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Big Rig Exhaust System, Help Needed


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OK guys, here's one that'll probably make you laugh.

Do the big diesels have mufflers hooked up?

I've seen YouTube vids of big rigs with "straight pipes", are these w/o mufflers?

I'm with the exhaust pipes on my project, and the kit pipes on a 359 don't appear to have mufflers. 

Can I add fat stacks and have no mufflers for a custom truck?

Edited by 10thumbs
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It all depends Michael, there are some of the larger diameter pipes that do have mufflers hidden in them, but most are just as the videos say....straight pipes! 

As for your project, unless I find your build thread before you answer :lol:, which 359 are you working on, is it the AMT or the Revell Snap with the little sleeper or the Revell of Germany glue kit with the larger sleeper? The only one I'm not familiar with is the AMT, but I know both the Revell kits do have regular mufflered stacks, and looking at the AMT's California Hauler instructions, the lower part of their stacks are also the mufflers. 

As for your question about adding fat stacks and not running mufflers for a custom, YES!!!! Neither of these customs are going to have mufflers and are going to be running big stacks!

Ford with 8" stacks

Kenworth K100 with 10" stacks!

 

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Hi Matthew, thanks for the info, I read you loud and clear.  Read, no mufflers on my project.  It gets 10" stacks too.

edit:

PS: Those fat stacks on the last pic look right!

Edited by 10thumbs
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PS: Those fat stacks on the last pic look right!

Thanks Michael, they are from Rhino's Custom Model Truck Parts, his curved tipped stacks with elbows. I asked him to custom bend these ones with the elbows to the front of the truck instead of having the elbows facing the frame the way he normally bends the elbows. I am also going to have him make a set of air intake pipes for the air cleaners so all the stacks match, but they will be only about a 5 or 6 inch pipe. 

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Thanks for the info Matthew.  I'm a big fan of a little real metal on our models, those pipes will make for an outstanding build.

I worked a little last night on the exhaust system, the pipes from the motor out to the back are done.  Next the elbows on up to the big fat stacks.  Also, some trial glossy polishing of the aluminum stacks....oh yeah, they're cookin' now!

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The one thing that you have to keep in mind is that it is your model, so build it however you want.  Just have fun doing it to please yourself.

Thanks for the insight.

I'll try and remember.

Just the way I want my model to be, is fairly similar to the way it is in real.   Hence, my query here.  I don't have a clue about about mufflers on big rig Diesel motors.  I asked, now I have a real idea about the way it is.  The good part is, I don't have to build a muffler. 

Hey, mufflers suck when you want to run straight pipes.

Straight pipes it is.

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I always wondered the same thing, do the straight pipes have muffler somewhere on the way? And is it legal to go without a muffler at all? 

Bill Signs model has also sort of straight pipes even though the lower part is bent. But there´s a little tubing section of slightly bigger diameter under the frame, which I considered to be a silencer. That might be just another possibility for the straight pipes.

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Hi Jarda, I've seen those too.  I even thought about making those, but there's not much room underneath.

Here my project, these pics are new.  The 1st exhaust segment;

 photo -IMG_0816_zps2rpclfij.jpg

Jarda, I think you mean this, marked in red;

 photo -IMG_0816b_zpsia7dsvq7.jpg

I've seen pics where just a somewhat larger pipe is positioned there.   Actually, there is room, for simplification, maybe I'll do without them.

NEW QUESTION:

Guys, with big stacks, like 10"ers , how, or where do they meet the smaller 5" standard pipes coming from the motor?

I checked out some shops with aftermarket custom parts, and they offer a funnel shaped reducer-elbow.  I think I've seen too, that the smaller 5" pipes just seem to run up into the fatter stack pipes, without an elbow making the union of the two different sized pipes.

Any thoughts, or even pics?

Here the size difference on my project;

Left the scale 5" pipes, right the fat, scale 10" stack;

 photo -IMG_0817_zpscfkuzecz.jpg

 

So, I think I've seen the 5" pipes just bent upwards (with elbows) then the 10" stack just slipped over, no funnel or elbow attached.  Am I right?

How would you do it?  Does there have to be a "perfect and closed" connection for the two different sizes, or can they be just so that one runs into the other?

Whatcha think?

