I-Noise Reduction Device History

A wall of I-NRDs

The I-NRD Wall - A few of the many versions of the Iannetti designed I-NRD

The biggest challenge we have encountered to date while working with the Wankel type rotary engine has been the development of an efficient, long lasting sound attenuation device for racing which is compact and lightweight with little or no detrimental effects on the performance of the engine.

To our knowledge, the I-Noise Reduction Device (I-NRD) is unmatched in its level of thermal, mechanical, acoustical and packaging performance when compared to any of the alternative solutions tested to date for the high performance motorsports environment.

The high exhaust temperatures exhibited by a high performance Mazda rotary engine, particularly when gasoline is used as the fuel, has made it extremely difficult to suppress the exhaust noise without the aid of a large and heavy muffler which, at times, can be power-restrictive as well as display elevated outer surface temperatures.  In many instances, the outer skin of these mufflers can be nearly as hot as the exhaust headers.

The exhaust headers in a racing Mazda rotary engine using gasoline can reach temperatures as high as 1,850F (1,010C) for normally aspirated applications, and up to 1,900+F (1,038C) in forced induction engines.  In comparison, the maximum temperatures observed in a reciprocating piston engine with a similar power output and same fuel type is 1,375F (746C) for normally aspirated engines and 1,500F (815C) for forced induction engines.

There have been a multitude of organizations and individuals who have invested a considerable amount of time and resources to develop a noise attenuation system for the Wankel rotary engine.  None of these efforts have accomplished the level of performance attained by the I-NRD.

Some of these organizations and individuals include the major auto and engine manufacturers, past and present, who have worked with the Wankel type rotary engine such as Mercedes Benz, Mazda, General Motors and Curtis Wright. Also, several major companies specializing in exhaust systems for passenger and performance vehicles and thousands of small and large motorsports teams the world over have struggled with this challenge.

History of the I-NRD

I-Rotary manufactured and tested thousands of concepts, prototypes and models to address this challenge. The efforts to develop the I-NRD began in 1985.  A brief history of the evolution process for the I-NRD can be found in the links below:

I-NRD Home
Team Highball IMSA RX-7 GTU 1985