Inconel 625 racing exhaust system produced with
metal additive manufacturing

Manufacturing exhaust systems for high performance racing cars is an exact science. In particular, designing each system so that the flow of exhaust gasses is precisely controlled, to minimise back-pressure, optimise scavenging effects and maximise engine power and throttle response.

Most standard production cars use cast exhaust manifolds or headers. By comparison, performance cars, especially race cars, generally use lightweight and custom engineered exhaust headers and pipes. These are normally produced from tubes that are bent or swaged together; although this is an established method of manufacture it often leads to compromises in terms of the number of individual parts required and the nature of the exhaust gas flow.

Additive manufacturing reduces number of parts and improves gas flow
Our customer wanted to optimise the performance of a V6 engine with a custom design of exhaust header. As the nature of the application meant that the header assembly would be subject to extremely high temperatures the material chosen was Inconel 625.

By working closely with our customer, we were able to develop a custom header design suitable for 3D printing using our metal additive manufacturing system. This had a number of important advantages:

• Optimised exhaust configuration to improve the gas flow
• Each design was produced in two sections, which reduced the number of parts by 60%, compared with the traditional method of manufacture
• Minimising the number of parts and assembly operations also removed 5 welds per header assembly, effectively reducing potential points of failure by around 80%.

The exhaust header parts were printed simultaneously in sets, then were wire EDM cut from the base platform before final CNC machining to ensure the headers fitted precisely to each engine block without the risk of gas leaks.