 

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Pipe reducers are as close as your desk drawer, the end of a cheap ink pen, cut off where u need it. They have to fit together tight or u have one heck of an exhaust leak!  I do my stack bends on a heavy sheet metal break, gives a much more realistic bend. Still have to sand and polish these.A lot of trucks use under cab mufflers, ck out berubes.com or iowa 80.com in the exhaust section.

DSCF0914.JPG

DSCF0912.JPG

DSCF0470.JPG

DSCF0911.JPG

DSCF0913.JPG

Edited by signguy2108
kenworth pic not suppose to be here
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Thanks Larry, good idea with the pen used as an elbow.

Just still not sure if they're needed.  Exhaust leak....well, straight pipes without mufflers, so maybe the smaller just feeds into the larger without being connected?

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OK, I found this:

 photo -fat stacks 2_zpseojoswoe.jpg

After checking all my pics a little closer, it seems most custom rigs have the fat stacks going right down under the cab, then probably joined with the smaller pipes just outside the frame rails.  If they were joined inside the frame rails, they'd probably hang down too low.  I imagine then, make a bend with the 10" stacks right up to the frame rails, then run the 5" pipes just to the outside of the frame rails, and join them right there under the cab.

Since mine has cab skirts, this will have to be a tight endeavor. 

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Thanks Larry, good idea with the pen used as an elbow.

Just still not sure if they're needed.  Exhaust leak....well, straight pipes without mufflers, so maybe the smaller just feeds into the larger without being connected?

I'm sorry, thought I was helping, guess not! And the pen is not used for an elbow, just a reducer between the stack and the elbow., and u still cannot just slide a 8-10" pipe over a 5"  and call it done, half of the exhaust (and smoke) will come out of the bottom!

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OK, I found this:

 photo -fat stacks 2_zpseojoswoe.jpg

After checking all my pics a little closer, it seems most custom rigs have the fat stacks going right down under the cab, then probably joined with the smaller pipes just outside the frame rails.  If they were joined inside the frame rails, they'd probably hang down too low.  I imagine then, make a bend with the 10" stacks right up to the frame rails, then run the 5" pipes just to the outside of the frame rails, and join them right there under the cab.

Since mine has cab skirts, this will have to be a tight endeavor.

Now you've got it! Also key word CUSTOM TRUCKS. Alot of them with the big stacks are show trucks that u don't have to listen to roar all day, hence the phrase "limited bobtail", "limited working truck"

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Thanks again Larry. 

I have a problem though.  I can't get the bend done properly on the big stacks.  The radius is just too long.

I found in my desk drawer though a pen that'll work great as a reducer.  Great tip!

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Here's a pic of the tube bending problem.  Left is a 5" tube, right the 10" tube.  5 cuts on the smaller tube gets a 90° bend.  7 cuts on the right, and only 45°. 

 photo -IMG_0819_zpsezzktm2c.jpg

I have a long way to go, and a learning process coming up.

Something else has to be figured out.

EDIT:

It just hit me.  I need to visit a real mechanic.  Brake lines.  They need to be bent too.  10mm tube is larger than usual brake lines, but maybe the tool used can be adjusted?

Edited by 10thumbs
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Thin wall aluminum tubing is incredibly hard to bend sharply, get some 6//8 or 7/16 inch stainless steel tubing that is 1/16 wall and use a real tubing bender or a wooden buck to bend them. You can use a grinder to thin the open end to scale thickness once you get the bends made and polish to your desired finish.

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tube benders won't bend a tighter radius than what is pictured in the kw cabover image. what you see at the bottom of the stack is what you get. anything tighter will crimp the tubing.

Ken is right, and that is why the ones on my KW seem to drop so low, because they will be low! 

OK, I found this:

 photo -fat stacks 2_zpseojoswoe.jpg

After checking all my pics a little closer, it seems most custom rigs have the fat stacks going right down under the cab, then probably joined with the smaller pipes just outside the frame rails.  If they were joined inside the frame rails, they'd probably hang down too low.  I imagine then, make a bend with the 10" stacks right up to the frame rails, then run the 5" pipes just to the outside of the frame rails, and join them right there under the cab.

Since mine has cab skirts, this will have to be a tight endeavor. 

