How Do Compound Turbos Work? | Compound Turbochargers Explained
Posted by Will on Oct 17, 2025
How Do Compound Turbos Work? | Compound Turbochargers Explained
On a 5.9L or 6.7L Cummins, a compound (twin) turbo pairs a small high-pressure turbo with a larger low-pressure turbo. The small turbo spools fast for low-RPM torque, then the large turbo supplies airflow at higher RPM. Working in series, they deliver smooth boost across the range, cut EGTs, and improve towing, power, and drivability.
Ever wondered how compound turbos actually work and why they’re so effective at keeping EGTs in check? This post walks through the basics and links to our in-depth video. Whether you daily drive, tow, or want reliable power, a Diesel Power Source compound setup can make your Cummins feel stronger and cooler under load.
Watch: Compound Turbos Explained
Video Summary
We answer the common questions: what is a compound turbo and why do twin turbos lower EGTs so well? The video shows how a DPS Compound Turbo Kit routes air from the larger low-pressure turbo into the smaller high-pressure turbo to deliver dense, efficient airflow. The result is strong low-end spool, clean top-end power, and cooler exhaust temps. If you run a 5.9L or 6.7L Cummins and fight high EGTs while towing, this is for you.
How Compound (Twin) Turbos Work
- Low-pressure stage: The larger turbo draws in ambient air and compresses it moderately.
- High-pressure stage: That pre-compressed air feeds the smaller turbo, which adds a second stage of compression.
- Result: Higher mass airflow at lower shaft speeds, strong boost from down low through the top end, and reduced heat per unit of boost, which helps lower EGTs.
Why It Helps on Cummins Trucks
- Lower EGTs under load: More efficient compression and airflow keep temps in check while towing or climbing.
- Stronger low-RPM response: Quick spool from the small turbo improves drivability.
- Top-end airflow: The large turbo sustains boost and power at higher RPM.
- Broad, usable powerband: Smooth boost across the range for daily use and heavy work.
Who Should Consider Compounds?
If you tow regularly, see high EGTs, or want reliable power without giving up street manners, a compound kit for a 5.9L or 6.7L Cummins is a smart option. It’s also a strong path if you plan future fueling upgrades and want headroom without excessive lag.
Ready to Explore Kits?
Browse our DPS Compound Turbo Kits. Each kit is engineered for cooler EGTs, smooth drivability, and dependable power on Cummins-powered trucks.
Next step: Find the right compound kit for your build and towing needs. See kits.
