. What is Valve Lift?

Valve lift refers to the maximum distance that a valve opens from its seat in an internal combustion engine. It's a critical measurement that affects engine breathing, performance, and efficiency.

2. How Does the Calculator Work?

The calculator uses the valve lift formula:

Where:

• Cam Lift — The maximum lift of the camshaft lobe (in inches or millimeters)
• Rocker Ratio — The mechanical advantage provided by the rocker arm (dimensionless)

Explanation: The rocker arm multiplies the camshaft's lobe lift to create greater valve movement. This simple multiplication gives the actual valve lift at the valve stem.

3. Importance of Valve Lift Calculation

Details: Accurate valve lift calculation is essential for engine builders and tuners to optimize airflow, select appropriate valve springs, prevent valve-to-piston contact, and maximize engine performance.

4. Using the Calculator

Tips: Enter cam lift in either inches or millimeters (be consistent with units). Enter the 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: Does valve lift affect engine performance?
A: Yes, increased valve lift typically improves airflow and horsepower, but only up to the point where the port becomes inefficient or valve train stability is compromised.

Q3: Can I mix measurement units?
A: No, be consistent with your units. If you input cam lift in inches, the result will be in inches. If you input in millimeters, the result will be in millimeters.

Q4: What factors limit maximum valve lift?
A: Valve-to-piston clearance, coil bind of valve springs, retainer-to-seal clearance, and the camshaft's lobe design itself all limit maximum achievable valve lift.

Q5: How does rocker ratio affect valve acceleration?
A: Higher rocker ratios not only increase lift but also increase valve acceleration rates, which can affect valve train stability and require stronger valve springs.