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Navigating the T4 Non-Wastegated Turbo Trend

Posted by Diesel Power Source on May 12, 2016

Are They Worth It?: 

In the dynamic world of diesel pickup modifications, one trend has gained significant traction – the use of T4 non-wastegate turbos as an alternative to stock upgrades. With their seemingly attractive price point, often ranging from $500 to $800, compared to the typical $1500-$2000 price tag, these T4 turbos have become a tempting option for enthusiasts seeking enhanced performance. However, as with any cost-saving measure, the question arises: Are T4 non-wastegated turbos truly worth the investment? 

Understanding the T4 Non-Wastegated Turbo: 

It's crucial to recognize that T4 turbos are originally designed for OEM purposes, catering to small industrial engines or gasoline cars with lower RPM needs. These turbos lack external wastegates, making them more budget-friendly but sacrificing certain performance aspects that diesel truck drivers often prioritize, such as quick spool-up, high top air flow, and high pressure ratios. 

Hidden Costs and Adaptations: 

While the initial cost of T4 turbos may be lower, there are hidden expenses associated with their use. T4 housings were not crafted to fit seamlessly into Dodge Cummins engines, requiring adaptations to the intake, exhaust pipe, exhaust manifold, and intercooler tubing. Even after these modifications, you're left with a turbo lacking a performance-bearing structure. While T4 turbos are reliable, they do not feature a 360-degree thrust bearing or grooved journal bearings necessary for high-speed applications. 

Spool-Up and Drivability Concerns: 

One significant drawback of T4 non-wastegated turbos is their high A/R ratio, typically around 0.9 or higher. This results in slow spool-up times, compromising bottom-end performance and overall drivability. While the top-end performance may be acceptable, the sacrifice on the lower end can impact the overall driving experience. 

The Value of a Wastegate: 

Wastegated housings come at a higher price, but the investment is justified by the added benefits of variable geometry. A wastegate allows a smaller turbine housing to function as a larger one by efficiently bypassing exhaust, providing a 10-15% increase in flow without sacrificing spool-up. This dynamic capability distinguishes wastegated turbos as a superior choice for those seeking optimal performance. 

Making an Informed Decision: 

Before succumbing to the allure of a big, inexpensive T4 turbo, it's essential to consider the implications. If you value quick spool-up, drivability, and overall performance, a T4 non-wastegated turbo may not be the ideal solution. Consulting with experts, asking the right questions, and understanding the sacrifices involved will help you make an informed decision, ensuring your diesel pickup retains its greatness without any buyer's remorse. 


While the T4 non-wastegated turbo trend may seem enticing initially, it's crucial to weigh the costs, adaptations, and compromises associated with these turbos. A careful evaluation of your priorities and performance expectations will guide you towards making a decision that aligns with the true value you seek for your beloved truck.