But think about this: If the air can’t get into the turbocharger or the exhaust can’t get out of the engine effortlessly, how is a larger turbocharger going to make more turbo boost?
In reality, you must make the semi-truck run “free” – with better air and exhaust flow – to gain additional fuel mileage, performance and longevity from the engine.
Start by changing out the stock muffler for a performance muffler, which will allow the engine to gain ¼ mpg or more.
Also consider dual exhaust: It will outperform a single stack, help air flow through an engine better and lower the exhaust gas temperature by about 50 degrees.
Next, look at the air intake system. Two air filters mounted outside of the hood are much better for air flow than one air filter under the hood.
Aerodynamic trucks all have the air filter under the hood, so we have to work with it. I recommend installing the Fleet-Air Filter, which is made of three layers of foam sprayed with oil over an aluminum frame. This filter is designed to enhance air flow to the turbocharger, and the engine will gain another ¼ mpg as a result.
-Bruce Mallinson is the owner of Pittsburgh Power, an engine performance shop in Saxonburg, Pa.