Best Size Choices for a Holset He561v and He400v Compound Turbo System to Reach 850 Hp

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When it comes to maximizing performance in diesel engines, the Holset HE561V and HE400V compound turbo system is a popular choice among enthusiasts looking to reach 850 horsepower. Selecting the right size for each turbo is crucial for achieving optimal efficiency and power output. This article explores the best size choices for these turbos.

Understanding Compound Turbo Systems

A compound turbo system utilizes two turbos in sequence to achieve higher boost levels and improved performance. The smaller turbo (in this case, the HE400V) is typically used to spool quickly at lower RPMs, while the larger turbo (HE561V) takes over at higher RPMs, allowing for greater airflow and power.

Choosing the Right Size for HE561V

The Holset HE561V is designed for high-performance applications and can support significant horsepower. When selecting the right size for the HE561V, consider the following:

  • Compressor Wheel Size: A larger compressor wheel will enable the turbo to flow more air, which is essential for reaching 850 HP.
  • AR Ratio: The turbine housing’s A/R (area to radius) ratio affects spool time and top-end power. A balance between quick spool and peak performance is key.

For the HE561V, a compressor wheel size of around 66mm is often recommended for applications targeting 850 HP. A turbine housing with an A/R ratio of 0.80 to 0.90 provides a good balance between spool time and top-end power.

Choosing the Right Size for HE400V

The HE400V serves as the smaller turbo in the compound setup, and its size is equally important for achieving desired performance. Here are some considerations:

  • Compressor Wheel Size: A smaller compressor wheel helps with quicker spool times, which is essential for low-end torque.
  • Turbine Housing Size: The size of the turbine housing affects how quickly the turbo can react to exhaust flow.

For the HE400V, a compressor wheel size of around 56mm is typically recommended. A turbine housing with an A/R ratio of 0.70 to 0.80 will provide the necessary response for low-end power while still allowing for decent top-end performance.

Boost Levels and Tuning Considerations

Once the turbos are selected, achieving 850 HP will also depend on proper tuning and boost management. Here are some key points to consider:

  • Boost Pressure: Aim for a combined boost pressure of around 50-60 PSI for optimal performance.
  • Fuel Delivery: Ensure that the fuel system can support the increased demand for fuel at higher boost levels.
  • ECU Tuning: A custom tune is necessary to optimize fuel maps and timing for the compound turbo setup.

Common Challenges and Solutions

While the Holset HE561V and HE400V compound turbo system can yield impressive results, several challenges may arise during installation and tuning:

  • Spool Time: If the larger turbo spools too late, consider adjusting the A/R ratio or using a smaller turbine housing.
  • Boost Control: An external wastegate may be necessary to manage boost levels effectively.
  • Heat Management: Proper intercooling is essential to maintain performance and engine health.

Conclusion

Selecting the right sizes for the Holset HE561V and HE400V turbos is critical for achieving 850 HP in a compound turbo setup. By following the recommendations outlined in this article, enthusiasts can optimize their performance and enjoy the benefits of a well-tuned compound turbo system.