And read this: "In addition, a variable backpressure exhaust system is installed to boost low-down torque and top-end power."
And then: "The V6 engine has fabricated stainless-steel exhaust headers and a variable backpressure valve in the main muffler. The exhaust valve opens steplessly according to backpressure.
This reduces noise at low engine revolutions and reduces backpressure at higher rpm for improved performance."
This sounds really cool, but I don't quite understand how it works.
Any one heard of this? Is this system installed on US Camrys as well?
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Last edited by Chris Corolla S; 07-18-2003 at 12:44 PM.
Yes most of the Toyota VVTi's have somehting like this. I know our echo has a flapper on a spring in its muffler that opens under higher flow to straighten the path of the air. Simple but it works.
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O ok so it's just a flapper in the muffler? I was thinking they were saying something about a real valve... I guess I have one too then rezzle. I hava a 2001 VVT-i 1ZZ-FE... I'll poke at my muffler tonight...
ive seen systems like this before where they basically use a butterfly valve in the exhaust pipe controlled by selinoid type thing that is controlled by the pressure in the intake, pretty simple but they have problems with the butterfly valve getting stuck do to heat and corsion, its basically an imbred version of the vtec system, but since its further back in the exhaust it isnt as good maybe if u could build 4 of them that didnt corode and could stand high heat and put them on each runner of a header.................
it can be just a reed valve that opens up when you floor the car. its not hard to do. My pal has a variable volume muffler in his car, its nice, quiet at normal revs, but gets somewhat louder at higher revs.
yeah, its kinda like the same concept of some of these newer aftermarket exhaust systems where they have "plates" that are placed in the exhaust system to increse/or/reduce backpressure and gives a louder/or/quieter tone depending upon the number of plates used... ya' know what I am talking bout Chris?
yeah, its kinda like the same concept of some of these newer aftermarket exhaust systems where they have "plates" that are placed in the exhaust system to increse/or/reduce backpressure and gives a louder/or/quieter tone depending upon the number of plates used
UMM, nope its not. THe one you're describing is a supertrapp style resonator, which is basically a simple straight through design that works basically on the same prinicple as a silencer of a firearm. The one I'm talking about is a normal muffler with a valve that opens to allow the exhaust to choose a faster route out of the system at wot, hence the term variable volume/flow.
UMM, nope its not. THe one you're describing is a supertrapp style resonator, which is basically a simple straight through design that works basically on the same prinicple as a silencer of a firearm. The one I'm talking about is a normal muffler with a valve that opens to allow the exhaust to choose a faster route out of the system at wot, hence the term variable volume/flow.
Ohhhh, OK, I got ya... my bad... I feel stewpid now!
UMM, nope its not. THe one you're describing is a supertrapp style resonator, which is basically a simple straight through design that works basically on the same prinicple as a silencer of a firearm. The one I'm talking about is a normal muffler with a valve that opens to allow the exhaust to choose a faster route out of the system at wot, hence the term variable volume/flow.
Ahhhh....I was thinking about doing something along those lines w/ my Camaro when I build it, like maybe a y-pipe before the muffler and after the headers w/ some kind of solenoid switch so I could run open headers @ the flip of a switch....while still being street legal
they have systems like that but keep in mind that its going to be put threw alot of water corosion rust high heat rapid temperture changes and things of the such, something that would be cool would be to un hook the parking break and use the cable to hook it up to a buterfly valve on a straight pipe type system so ya it would be cooler then crap, pull the "parking break" and bam open header
Ahhhh....I was thinking about doing something along those lines w/ my Camaro when I build it, like maybe a y-pipe before the muffler and after the headers w/ some kind of solenoid switch so I could run open headers @ the flip of a switch....while still being street legal
Yes those are called "Dumps" they have been popular with muscle car dudes for years... Although I think it is totally irresponsible to run an open exhaust.
It is a great theory and I bet it works, but not for long. given the nature of exhaust (hot, corrosive gasses, humidity etc) I would say stay away from moving parts in the exhaust stream. For 'a' race it might work, but for the cut and thrust of day to day driving it will be little more than an expense.
The best H.P. gains are made upstream while the exhaust is hot from the exhaust manifold. Because of the heat, the volume is greatest and potential to reduce back pressure is more effective at this point. Large 'fart can' exhaust have a diminished effect, being downstream, and exist more to make noise. Throw the heat early in the exhaust stream and therefore reduce the volume downstream. Really!
Well, I'm sure the variable back pressure mufflers work because both Nissan (Altima 2.5 and Maxima) and BMW (3 series) have them on their mufflers. They are restrictive under low revs and and they open a flap at higher revs and temps to let the exhaust out faster. You can't really see it on the Nissans, but the next time you're behind a new BMW 3 series, try to look up it's tail pipe while at a stoplight and you'll see a flap blocking one of the two muffler tips. Depending on the driver of the car, you might be able to see the flap open as the driver accelerates from a stop, or you'll see it open as the BMW gets into the higher speeds.
btw, it's easiest to see the BMW flap at night because your headlights shine right into them, and even easier if your car is lowered.
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variable backpressure exhaust system!?
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