In this video, we take an in-depth look at one of the most debated matchups in the VP44 Cummins community: the HY35 vs HX35 turbocharger. Both of these factory turbos came on 24-valve Cummins trucks between 1998 and 2002, but they have very different reputations when it comes to performance, boost control, and overall drivability. This is a full dyno comparison to see how each turbo actually performs in a real-world scenario—not just forum speculation.
We start with a baseline dyno pull using the stock HY35 and see what kind of boost and torque it makes out of the box. From there, we tighten up the wastegate to push the HY35 as far as we realistically can while still being safe for a street or tow rig. After that, we swap on a bone-stock HX35 from a VP truck and repeat the same test with factory settings. Finally, we install a boost elbow to crank up the gate on the HX35 to match the HY35 and see how they compare apples to apples.
Throughout the video, we show detailed dyno graphs and data including horsepower, torque, peak boost pressure, drive pressure, and EGTs. We also explain how each turbo reacts under load, how the gate settings affect performance, and what kind of gains you can realistically expect if you’re considering a swap or adjustment. The results show clear differences not just in power, but also in how the engine responds and how usable that power is on the street or while towing.
This is the kind of test that diesel truck owners have been asking for—real numbers, real setups, and real answers. If you’re building a VP44 truck and want to know whether it’s worth modifying your HY35, upgrading to an HX35, or saving your money for a bigger charger down the road, this is a must-watch. We’re using this test as a baseline for our 500 horsepower VP44 street build, and in future videos, we’ll be installing performance injectors and testing more aggressive turbo setups.
Let us know in the comments what you want to see next. Should we add injectors to this setup first and see how far the stock HX35 can go? Or should we bolt on one of our 60/64 or 69mm chargers with stock injectors and push airflow to the limit? Make sure to like, comment, and subscribe to stay up to date with our full series on VP44 Cummins upgrades, dyno testing, and real-world diesel performance results.
Power Driven Diesel is a specialty performance shop engaged in the engineering and development of high-performance turbo diesel technologies.
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