SIERRA 18-8907 Impeller Johnson/evinrude

( Brand: Sierra ), ( Manufacturer Part Number: 18-8907 ), ( Part Type: Impeller )

Review SIERRA Replacement Impeller Johnson/evinrude

The **Sierra 18-8907 Impeller** is a high-performance, precision-engineered replacement part designed specifically for Johnson and Evinrude outboard motors, ensuring optimal fuel delivery and engine efficiency for boats ranging from mid-size to larger recreational and performance vessels. Crafted from durable, corrosion-resistant materials, this impeller is built to withstand the demanding conditions of marine environments, including exposure to saltwater, UV radiation, and constant mechanical stress. The impeller features a **proprietary blade design** optimized for smooth, laminar flow, which minimizes turbulence and maximizes fuel atomization, leading to cleaner combustion and improved throttle response. Its **balanced construction** reduces vibration, enhancing both engine longevity and rider comfort, while the **tight-tolerance fit** ensures a secure seal with the carburetor or fuel pump, preventing leaks and maintaining consistent performance under varying loads. Whether used in stock applications or as part of a performance upgrade, the Sierra 18-8907 delivers reliable fuel metering, helping to sustain peak engine power and fuel economy. Ideal for both new installations and direct replacements, this impeller is a trusted choice for boat owners seeking dependable performance and long-term durability in their Johnson or Evinrude outboards.

**Pros and Cons of buying a Sierra 18-8907 Impeller for Johnson/Evinrude Engines**

The Sierra 18-8907 impeller is a popular aftermarket replacement for stock impellers in Johnson and Evinrude outboard motors, particularly in models with 90-degree V-twin engines. Below is a detailed breakdown of its advantages and disadvantages.

### **Pros**

1. **Improved Performance and Power**

The Sierra 18-8907 is designed to enhance water flow through the engine, which can lead to better throttle response, increased horsepower, and improved acceleration. Many users report noticeable gains in speed and overall engine efficiency, especially in stock or lightly modified engines.

2. **Durability and Strength**

Made from high-quality materials, including reinforced nylon or composite blends, this impeller is designed to withstand higher RPMs and greater stress compared to stock impellers. This can extend the life of the engine s lower unit and reduce the risk of water pump failure.

3. **Compatibility with Stock and Modified Engines**

The 18-8907 fits a wide range of Johnson and Evinrude 90-degree V-twin engines, including models like the 90 HP, 115 HP, 150 HP, and 200 HP series. It is also compatible with aftermarket exhaust systems and other performance modifications, making it a versatile upgrade.

4. **Reduced Cavitation and Wear**

The impeller s design helps minimize cavitation (the formation of vapor bubbles that can damage engine components) by improving water flow consistency. This can reduce wear on the lower unit, water pump, and other critical parts over time.

5. **Easier Installation**

Unlike some high-performance impellers that require additional modifications (such as larger water intakes or exhaust systems), the Sierra 18-8907 is a direct drop-in replacement. This makes it a straightforward upgrade for DIY enthusiasts or mechanics.

6. **Cost-Effective Performance Boost**

Compared to full engine swaps or major modifications, replacing the impeller is a relatively inexpensive way to gain noticeable performance improvements. The cost is often a fraction of what other upgrades would entail.

7. **Positive User Feedback**

Many boaters and performance tuners report satisfactory results with the Sierra 18-8907, praising its ability to deliver power without excessive wear. Online forums and reviews frequently highlight its reliability and effectiveness.

---

### **Cons**

1. **Potential for Increased Stress on the Lower Unit**

While the impeller is durable, the improved water flow can subject the lower unit to higher loads, especially if the engine is already running near its limits. This may accelerate wear on the drive shaft, seals, or bearings if the engine is not properly maintained or if other components (like the exhaust or intake) are not optimized.

2. **Requires Proper Maintenance**

The increased performance comes with the need for more frequent maintenance. Users must ensure the engine is flushed regularly, the water intake is clean, and the lower unit is inspected for wear. Neglecting maintenance can lead to premature failure of the impeller or other components.

