Over the last couple of decades, as the turbocharger revolution has taken place within the motorsports community, one topic which is often discussed is turbocharger system configuration and design. We’ve all seen the internet memes with horrific welding, atrocious tubing layout, and wastegate placement nowhere near optimized. I’ve struck up a solid friendship with Marty Staggs of Turbosmart USA, and after attending a recent event where I saw a wide variety of wastegate setups, I was curious about what’s best for performance. So I asked him, and decided that I probably wasn’t the only person who was curious about system layout and figured I’d share the answer to my One Question with all of you.
When designing/building a turbo system, what do you recommend the builder do with respect to wastegate placement?
Marty Staggs, Turbosmart USA: A wastegate is a device that controls the flow of exhaust gas from the engine to the turbocharger. It is basically an exhaust gas regulator. By controlling the flow of exhaust gas to the turbine of the turbocharger, the wastegate can then control the boost pressure provided by the turbocharger to the engine.
The better the flow of exhaust gas to the wastegate, the better it is able to bypass and control the flow of exhaust gasses driving the turbine. So basically, by controlling the exhaust gas flow to the turbo, we can regulate the shaft speed of the turbo and the by-product of this shaft speed control, is boost control.
The ideal location for the wastegate is as close to the turbine housing as possible, and in a manner that provides a good flow path into the wastegate. If this is not possible, the next best location is at (or just after) the exhaust collector and again, in a manner that provides good flow into the wastegate.
I say that with the assumption that the gate is properly sized and controlled. Now if you have a small motor and install a Powergate 60 with only a 7 psi spring, in a way that the exhaust goes straight at the gate, and you want 30psi of boost, you’re going to have problems. Also, a gate mounted on the side of a pipe at a 90 just plain sucks. You will really have to get the turbine size right or it will also have problems. This will require a larger gate than normal. More often than not, experience is the best guide when it comes to wastegate sizing and placement.
Thanks to Marty for taking time out of his busy schedule to answer our question! Check out previous installments of One Question content right here.