RA was asked by one of its large OE Customers to develop a concept Titanium exhaust system for a new high performance Sports Saloon with 6 cylinder turbocharged engine for Launch in June 2014.

Scope:

Complete “cold end” exhaust system. Two Electronically controlled exhaust valves, switchable by the driver. In the first mode the exhaust to meet European Drive-by standards (70/157/EEC) with a “sporty aggressive sound”, progressive with engine speed. In the second mode or “track mode” the exhaust must produce a sound “ as loud and aggressive as possible”. In both modes there should be no “unpleasant frequencies” or “booms”.

Key Inputs (from Customer):

  • 1 x Prototype Vehicle
  • CAD data for existing steel exhaust system
  • Tailpipe noise frequency analysis data for steel exhaust system
  • ECE drive-by noise data for steel exhaust system

Key outputs (from RA):

  • Prototype exhaust system for demonstration
  • Supporting development documentation (acoustic, temperature, backpressure)
  • Complete CAD model in Catia V5 with detailed drawings for competitive quotation

Timing:

  • 4 weeks – 3 weeks with vehicle

Project Detail:

RA analysed the CAD data from the existing steel exhaust system and the tailpipe noise frequency analysis to predict potential physical and acoustic design constraints. In discussion with the customer, these were clarified and a more detailed acoustic target was established.

RA used its suite of in-house acoustic development tools to determine the required muffler volume, tailpipe length, absorption and resonator package in support of the project targets. Understanding the differences in acoustic properties between stainless steel and Titanium, enabled RA to design, develop and build a prototype assembly jig and an initial stainless steel prototype system with configurable sections and internal components. This modular system approach not only saved valuable development time with the vehicle, but considerably reduced overall costs.

Following a number of iterations to achieve the desired interior and exterior subjective level and quality, a prototype Titanium system was built incorporating all aspects of the final design and instrumentation for temperature and backpressure measurement. This was built using the latest high temperature specification Ti alloy, capable of withstanding the temperatures <800C. Critical temperature and pressure data was obtained at high speed on the test track.

Vehicle noise data was recorded both statically and dynamically at full load in a semi-anechoic chamber. Data from both the tailpipe and the driver and passengers head position, was processed to produce a frequency analysis including engine order data and “waterfall” charts. This data was compared to the baseline exhaust data and the predicted results. The excellent correlation enabled an accurate prediction of an ECE drive-by noise result, thus saving time and cost.

Finally the complete system was presented to the Customer at our Development Centre in Daventry UK, along with complete supporting documentation and design detail. This was subsequently presented internally at the Customer site to wide acclaim.

Titanium Exhaust System Development

Project Outcome:

  • Titanium exhaust system produced
  • Exceptional sound quality and refinement achieved in both operating modes
  • Delivered within 4 weeks
  • Delighted Customer
  • Product Launch June 2014

It’s incredible! Your exhaust is famous in our company!

satisfied customer