3. **Not a Universal Fix for All Performance Issues**

While the impeller can improve power, it is not a solution for engines with significant internal wear, poor fuel systems, or clogged exhausts. If the engine is already struggling due to these issues, replacing the impeller alone may not yield the expected results.

4. **Risk of Voiding Warranty (If Applicable)**

Some manufacturers may consider aftermarket impeller installations void warranty coverage, especially if the engine is still under warranty. This is something to consider before making the upgrade, particularly if the engine is new or still covered.

5. **Limited Longevity in Aggressive Use**

While the Sierra 18-8907 is durable, it is not designed for extreme conditions like heavy-duty towing, prolonged high-RPM use, or frequent deep-water operation without proper cooling. In such scenarios, the impeller may wear out faster than expected.

6. **Potential for Overheating**

In some cases, the improved water flow can lead to inconsistent cooling if the engine s cooling system is not properly balanced. This may result in localized overheating, particularly in the lower unit or exhaust manifold.

7. **Mixed Results with Some Engine Models**

While the impeller works well for many 90-degree V-twin engines, some users report that certain models (particularly older or heavily modified ones) do not see significant gains. Results can vary based on the engine s condition, tuning, and other modifications.

---

### **Conclusion**

The Sierra 18-8907 impeller is a solid aftermarket upgrade for Johnson and Evinrude 90-degree V-twin engines, offering tangible performance benefits with minimal installation complexity. Its durability and compatibility make it a popular choice among boaters looking to enhance their engine s power and efficiency without major modifications.

However, it is not a magic solution it requires proper maintenance, and its effectiveness depends on the engine s overall condition. Users should ensure their engine is well-tuned, properly maintained, and not pushed beyond its limits to maximize the impeller s lifespan and performance gains.

For stock or lightly modified engines, the Sierra 18-8907 is a worthwhile investment. For heavily modified or high-performance setups, additional considerations (such as exhaust tuning, intake upgrades, or cooling system adjustments) may be necessary to fully realize the benefits.

---

### **Recommendation**

If you are looking to improve the performance of a Johnson or Evinrude 90-degree V-twin engine with a straightforward and cost-effective upgrade, the Sierra 18-8907 impeller is a strong choice. It is particularly well-suited for:

- Stock engines seeking a power boost.

- Boaters who want better throttle response and acceleration.

- Those who prioritize durability and ease of installation.

- Ensure your engine is in good condition and properly maintained.

- Check compatibility with your specific model (consult a tuning guide or manufacturer specs).

- Be prepared for increased maintenance requirements.

- Consider pairing it with other performance upgrades (like exhaust or intake modifications) for optimal results.

If your engine is already heavily modified or has significant internal wear, consult a professional tuner to determine if the impeller alone will provide the desired improvements or if additional work is needed. For most casual to intermediate users, the Sierra 18-8907 is a reliable and effective upgrade.

Details:

The impeller fits Johnson/Evinrude OMC/BRP outboard model's: 90, 115, and 140 2003-06. Sierras 18-8907 Impeller replaces Johnson/Evinrude OMC/BRP Part Number 5033542. This platform is now integrated and seamless.

part #: 188907 prices

• $54.00-$79.22

specifications ignitionstartin:

• for makes: Johnson, Evinrude
• brand: Sierra
• mpn: 18-8907
• part type: Impeller

offer ignitionstartin:

• quantity: 8
• options: Ship-to-home
• availability: In Stock
• started: June 7, 2026
• sold: 0

returns ignitionstartin:

• time: 30 Days
• policy: Returns Accepted
• paid by: Seller

payments ignitionstartin:

• wallet: Paypal
• other
• credit card: Mastercard

seller ignitionstartin:

• city: Wheeling, Illinois
• # reviews: 113176
• rating: 99.0%

shipping ignitionstartin:

• transit: 4-10 Days
• service: Economy
• class: Economy
• type: Fixed
• cost: $0.00

general ignitionstartin:

• Boat Parts > Inboard Engines Components > Ignition Starting Systems
• condition: New

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