 

Now you've got it! Also key word CUSTOM TRUCKS. Alot of them with the big stacks are show trucks that u don't have to listen to roar all day, hence the phrase "limited bobtail", "limited working truck"

And as Larry said, the key word is CUSTOM! There are some big pipes coming out with the reducers like in the pic that do come out under the cab

but there are also some that like my KW will be have to worry about speed bumps! :lol:

And though I didn't get a very good pic of it (yes these are mine from the 2012 Walcott Trucker's Jamboree :D) this truck looks like even the 45 angles you have would work because it looks like these pipes might be coming from underneath with a 45 then a short section into another 45 at the bottom of the heat shield. 

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Thanks guys.  Larry and Brian, that sounds interesting.  Matthew, thanks for the pics and the idea.  I'll be looking at two 45° pipes.

After thinking this over I came up with this.  First of all, this is 8mm tube, not 10. This was a quickie too.  It might have possibilities;

 photo -IMG_0820_zpsr6sria13.jpg

 photo -IMG_0821_zpswgq7onwj.jpg

The straight cuts like previously done with smaller tubes is the wrong way to go.  The cuts have to be crossed, like this;

 photo -IMG_0822_zpscgnfijfe.jpg

This was a quick job just to get a view at the results.  Take more time and make better cuts that go exactly halfway through and this might just work.  I'll try again soon.  I like so far, it's a progression.

Another thing I'm looking at is just having the elbow visible under the stack that runs straight down.  No bend on the fat stack, just bend the smaller tube and let the funnel be visible.

More later.

 

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Ok Michael, I'll put my 2 cents in on this.

 

With the Monster Stacks, there's a few different ways they are done. The way they are made is in 3 pieces, the elbow, the barrel and the tip. 

Let's start from the beginning, at the turbo. Diesel exhaust is typically 5 inch. There will be a piece, with a flare that will match up with the turbo and get V-clamped. On a Peterbilt, it have an elbow that will drop it down a few inches lower than the bottom of the frame rail. Some exhaust, will have pieces of flex pipe with mounts that go to a Y, then more flex to the lower elbow, that is at the bottom of the cab, which attach the muffler or barrel, then the tip.

Custom exhaust, some basically stock, 5 inch replacments from the lower elbow up. 

Then you got the same thing in 6, 7, 8 and 10 inches.

The Pickett brothers are making some very nice exhaust elbows. These drop the elbow down to the bottom of the step, there are a few pics already posted. They make them in different diameters. These boys also make Y-pipe, that is also in the different sizes, with a short barrel section that goes to the bottom of the turbo lower elbow. So for example, you can have, basically, from the turbo out, 7 inch exhaust.

Then there the reduced elbows like what has been posted already. 

Then there also the guys who run dummy stacks. There have weed burner exhaust, but have stacks. It seems kinda stupid to do it, but burner your arms a few times on hot stainless pipes and you'd understand, I know, I've done it myself.

Now, where that short barrel section is(which is behind the passenger side step), there can be a small, muffler put there. 

On the retro fit trucks, that's where they put the DPF, if someone is wanting there truck to not look like it's been retroed. Believe when I say there have been some, WOW, DPF retro installs out here.

Talk about mufflers. Dynaflex makes a custom, giant stainless, glass pack lookin muffler for trucks. The ends are reduced with muffler part being 7 inch round. They are the same length as the stock muffler. 

The last pic that Matt posted, the end dump, is a newer 389. That exhaust is stock. It's basically the same stock setup, but behind the heats held is just a thick piece of 5 inch, stainless pipe to reduced 7 inch, double wall and vented clean air tip. When I say double wall, I mean the 5 inch clamp area has another pipe inside that extend up into the 7 inch area about 6 8 inches. 

Hope this helps in your truck building.

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Thanks Clayton, I'm thinking now the 10" is just not feasible.  8" is a little easier to work with, and the reduction to 5", which is already coming from the motor is easier.

Just one part is still a big problem, the elbow on the 8" pipes.  I made a new one, it's better than the pics shown above, but still has a few crimps.

Next I'm trying a funnel to act as a reducer, and make this from real thin brass sheet.  This way it can be soldered, then it'll just get a shot of Alclad if I can get it to fit decently.

Thanks for your efforts.  I googled Picket Bros, too.  Nice pipes, and they're all smooth elbows.  I just can't get the elbows as smooth.

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