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Engine & DrivetrainDiscussions about the engine and drivetrain of your vehicle.
This is a discussion thread titled "no mufflers - whos done it - hows it sound", within the Engine & Drivetrain forum, part of the Technical & Vehicle Assistance Forums category.
i am thinking of running my two oem cats, then dual 2" s.s. pipe, then x pipe then stright out dual side rear exits. ok ok i know what some of you are thinking - " way to loud " but hold on , my previous truck was a 99 silverado with a 5.3 liter v8 and it also had 2 factory cats -what i did with that truck was went from the 2 cats back into a y pipe ran for 6" single then ran back into a y pipe and dual exits-" no mufflers" it sounded awsome- 60's muscle car sound not to loud. so whos done this or anything like this to the tundra? any comments welcome but i dont want to hear -"that will be to loud from anyone whos never done anything like this- no ignorant comments please. thanks
i am thinking of running my two oem cats, then dual 2" s.s. pipe, then x pipe then stright out dual side rear exits. ok ok i know what some of you are thinking - " way to loud " but hold on , my previous truck was a 99 silverado with a 5.3 liter v8 and it also had 2 factory cats -what i did with that truck was went from the 2 cats back into a y pipe ran for 6" single then ran back into a y pipe and dual exits-" no mufflers" it sounded awsome- 60's muscle car sound not to loud. so whos done this or anything like this to the tundra? any comments welcome but i dont want to hear -"that will be to loud from anyone whos never done anything like this- no ignorant comments please. thanks
Do you really want to run afoul of emissions and sound limit laws? Better check in to that before you mod anything, man.
I did something similar with my 86' formula. I cut out the muffler and ran on just the single cat. I sounded real loud but in a good way. On that car it really improved the performance. I don't know how the Tundra would respond to almost no back preasure, and with the software in these trucks it may hurt.
Everybody where I work (except me) runs straight pipes from the cats on back and they sound pretty decent. One is a Dodge with 5.2 and single exhaust, another is a 350 Chev with duals. You can't beat the price! I also have a buddy that bought a 2000 Tundra used, about a year ago. He welded in a piece of straight pipe in place of the stock muffler. It sounds about like mine, and I've got about $900 invested in headers and a dual cat-back system.
__________________ ADDING POWER HAS NEVER BEEN SO FAST!
not to rain on anyones parade... but if/when you do that, be prepared for a large investment at your local dealerships service dept. the trucks are designed to run with a certain amount of backpressure... taking away that backpressure will screw up everything from sensors to the computer, which will cause air/fuel ratio problems (remember... controlled by the computer) which will eventually fubar your engine. unless your an ace mechanic, and/or have a seriously modified setup as it is now... i would ditch the idea all together. if you want a nice sound for cheap, go grab a dynomax exhaust.
its usually kids that i see doing this, purely because they want their engine to rattle the windows on my front door when cruising down the street. i just get a good laugh out of it... what they arent usually aware of, is it hurts their engines more than it helps. unless you have some massive 500 big block... its pointless.
i'm not sure about where you live, but i dont think i would want to go ripping apart my axhaust system once per year to throw in a muffler to pass emissions and inspection.
Well, after reading a few posts and some thought, (mis-guided as it may be), I'm thinking of doing a little of what you were thinking.
I'd like to put headers on, run with the stock pipes through the cats and then dual pipes out the rear from there. I'm not aware of anyone designing in "backpressure" from a muffler for proper operation? If its that sensitive to "backpressure", then using anything other than the Toyota muffler, (these advertised "free-flowing, better breathing"), would cause variation in backpressure, i.e. problems ? ! ? !
The flow of the exhaust is:
Out of head
Into Manifold
Past 1st O2 sensor
Through Cat's
Past 2nd O2 sensor
Though Muffler
Out the back
All you would be doing is eliminating the "Through the Muffler" portion. The flow past the emission devices is still the same. I think the sound would be awesome. Noisy? Nope, that's music when you hear V-8 duals. I had a similar set-up on a GMC full-size pick-up in the mid-90's. Granted it was before OBDII and dual O2 sensors etc. but it had dual cats and straight pipes out the back. It was a low tone sound which was not objectionable at all but "talked to you".
If you know for a fact why this would not work or cause problems with the Tundra, I would like to know.
Well, after reading a few posts and some thought, (mis-guided as it may be), I'm thinking of doing a little of what you were thinking.
I'd like to put headers on, run with the stock pipes through the cats and then dual pipes out the rear from there. I'm not aware of anyone designing in "backpressure" from a muffler for proper operation? If its that sensitive to "backpressure", then using anything other than the Toyota muffler, (these advertised "free-flowing, better breathing"), would cause variation in backpressure, i.e. problems ? ! ? !
The flow of the exhaust is:
Out of head
Into Manifold
Past 1st O2 sensor
Through Cat's
Past 2nd O2 sensor
Though Muffler
Out the back
All you would be doing is eliminating the "Through the Muffler" portion. The flow past the emission devices is still the same. I think the sound would be awesome. Noisy? Nope, that's music when you hear V-8 duals. I had a similar set-up on a GMC full-size pick-up in the mid-90's. Granted it was before OBDII and dual O2 sensors etc. but it had dual cats and straight pipes out the back. It was a low tone sound which was not objectionable at all but "talked to you".
