Killing a Duramax: pt 12 – Unclog the clog!

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Sometimes you hit a design wall, and no matter what tricks you try, no matter what tuning tricks you do, you’ve either met or exceeded the design limitations of a part.

Not a single component of the mighty Duramax L5P in the Banks video series “Killing a Duramax” has yet to succumb to the riggers of what Gale and the crew have thrown at it. Parts have been changed out for higher-performing components, such as upgraded fuel components and the turbocharger. See, even though the stock turbo has long since been replaced by a high-flowing unit from Precision 76/75 helping the engine reach 852 horsepower getting the exhaust to spin, the turbo’s assembly has been effectively chocked by the stock turbine inlet piping, pedestal, and turbine outlet. These parts not only cause an exhaust restriction but also elevate exhaust pumping restrictions and add heat.

To get the turbo working more efficiently, the exhaust system needs an enema! To remedy this and get the turbo spinning to its full potential engineers have removed and replaced the stock 2.25” manifold outlet pipes with 3” and replaced the stock pedestal with a fabricated high-flow collector. This new turbine inlet flow combined with a 5” turbine outlet unclogged the clog, and without any other changes, Gale and the crew hammered the throttle getting 912 hp, proving that you can make sizable horsepower increases with the proper piping. 

Next up, a new Comp Cam should help this engine hit 1,000 horsepower.