Someone has mentioned that tC has a valve in the muffler that opens at higher rpms allowing for less backpressure (read: better flow). IS there any way to get that thing out of there compeletely? Why would I need that in my muffler at any rpms??????

Let me know,

Thanks

TOYOTA :evil:

I believe it is supposed to help retain low rpm torque. At higher rpms the backpressure is reduced allowing a little more flow for high end horsepower.

Of course I may be totally wrong. ;)

I know the new Z06 Vette has one, but I never heard that about the tC :?

yes...the tC has one......and unless you're changing the muffler....don't take it out....you'll lose low end power.....any car needs backpressure for performance...otherwise they wouldn't have put it in there...as rpm's change...obviously so does the amount of exhaust being expelled...that's why it opens more and more as your rpms rise..

yes...the tC has one......and unless you're changing the muffler....don't take it out....you'll lose low end power.....any car needs backpressure for performance...otherwise they wouldn't have put it in there...as rpm's change...obviously so does the amount of exhaust being expelled...that's why it opens more and more as your rpms rise..

I am not entirely convinced. I do not believe that the engine needs so much bakcpressure that it warrants a valve in the muffler. The backpressure is already there; mufflers, piping and cathalytic converter provide plenty of backpressure to the engine. So much that it makes sense to eliminate some with high quality/high flow sport exhaust we can see outher (does TRD exhuast incorporates a valve in the muffler, too??)
On the other hand, I do believe some backpressure is factored into the design of the engine/exhaust system and necessary for proper operation, I just do not believe it is so much that it warrants the valve. I would rather believe that this is Toyota's own attempt to comply with emissions/noise regulations and all these VLEV specs out there...
Anybody has any thoughts? Any words of wisdom from the tuners?

Thanks in advance...

The valve is to keep it quiet. Nothing more. THe chance of getting it out without ruining the muffler are pretty much nil.
If you want your car to be louder, just get a different muffler.

The valve is to keep it quiet. Nothing more. THe chance of getting it out without ruining the muffler are pretty much nil.
If you want your car to be louder, just get a different muffler.

And why would I want the car louder??? :)
My only concern is that the valve decreses the flow which is never good......
Is there any way to disable it so it stays open all the time?

The valve is to keep it quiet. Nothing more. THe chance of getting it out without ruining the muffler are pretty much nil.
If you want your car to be louder, just get a different muffler.

And why would I want the car louder??? :)
My only concern is that the valve decreses the flow which is never good......
Is there any way to disable it so it stays open all the time?

the valve is wide open at WOT. you have nothing to worry about.

ok, ok I will see if I have an extra tC muffler lieing around and cut the sucker in half. I already did it with the xA/xB Muffler and dam there were a lot of baffles, but I would like to see whats inside the tC muffler. :twisted: I will check the back stock room later today. :)

the A's and B's ahve 'em too so don't worry about it your not alone ;) :D

there are no muffler valves in the xA or the xB muffler. I have physical proof of that. I actually cut an xB muffler in half to see what was inside. nothing but baffles, but no valves.

ok, ok I will see if I have an extra tC muffler lieing around and cut the sucker in half. I already did it with the xA/xB Muffler and dam there were a lot of baffles, but I would like to see whats inside the tC muffler. :twisted: I will check the back stock room later today. :)


Stylis,

Let me know what you found and if there is any way to get thing out of there....


Thanks

heehee, monster garage ain't got nothing on me. :twisted:

yamaha first made the butterfly exhaust valve for their sport bikes. Toyota doesn't design or make their own engines anymore, it's all designed by yamaha hence why we have exhaust butterfly valves. BMW 330's have them too when you sit behind one in traffic look at the exhaust with your headlights on. You'll see it on the left or right tip.

Back pressure gives you torque, when you gas it it opens allowing free flowing exhaust gas to exit. Don't mess with it, if it was bad or served no purpose they wouldn't put it into the car.

yamaha first made the butterfly exhaust valve for their sport bikes. Toyota doesn't design or make their own engines anymore, it's all designed by yamaha hence why we have exhaust butterfly valves. BMW 330's have them too when you sit behind one in traffic look at the exhaust with your headlights on. You'll see it on the left or right tip.

