1. What is Cam Duration?

Cam duration refers to the angular measurement from when a cam begins to open a valve until it completely closes it. This measurement is critical in engine design and performance tuning as it determines how long valves remain open during the engine cycle.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( Duration \) — The cam duration in degrees
• \( \text{angle from open to close} \) — The angular measurement between valve opening and closing points

Explanation: The duration is simply the angular distance the cam rotates from the point where the valve begins to open until it completely closes.

3. Importance of Cam Duration Calculation

Details: Accurate cam duration calculation is crucial for engine performance tuning, valve timing optimization, and ensuring proper engine operation across different RPM ranges.

4. Using the Calculator

Tips: Enter the measured angle from valve open to valve close in degrees. The value must be a positive number greater than 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between advertised duration and duration at 0.050" lift?
A: Advertised duration is measured from the very beginning of valve movement, while duration at 0.050" lift is measured from when the valve has lifted 0.050 inches off the seat.

Q2: How does cam duration affect engine performance?
A: Longer durations generally increase high-RPM power but may reduce low-RPM torque. Shorter durations typically improve low-end torque but limit top-end power.

Q3: What is a typical cam duration range?
A: Street performance cams typically range from 200-280 degrees, while race cams can exceed 300 degrees of duration.

Q4: How is cam duration measured in practice?
A: Duration is measured using a degree wheel mounted on the crankshaft while monitoring valve movement with a dial indicator.

Q5: Does cam duration affect fuel economy?
A: Yes, longer cam durations typically reduce fuel economy at low RPMs due to reduced cylinder filling efficiency, while shorter durations can improve low-RPM efficiency.