aeronautica86

Anyone know?

962 kid

980

W8MM

Correct. See the upside-down part number below:

JS

I just found this thread, I was wondering the same.

IcemanG17

What do the exhaust vacuums do?

W8MM

They are activated by the ECU at various engine loads and speeds, according to which gear is selected, to change some gas-flow path lengths inside the muffler. The vacuum motors supply the force to move the internal flaps. The result is more engine output and a great sound at high engine speeds.

IcemanG17

Thats what I thought.....It just seems that vacuum actuators near a hot muffler will not last that long? But corvettes use them too?

Woodster

Audi uses the same thing on the new RS4 !!

I have heard it sounds like an old V-8 muscle car ??

I have not "heard the car" , I have only seen it, but if Porsche and Audi use it
IT WORKS !!

Marty k

W8MM

The motors, IIRC, are of all-metal construction. If they use a metallic bellows connected to a push rod, there are no sliding parts to bind up at temperature extremes, or with a little corrosion.

Also, bending a springy metal, which ordinarily has an essentially uniform spring constant over a wide variety of temperatures, means that the actuation force is stable and repeatable. As long as the control-hose material can stand muffler area temperatures, there is no obvious reliability problem or predictable failure mechanism.

Using vacuum (variable pressure air!) as a force-transfer medium dispenses with flammable fluids that would be required with a hydraulic method.

Seems ideal to me

tridente78

Another pic that confirms 980 is right.