Choosing the Right Turbo for Your Diesel Engine
When replacing or upgrading the turbo on your diesel engine, size is a crucial factor. Yes, size does matter, but not in the way you might think. Bigger isn't always better, and with so many options available, it can be confusing to choose the right turbo.
For race engines, the answer is straightforward: get the largest turbo you can spool or the biggest allowed by the rules. For street trucks, the decision is more complex because drivability is a major consideration—no one wants to wait at a traffic light while their turbo spools up.
Certain Cummins and Power Stroke engines can support over 400 rear-wheel horsepower with a stock turbocharger, while Duramax engines can handle around 500 horsepower. For power outputs between 500 and 800 horsepower or for heavy towing, consider upgrading.
Turbo size is measured in millimeters, indicating the compressor wheel’s inducer diameter and the turbine wheel’s exducer diameter. The turbine-side housing ratio (A/R) also affects turbo behavior. A smaller housing can create high drive pressures, while a larger housing can cause turbo lag.
Consulting experts like Cameron Lewis of KC Turbos can help. They consider factors like injector size, turbo size, fuel/oil system upgrades, daily use, towing frequency, elevation, power goals, and budget to recommend the right turbo.
A larger turbo might experience severe turbo lag and not spool until the engine reaches 2,200 to 2,500 rpm. If you have performance upgrades like a high-performance camshaft and enough fuel, a turbo that spools above 2,500 rpm might not be an issue.
At KC Turbos, we tow heavy loads. If you tow over 10,000 pounds, a bigger turbo might be a good option as it helps regulate higher Exhaust Gas Temperatures (EGTs). While spool-up might be slower, the benefit of EGT reduction is significant.
A turbocharger of a given size will behave differently on different engines. For instance, a 7.3-liter Power Stroke produces more exhaust gases due to its larger displacement, which means more energy to drive the turbocharger at lower RPMs.
Choosing the right turbo involves balancing size, engine modifications, and driving habits. Always consult with experts to ensure you get the best performance and drivability from your turbo upgrade. Be honest with your turbo manufacturer about how you use your truck and its current parts to make the best decision.
For a more detailed guide, read the full article at Diesel Army.