No doubt you’ve probably noticed those diesel pick up trucks driving around your town with the huge 5″ exhaust pipe sticking out the back and wondered…”what’s up with those huge exhaust pipes, is that just some fad for looks and noise?” Well, you might be surprised to hear that there’s more than just look and noise behind big exhaust on turbo diesels.
Because of the way turbochargers work, they are actually more efficient with a bigger exhaust. Honestly, the best exhaust for a turbo engine is no exhaust at all! The reason has to do with back pressure, basically you want a lot of pressure going into the turbo (from the burned fuel) and little or no pressure on the other side of the turbo. When you have that condition you get a more efficient turbo system which leads to faster spool up leading to the bottom line: more power, sooner. What could be better right? Well, how about better fuel economy? Yup, a more efficient system also leads to better fuel economy – when you don’t have your foot to the floor that is!
So the next time you see a Duramax or Cummins next to you at the light with a 5″ pipe you can turn to your buddy and tell him all about back pressure and turbo exhaust systems and you’ll look like the genius, have fun!