The Cat C15 Acert, a powerful diesel engine known for its 625 hp output, often undergoes single turbo conversions. Originally designed with a compound turbo system to meet stringent emission standards, many owners opt for a single turbo setup for various reasons, including simplicity, cooler operating temperatures, and cost-effectiveness in the long run. This article delves into the reasons behind this popular modification, the process involved, and the advantages and disadvantages of switching to a single turbo configuration.
Why Convert to a Single Turbo?
Simplified Engine Bay and Maintenance
One primary reason for the conversion is simplification. The compound turbo system, while efficient, involves complex plumbing and two turbochargers. A single turbo setup streamlines the engine bay, reducing potential boost leaks and simplifying maintenance. This reduction in complexity makes the engine easier to work on and diagnose problems. The image below illustrates the significant space gained with a single turbo.
Cooler EGT and Improved Fuel Efficiency
Another compelling reason is the potential for cooler exhaust gas temperatures (EGTs) and improved fuel economy. With a properly sized single turbo and corresponding ECM tuning, the Cat C15 Acert can run cooler and more efficiently. This cooler operation, coupled with optimized fueling, often translates to better fuel mileage.
Long-Term Cost Savings
While the initial investment for a single turbo conversion can be significant, it can lead to long-term cost savings. Replacing or repairing the factory compound turbo system is expensive. A single, readily available BorgWarner S400-based turbo offers a more affordable and easily replaceable alternative.
Reduced Engine Stress and Head Gasket Protection
Compound turbo systems, by design, multiply boost and drive pressure. While manageable at stock power levels, increased horsepower significantly elevates these pressures, potentially damaging the head gasket. A single turbo, when properly sized, minimizes these pressures, reducing stress on the engine and protecting the head gasket.
Single Turbo Conversion Components
A comprehensive single turbo conversion kit typically includes a new exhaust manifold, downpipe, oil lines, air cleaner piping, charge air cooler piping, and the turbocharger itself. The image below showcases a complete kit from Momentum Worx.
Turbocharger Selection for the Cat C15 Acert
The BorgWarner S430 series is the popular choice for single turbo conversions on the Cat C15 Acert. These turbos can efficiently support power outputs ranging from 425 to 600 hp.
Performance Options for Higher Horsepower
For those seeking higher horsepower, upgraded S430 turbos with titanium compressor wheels or larger 80mm compressor wheels are available, capable of supporting over 750 hp.
Compression Ratio Considerations
Lowering the compression ratio is not always necessary for a single turbo conversion. Stock compression ratios are often sufficient for moderate power increases. However, for significant power gains, lower compression pistons are recommended to prevent head gasket issues.
ECM Tuning: Essential for Optimal Performance
Proper ECM tuning is crucial for maximizing the benefits of a single turbo conversion. Optimized tuning ensures smooth drivability, minimizes turbo lag, improves fuel efficiency, and unlocks the full potential of the new setup.
The Case for Retaining the Compound Turbo System
While single turbo conversions are popular, the factory compound turbo system, when properly tuned, offers excellent performance and broad power delivery. For those prioritizing drivability and moderate power levels, retaining the compound setup with ECM tuning is a viable option.
Ultimately, the decision to convert to a single turbo depends on individual needs and priorities. Factors to consider include desired horsepower, budget, maintenance preferences, and driving style.
