muffler placement

[nwmod39]

how far back from the headers should my mufflers be placed. the flowmasters on my k-20 are near the back axle. to me it sounds like the exhaut is some what tingy. it almost sounds like pinging or spark knock under power but still has a ting sound to it at idle.

thanks
steve

[84slopwaggin]

That's the characteristic of a Flowmaster. You could step up and run magnaflows. They are straight through designs unlike Flowmasters that are full of tin.

[piecesparts]

I am here to tell you, that UNLESS you get the TOP dollar stainless steel Magnaflow, you will replace it in a two year period of time. I put a magnaflow on my 91 and two years later it had holes in the back of it, I replaced it wih another Magnaflow and YEP you guessed it two years later I had to replace it due to holes. I drive the doggy out of my truck and I get tired of doing the muffler thing, so I now have a Flowmaster on it to see if it stands up longer. On that truck it is 3" single inlet with two 2 1/2" outlets. I easily put 21,000 miles on a year, so I keep the pipes warmed up and cleaned out. I live in the country and do mostly highway driving.

[nwmod39]

it is making it tough to try and set the timing and adjust the advance curve.
not sure what line of flowmaster it is but i do not like it.
what is the ideal location to put your mufflers?
i was thinking of getting a new dual exhaust system with an x pipe and some new mufflers so i guess the exhaust shop will have more input.
thanks
steve

[84slopwaggin]

I have flowmaster myself and I heard that magnaflows flow better, because of the straight through design. Piecespart what are your takes on which sound better in your opinion? I love how flowmasters sound, although I am going to try another set of Hooker Areo Chambers.

Are you using a timing light to set the timing? The sound of flowmasters should have no effect on setting the timing.

[nwmod39]

yes i use a light for my timing. what i am trying to do is recurve the advance on my distributor and i am really not able to hear if the timing and curve that i have in it are aloowing the engine to ping. all i can hear is the exhaust.

[84slopwaggin]

Oh I see. If you listen closely you will be able to distinguish between the two. You shouldn't have to change location of you muffler for fine tuning. You haven't stated where the exhaust exits the truck. I know if they dump before the axle you will hear a deep drone sound in the cab. If yours are like this then you should definitely be able to distinguish between the two sounds. If it exits the rear then you will just have to listen really carefully and put a heavy load on the engine when driving.

[nwmod39]

exits out the side of box behind the rear wheels.
i have tried to go up some hills and put some load on it and it sounds like a ping but like i stated before, even when it idles in park and i crawl under it i can hear the ping/tinny sound.
as for the muffler placement, i was thinking that the mufflers were placed to far back, near the rear axle now, and maybe the long length of pipe before the muffler was where the sound was coming from.
thanks
steve

[nwmod39]

forgot to add

timing is set at 8 degrees now with the advance curve starting just a tad above 800 and all in my 2800.

[piecesparts]

The sound of the Magnaflow was a subtle mellow tone. It is a good mix of sound and performance. I put a flowmaster 50 series 3" in and dual 2 1/2" out on the 91 that I just took the magnaflow off of. It gave me a hollow throaty sound and I believe that I am happier with the Flowmaster sound over the Magnaflow. I agree that the straight through design should give more Hp, but the pack steel pack muffler design is like the old style glass pack mufflers and the little ribs will give a distortion to the laminar layers of exhaust flow, I am not convinced that that is better than the Flowmaster design. I think that distortion will cause a wave reversion back into the exhaust and rob Horsepower. My 91 appears to accelerate better after the change.

I have flowmaster 40 2 1/2" series mufflers on my 84 show truck and the 383 is really loud and hollow (Love it with the cam I have), but it does get in your way if you are trying to get a hint of spark detonation.

[84slopwaggin]

Piecesparts where do your exhaust exit on the 84? I'm addicted all future projects will be dumped before the rear axle. Next I will be using a set of Hooker Areo Chambers.

[piecesparts]

I have my exhaust exiting at the rear of my truck. Any time I had exhaust dump out the side, either before or after the rear wheel, the noise levels were too high in the cab. With the exhaust coming out the rear, the noise is carried away from the driver. I have sliding back window glass in my trucks and I run with them open a lot, during the summer.

[tgh117]

Regardless of what brand you want to talk about, mine are located just behind the transfer case. I have two flowmaster 50 series, before that had 40 series for 10 years in the PA salt. Never had a problem with the mufflers, had the pipes replaced twice. First pipes came out the side, then the second came out the back. Couldn't hear it in the truck enough, so now them come out the side again behind the rear tires. Good luck iwht your mufflers. You can attach the back of the muffler to the crossmember that runs right under the back of the cab. Makes it realy easy to install and hold up under there.

[Bishops Trucks]

I have 40 series Flowmasters on my 3 trucks and all are located right behind the cab and exit at the bumper. (striaght out the back) I have echo can tips on them and they all sound great. They are all through 2 1/2" pipe = 2 with 3 1/2" cans and one with 4" and an H-pipe. I haven't had any problems with them or tuning the truck and I get loads of compliments on the sound.

[Chevrolet4x4s]

Do the echo can tips really make that much of a difference in the sound?
Thanks
Shane



ooh yeah my glasspacks are located right infront of the rear axle and exit behind rear wheels to the side.

