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Sounds Like Teen Spirit

Although turbocharging can improve engine performance, there is a drawback.

Although turbocharging can improve engine performance, there is a drawback. When the driver gets his or her foot into the accelerator, the sound of the turbo isn’t exactly exhilarating. MANN+HUMMEL (www.mann-hummel.com; Portage, MI) has engineered a solution along with help from DaimlerChrysler and Ford of Europe. A simple solution. It’s called the “symposer.” Basically, the device is a thermoplastic-based assembly that is fitted in front of the throttle body. There are four chambers inside of it. There are two chambers on the engine side and two on the outlet side with a pivoted flap in between. Engine-generated pulsations from the air intake go into the chamber which oscillate the flap, thereby transferring into the outlet chambers. Then, in turn, the pulsations go into a sound pipe that sends the engine noise, which now sounds more powerful, into the cabin of the vehicle. Note that this sound isn’t emitted to the outside. According to Claude Mathieu, president and CEO of MANN+HUMMEL USA, the company was initially looking at active noise control technology but determined that it would be an exceedingly expensive approach to accomplishing this noise enhancement. The first application is on the Ford (European) Focus ST and it is scheduled to be used on two forthcoming North American turbo applications, one in ’08 and the other in ’09.

Another development from the company—this with significantly greater applicability than just hot-sounding turbocharged cars—is a cylinder head cover made of recycled materials. The first application is on the Volkswagen VR6 3.2-liter and 3.6-liter FSI engines. It is produced with polyamide fibers from carpet, both over-produced fibers (75%) and waste (25%). This is in lieu of the conventional glass-filled Polyamide 66. Not only is this more environmentally correct from the standpoint of recycling, but the surface quality of the molded component tends to be better than that made with the virgin material. What’s more—and probably more important in some regards—given the rise in resin prices, the recompounded material is less expensive.—GSV