If you know for a fact why this would not work or cause problems with the Tundra, I would like to know.
ok... allow me to give an answer with a little more detail.
you, for the most part... answered the question yourself. with dual o2 sensors, readings are taken at the back of the cat as well as the front... when there is no "backpressure", the flow is quick, and readings are seldomly correct. when these readings change, the computer tries to automatically adjust the fuel delivery, causing it to usually run too lean (or too rich in some instances)... which will in turn, will cause performance to decrease. run this for a substantial amount of time, and you could also be looking at some decent valve burning. in essence... you are slowly tearing apart your engine.
when changing out to a custom exhaust, you STILL have backpressure... unless the muffler is nothing more than a shell and straight pipe, there is enough to slow down flow for sensors to take accurate readings.
it is not as if the moment you do this, your engine will explode... hell... it may be months or years to see any effects from it. but the one effect that will be obvious almost immeditely, is the decrease in power. not knowing toyota backwards and forwards yet, i cant tell you how much that may be... might not even be noticeable... but it will drop.
all i am saying is, if you are an experienced enough mechanic to work around the problems that this would cause, then you are an experienced enough mechanic to know that there are better ways of accomplishing it.
you dont have to agree with me, and i could be off base, but every mechanic that has worked on our ihra team has given me this same info in the past at some point... and i trust them to know exactly what they are talking about.
O2 sensors simply produce a voltage output relative to the oxygen content of the "atmosphere" in which they are installed, (i.e. exhaust stream), ....no "back-pressure" required to do that.
If they are installed in a "pipe" that contains exhaust from the engine "bank" of cylinders, it will adequately "sample" the exhaust in the pipe for oxygen content regardless of "backpressure". The only thing that could screw that up is a leak in the "pipe" that would allow oxygen to enter into the "atmosphere", (i.e. exhaust stream), to throw off the oxygen content of the exhaust stream being measured.
One could debate the effect of this type of change until the end of time. I'll tell you what I'm going to do........ I've got a little over 35,000 miles on my truck. I'm going to make the change and I'll report here over time how many hundreds of thousands of trouble free miles I am able to achieve so those contemplating this change so the "voice" of the Tundra can be heard can make an economical choice to do so without fear of ruining their truck.
I will also monitor the output of the post-cat sensors to see what changes are seen when the changes are made; both pre and post change.
O2 sensors simply produce a voltage output relative to the oxygen content of the "atmosphere" in which they are installed, (i.e. exhaust stream), ....no "back-pressure" required to do that.
If they are installed in a "pipe" that contains exhaust from the engine "bank" of cylinders, it will adequately "sample" the exhaust in the pipe for oxygen content regardless of "backpressure". The only thing that could screw that up is a leak in the "pipe" that would allow oxygen to enter into the "atmosphere", (i.e. exhaust stream), to throw off the oxygen content of the exhaust stream being measured.
One could debate the effect of this type of change until the end of time. I'll tell you what I'm going to do........ I've got a little over 35,000 miles on my truck. I'm going to make the change and I'll report here over time how many hundreds of thousands of trouble free miles I am able to achieve so those contemplating this change so the "voice" of the Tundra can be heard can make an economical choice to do so without fear of ruining their truck.
I will also monitor the output of the post-cat sensors to see what changes are seen when the changes are made; both pre and post change.
so... you are saying that o2 sensors just reach out and grab the exhaust as it comes by, and pressure has nothing to do with it? isnt it the pressure that allows heat to build as it passes by, and dont o2 sensors need a warm up period, usually to somewhere between 600 and 700 degrees? how quickly is a pipe that is moving all heat and exhaust going to heat up? in the time it takes to warm the o2 sensor, your engine is burning incorrectly, as the o2 sensor reports an open state. and it all goes back to what i stated originally.. run long enough like that, and you are bound to eventually run into some problems.
i asked our mechanic this last night as a matter of fact, and his exact reply was: "have fun with your valves". when a guy that builds 800hp engines for a living tells me something, i am going to listen to him. do whatever you wish... but even if i didnt have him... the yearly emissions testing, and falling back to "the vehicle was not designed to do that" would rule it out in my book.
The hottest part of the exhaust system is the cats. The second set of O2 sensors sits behind the cats and once the cats are lit, they are HOT HOT HOT and so is the exhaust stream leaving them. Aside from that, our O2 sensors are heated by an internal heater until they are hot enough or warmed up by the exhaust stream.
No backpressure is required to "heat" the O2 sensor or to have it take accurate readings. If the engine is running, all that is "passing-by" the O2 sensor and through the pipe is the exhaust......and that exhaust is a continual stream being pumped out by the engine.
I believe the original question to the forum was did anybody "know" why this would not work. So far, there has been many reasons stated why this would not work based on "Dad said", "Mechanic said", and so on and so on. My thought, (as indicated by my responses), is that is will work, and I have stated why I believe that to be so. Once again, we could debate will or will not for a long time.
I am looking for practical experience with a Toyota Tundra. I guess nobody has tried it and therefore unable to report the results.
Running without a muffler will not affect the o2 reading. I have run straight pipes on Mustangs with the FAST ECU and the wide band o2 works properly. The o2 does not measure backpressure nor does it need backpressure to work.
Now if you ran open headers/manifolds you would more than likely have a problem with burnt valves.
With that being said I would still recommend putting a muffler on the Tundra or you are at risk of losing performance, specifically low end torque. These engines are not designed to run in the 6000+ rpm range where an open freeflowing exhaust would be more helpful. There are all types of mufflers out there for the sound you are looking for.
well i asked for no ignorant responses and i guess a couple of you couldnt help yourself - if youve never run exhaust without a muffler why would you even ring in on this subject? WHY!!? a few of you guys obviously know what your talking about- like i said to start with ive already done this on a silverado 99' with a 5.3 liter v8 and no problems ,added power ,and as a matter a fact- everyone gave me compliments and it sounded stock sitting at idle so for you ignorant ones plz stick to what you know and dont speculate on $hit you have no idea on and for the guys who have some good cold hard facts - thank you for the input men.
no mufflers - whos done it - hows it sound
Better check in to that before you mod anything, man.
- justin