[Chevrolet4x4s]

OOH YEAH ......I forgot to ask does anyone know of a replacement latch for the rear sliding window?
Thanks
Shane

[Bishops Trucks]

They produce (in my opinion) a hollow sound. An exhaust system is like a musical horn. Sounds change and vary depending on the bends and routing of the pipes. A system with an "X" or "H" pipe will sound differant than a dual system that is independant of each side. The independant setup gives to differant tones and the joined setup is even in sound.

[piecesparts]

The exhaust system can be tuned for sound, but one should think of the performance aspects of it, more. The "X" pipe produces a significantly better torque curve on the motor than an "H" pipe, but they are "BOTH" better than having two seperate exhaust pipes on a vehicle. The idea of the exhaust pulses from one cylinder pulling the gases from another cylinder is good for power building. I am presently running an "H" pipe and it is at the rear end of my tranny tube on a 700 R4 and then I have exhaust run all of the way to the rear of the truck through the Flowmasters (at thefront edge of the bed) with "MEGS" stainless steel oval tips on the 2 1/2" pipes. The sound is stron, hollow, and loud enough to cause undue stress on Mr. Johnny Law.

The sound of the exhaust changed when I put the 383 stroker motor in the truck with the different cam profile. The overlap made the exhaust louder than it was before. So what do "echo can tips" do for you, besides make your truck sound different? I have a town full of "buzz bug" Oriental cars with coffee can mufflers and nothing up front to make it go. My Flowmasters run them off.

[84slopwaggin]

Hey now you leave those poor RICEHEADS alone. You big meanie

[396C20]

Originally Posted by nwmod39

how far back from the headers should my mufflers be placed. the flowmasters on my k-20 are near the back axle. to me it sounds like the exhaut is some what tingy. it almost sounds like pinging or spark knock under power but still has a ting sound to it at idle.

thanks
steve

Generally, I think you want to place the muffler as far away from the header as possible. I have seen some drag cars with the muffler right at the rear bumper. Not that it is visually appealing or logistically possible for all vehicles. I don't know what the science is behind that but I have read it in numerous articles. Just my 2 cents.

[piecesparts]

I disagree with the placement of the muffler as far away as possible. I would support that the mufflers should be within a short distance from the crossover pipe ("X" or "H" design). I would go with the headers discharging into the crossover tube and then the muffler being within 12 to 18 inches after that. The mufflers at the rear end will defintitely cause what was reported as a tingiy sound and even affect performance some. The gases of an exhaust are constantly cooling as it exits the engine and as it gets close to the taile end of the vehicle, it is relatively cold compared to the exhaust from the motor. This cooling causes a vacuum effect on the exhaust system and helps it to pull the exhaust from the cylinders of the engine. When you place the mufflers at the rear, there will be a change in the flow of the gases at that point and it will cause the exhaust to get lazy in it's effect. With the mufflers further forward, it is still warm and is still in the full effect of the cooling/vacuum change and thus creating a better flow through the muffler and exhaust pipe. (This will also keep the muffler from rusting more)

In the early years FORD (God I really hated to use that word) had the exhausts on their Galaxy and Fairlane cars where the muffler was at the rear and it really sucked. The drag cars that "396C20" referred to have actually very little muffler and the pipes are usually large. There are things such as "Supertrapp" units that are nothing more than a set of plates mounted over the exhaust flow, like an old 2 stroke dirt bike muffler. These are only at the very end of the pipe and they are not very efficient. I agree, they look like "Crap".
I would give Flowmaster a call on their tech line and ask them what would be the best setup and where things should be. Ask as if you were looking to do a system using their stuff and they will talk your ear off about it. When I built my 84 GMC stroker motor, they gave me a lot of data as to what size pipes and what mufflers to use. It has served me well since.

By the way---Are there any Rice Specialists in the house?

[boxrodz]

pieces-
I've heard and read where some would run a line of paint on the exhaust pipes starting near the headers and extending down along the pipe a ways. Then they would run the engine until it reaches the normal operating temperature, then check to see at what location where the paint is not burned off. That's what they use to determine where to place the 'X' or 'H' pipe. Maybe, the muffler could be placed beyond this 'heat' zone.

[piecesparts]

That is not a bad idea, the crossover pipe area should be right about the end of your tranny and the mufflers should be relatively close to that, being next in line. The thought process that I have learned, is to get the mufflers at a spot that they are still involved in the excavation of exhaust gases from the headers. The motor depends on this process, so that the cylinders will clean themselves and fill with clean fresh fuel laiden air.

[84slopwaggin]

No rice specialist here, but I think alot of the late model vehicles have the muffler alot closer to the rear(vettes, firebirds, camaro). I suppose when you use a cat it changes everything.

[piecesparts]

The only reason that most of those have the muffler at the rear is that there is virtually no room for it anywhere else. Take into account the actual length of the vehicle and the fact that the exhaust runs a dual into single and then sometimes back to a dual. This is very inefficient, but you make do with what you have. However, one can build on this and make a great system. The proper design will build a large amount of HP and give you a decent sound.