I just do not get what purpose it fits. Also, how is the valve activated? Any delay from wot to open?

 

not off hand, but i've experienced this with my brother's supra. For TC'd engines, it doesnt really matter that much, and you want as free flowing exhaust as possible. see the thing is. backpressure helps with the low end torque. if you eliminate it you make more room for air to flow freely, which gives you higher top end power. At higher RPM's torque is less of a factor, but for off the line power you need some backpressure for the torque, which is why there is a valve in there.

 

So instantly if installing a new exhaust system that say had a 5 ftlb torque increase but didn't have the valve would equate to the stock exhaust with the valve as far as low end torque?

(ignore the numbers, they are not important)

 

they dont make the car good but they are needed from a toyota standpoint. I would personally keep the valve if there is one. Most of the new BMW's have them on their dual exhaust, yahama bikes have them and a little bit of back pressure is good and would help with the scavenging effect I would think...

 

technical explaination of the valve. from a different car, so the numbers might be slightly off, but the concept is the same

A mechanical valve in the rear muffler varies muffler volume to help enhance engine power in different speed ranges. At lower engine speeds (around-town driving, for example), the valve remains closed to provide a smaller-volume muffler chamber. The resulting level of exhaust back-pressure enhances power at these speeds. When exhaust pressure reaches about 22 psi -- which occurs at about 2,400 rpm -- the valve opens to allow exhaust gas through an additional chamber. The resulting increased muffler volume reduces exhaust back-pressure, enhancing power at higher speeds. Muffler valve operation does not affect the noise level.

 

The VW R32 has the same type of valve too.

 

The Nissan Altima also has it on their 2.5 engine it's in the brochure explaining what it's for

 

The engine in the Scion tC has been around in one form or another as a car and truck powerplant for many years, continuously improved for power, torque, and Toyota levels of quietness and reliability. It comes with electronic variable valve timing for good low end torque development, and twin balance shafts for smoothness. Tuned to 160 horsepower and 163 foot-pounds of torque, the engine is quiet, smooth, and plenty powerful in a 2900-pound car, and at full throttle, it sounds powerful without being intrusive, because it has a valved muffler that opens up at high rpm and can be worth as much as 5 horsepower.

This quote is curtsey of NCTD

Hopefully. This answers anybody’s question about removing the valve.

 

Congratulations, its a muffler valve!!!!




After days of cutting wheels and freaking double wrapped metal, I was able to get in and prove that there is indeed a muffler valve. Apparently it opens when the pressure builds up(In chamber 1 and 2) and more flow is needed. :D This concludes the 2page long debate on the tC muffler valve.

 

Holy crap that muffler looks very restrictive!! :? hmm so many baffles. After seeing that im sure even an exleback should yield some gains.

 

think of your valve prob this way. where do the noise police live? where do they listen? I the sound reducing valve was removed your car would make more noise at low speeds, and you could get pulled over for just crusing around town doing nothing. Is the hassle worth it?

 

mmm..I don't think removing the valve would cause any more noise. The car already has two catalytic converters and a resinator. Heck the axle back from us is pretty dam quiet as it is too. :D