Understanding Jet Ski Impeller Pitch Numbers To Choose The Right Impeller

What Do the Numbers Mean?

Impeller pitch is typically denoted by two numbers, such as 13/19 or 14/22. These numbers represent the pitch angle of the impeller blades at their leading and trailing edges, measured in degrees.

• First Number: The first number (e.g., 13 in 13/19) refers to the angle of attack at the leading edge of the impeller blades. This angle determines how aggressively the impeller scoops water. A smaller number indicates a lower angle, which scoops water more aggressively, aiding in quicker acceleration.

• Second Number: The second number (e.g., 19 in 13/19) refers to the trailing edge’s angle. This angle affects how efficiently the water is expelled out the back of the impeller, influencing the jet ski’s top speed. A higher second number means a more gradual expulsion of water, which is beneficial for higher top speeds.

How These Numbers Affect Jet Ski Performance

• Lower First Number: Indicates a more aggressive pitch that increases low-speed thrust and acceleration. It’s ideal for those who need quick starts or have heavy loads.

• Higher Second Number: Indicates a pitch designed for higher speeds, as it allows the impeller to push water out more smoothly over a longer distance, enhancing sustained speed.

Choosing the Right Impeller Based on Numbers

When selecting an impeller, consider your typical usage scenarios and the performance characteristics you most value:

1. For Enhanced Acceleration:

   • Choose an impeller with a lower first number and a moderate second number, such as 12/17 or 13/18. This setup provides a good balance between aggressive water intake and efficient expulsion, boosting acceleration without severely compromising top speed.

2. For Maximum Top Speed:

   • Opt for an impeller with a higher set of numbers, such as 14/22 or 15/23. These impellers are less aggressive at scooping water but are excellent at maintaining a high flow rate, which is essential for achieving high top speeds.

3. For Balanced Performance:

   • Consider impellers that have a moderate pitch, like 13/19 or 14/20. These offer a reasonable compromise between acceleration and top speed, making them suitable for general use.

Tips for Choosing Your Impeller

• Consult with Experts: Always consult with a marine mechanic or a jet ski performance specialist who can offer personalized advice based on your jet ski model and usage.

• Consider Engine Modifications: If you have modified your engine for higher performance, you might need a different impeller pitch to match the increased power.

• Test Different Pitches: If possible, try out different impellers to feel how they affect performance firsthand. This experience can be invaluable in choosing the right pitch for your needs.

By understanding how the numbers on an impeller pitch can affect your jet ski’s performance, you can make a more informed decision that enhances your riding experience.