Cummins Turbocharger Buying Tips: Match, Brand & Power​

Introduction

Selecting the right turbocharger for a Cummins diesel engine is critical for maximizing performance, efficiency, and longevity. Whether for a heavy-duty truck, industrial equipment, or high-performance build, the turbocharger must be carefully matched to the engine’s airflow requirements, intended use case, and supporting modifications. This guide explores key factors in turbo selection, including compressor and turbine matching, brand comparisons, and performance trade-offs specific to Cummins applications.

I. Turbocharger Matching for Cummins Engines

Cummins engines (such as the 5.9L 12V/24V, 6.7L ISB, and larger industrial variants) have distinct airflow characteristics that influence turbo selection. Proper matching ensures optimal boost response, fuel efficiency, and reliability.

1. Engine Displacement & Airflow Requirements

• 5.9L Cummins (12V/24V):

• Naturally aspirated versions require turbos with quick spool characteristics (e.g., HX35, HX40).

• Modified engines (500+ HP) need larger turbos (S300/S400 series) or compounds.

• 6.7L ISB:

• Factory turbos (Holset HE351VE, VGT models) balance efficiency and response.

• High-power builds (600+ HP) benefit from BorgWarner SXE or Garrett GTX turbos.

• Industrial/HD applications:

• Larger displacement engines (QSL9, X15) require turbos with high flow capacity (Holset HX50, HX60).

2. Compressor & Turbine Selection

A. Compressor Side Considerations

• Target Boost Pressure:

• Street builds (30-40 psi) need efficient mid-range compressors (e.g., 60-68mm inducer).

• Race applications (50+ psi) require larger wheels (72mm+) for high airflow.

• Compressor Maps:

• Plot engine airflow (lbs/min) against pressure ratio (PR) to ensure operation within 70%+ efficiency islands.

• Example: A 600HP 5.9L Cummins needs ~65-70 lbs/min at 40 psi (PR ~3.7).

B. Turbine Side Considerations

• Turbine Housing A/R Ratio:

• Low A/R (0.7-1.0): Faster spool, better low-end torque (ideal for towing).

• High A/R (1.1-1.5): Reduced backpressure, better top-end power (racing).

• Turbine Wheel Design:

• Standard (cast): Cost-effective, durable for most applications.

• Billet/GTX: Lighter, faster response (high-performance builds).

3. Single vs. Compound Turbocharging

• Single Turbo:

• Simpler setup, easier tuning. Best for 400-700HP street builds.

• Example: BorgWarner S364.5SXE (5.9L/6.7L).

• Compound Turbo (Sequential):

• Small turbo (high-pressure) spools quickly; large turbo (low-pressure) provides top-end flow.

• Ideal for 700+ HP (e.g., S362/S480 combo).

II. Turbocharger Brands for Cummins Engines

1. Holset (Cummins'OEM Supplier)

• Pros: Reliable, cost-effective, optimized for Cummins engines.

• Models:

• HX35/40: Classic 5.9L turbos (300-500HP).

• HE351VE (VGT): 6.7L factory turbo (good for 400-500HP tuned).

• HX50/HX60: Heavy-duty applications (800+ HP).

• Best For: Stock rebuilds, mild performance upgrades.

2. BorgWarner (S300/S400 SXE Series)

• Pros: Ball-bearing options, robust construction, excellent compressor maps.

• Models:

• S364.5SXE: Ideal for 500-650HP 5.9L/6.7L.

• S467.7SXE: Supports 700+ HP (6.7L high-power builds).

• Best For: High-performance street & towing applications.

3. Garrett (GT & G Series)

• Pros: Advanced aerodynamics, billet compressor wheels (GTX).

• Models:

• GT3788R: Balanced 5.9L/6.7L performance (500-600HP).

• GTX4294R: Extreme airflow (800+ HP).

• Best For: Maximum efficiency in high-boost applications.

4. Precision Turbo (PTE)

• Pros: High horsepower capability, durable journal bearings.

• Models:

• PTE6266: 600-700HP range.

• PTE6870: 800+ HP drag builds.

• Best For: All-out racing (less focus on daily drivability).

5. Industrial Turbo Brands (KKK, Schwitzer)

• Pros: Heavy-duty construction for industrial Cummins engines.

• Best For: Mining, marine, and generator applications.

III. Performance Considerations & Trade-Offs

1. Boost Response vs. Peak Power

• Quick Spool (Towing/Daily Driving):

• Smaller turbo (HX35, S362SXE).

• Lower A/R housing (0.8-1.0).

• High Peak Power (Drag Racing):

• Larger turbo (S480, GTX4202R).

• Higher A/R (1.2-1.5) for reduced backpressure.

2. Heat Management & Durability

• Turbo Cooling:

• Water-cooled CHRA (critical for extended heavy loads).

• Ceramic-coated turbine housings reduce under-hood temps.

• Oil Supply Requirements:

• High-flow oil feed (0.065” restrictor for ball-bearing turbos).

• Synthetic oil recommended for high-EGT applications.

3. Supporting Modifications

• Fuel System:

• 100+ HP injectors require upgraded CP3/HPFP.

• Exhaust & Intake:

• 4”+ downpipe, free-flowing intake (e.g., S&B).

• Tuning Considerations:

• Custom tuning (EFI Live, Smarty) to optimize VGT actuation or wastegate control.

Conclusion: Selecting the Best Turbo for Your Cummins

• Stock/Mild Upgrades: Holset HE351VE or HX35.

• 500-700HP Street/Towing: BorgWarner S364.5SXE.

• 700+ HP Racing/Drag: Compound turbos (S362/S480) or GTX4294R.

• Industrial Use: Holset HX50/60 or KKK turbos.

Always match the turbo to your engine's airflow needs, intended usage, and supporting mods. Investing in a properly sized, high-quality turbo ensures optimal performance and longevity for your Cummins diesel.