Back pressure gives you torque, when you gas it it opens allowing free flowing exhaust gas to exit. Don't mess with it, if it was bad or served no purpose they wouldn't put it into the car.

deamonite,
Thanks for the info. I am not sure though that everything that the maker pust in the car is 'good'. Some of the features serve only the purpose of complying with endless regulations and limiting liability (warranty) (electronic speed limiter etc. etc)
For now I ma going to leave it as it is but I ma not going to agree with the statment that "if it is there it is needed" for the reasons stated above.

Cheers,

there are no muffler valves in the xA or the xB muffler. I have physical proof of that. I actually cut an xB muffler in half to see what was inside. nothing but baffles, but no valves.

Stylis... You sound like a good guy to have on the board? Where do you work at? Pardon my ignorance.

Does the valve in the tC's muffler have anything to do with the VVT-i?

there are no muffler valves in the xA or the xB muffler. I have physical proof of that. I actually cut an xB muffler in half to see what was inside. nothing but baffles, but no valves.

Stylis... You sound like a good guy to have on the board? Where do you work at? Pardon my ignorance.

Does the valve in the tC's muffler have anything to do with the VVT-i?

Hi Somnambulated,
I work at Precision Muffler & Brake in Milpitas,Califorrnia. AKA(The Scion Central) www.precisionmuffler.com I have yet to cut the tC muffler open, I have been very busy at teh shop, but I will crack it open on monday. Not a lot of work that day so I will have my digital camera ready. :D

geez. dyno your car. then put headers, highflow cat, 3" pipes all the way back and a valveless muffler and tell me what your low end torque does.....IT GOES DOWN. Why? you eliminated your backpressure.

its for low end torque, if you dont want low end torque, by all means, get rid of the valve.

geez. dyno your car. then put headers, highflow cat, 3" pipes all the way back and a valveless muffler and tell me what your low end torque does.....IT GOES DOWN. Why? you eliminated your backpressure.

its for low end torque, if you dont want low end torque, by all means, get rid of the valve.

Geez,
Since you seem to know the answer do you have the dyno results that support it?

Thanks,

the valve is open at WOT. are you worried about losing power at half throttle? i don't get it.

the valve is open at WOT. are you worried about losing power at half throttle? i don't get it.

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

geez. dyno your car. then put headers, highflow cat, 3" pipes all the way back and a valveless muffler and tell me what your low end torque does.....IT GOES DOWN. Why? you eliminated your backpressure.

its for low end torque, if you dont want low end torque, by all means, get rid of the valve.

Geez,
Since you seem to know the answer do you have the dyno results that support it?

Thanks,


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)

yamaha first made the butterfly exhaust valve for their sport bikes. Toyota doesn't design or make their own engines anymore, it's all designed by yamaha hence why we have exhaust butterfly valves. BMW 330's have them too when you sit behind one in traffic look at the exhaust with your headlights on. You'll see it on the left or right tip.

Back pressure gives you torque, when you gas it it opens allowing free flowing exhaust gas to exit. Don't mess with it, if it was bad or served no purpose they wouldn't put it into the car.

deamonite,
Thanks for the info. I am not sure though that everything that the maker pust in the car is 'good'. Some of the features serve only the purpose of complying with endless regulations and limiting liability (warranty) (electronic speed limiter etc. etc)
For now I ma going to leave it as it is but I ma not going to agree with the statment that "if it is there it is needed" for the reasons stated above.

Cheers,

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.
:blah: :no:

Congratulations, its a muffler valve!!!! :P
http://www.precisionmuffler.com/4441a940.jpg
http://www.precisionmuffler.com/4461b940.jpg
http://www.precisionmuffler.com/44880e00.jpg

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. 8)

Holy crap that muffler looks very restrictive!! :? :shock: 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