Time to talk exhaust and it's gonna have to be custom

[bkahler]

There comes a time with every project where if you want to drive it then it's going to need an exhaust system

 

 

Since I have a split exhaust manifold I have to come up with a totally custom system.  First off, I do not want to run a complete dual exhaust system.  I want to run two into one before the muffler with just one tail pipe running out the back.  I realize there are arguments for and against dual exhaust but for me a single muffler and tail pipe is what I'm looking for.  

 

There are several issues that I will have to deal with and the first is pipe diameter.  I have the remains of an original exhaust flange with a short section of pipe still attached to it and it's 2" pipe.  The person that added the 2nd exhaust dump keep the pipe size at 2" but the flange has different bolt centers compared to the original flange.  3-3/8" on the original and 3" on the new flange.  I've been searching for a while and have not been able to locate any new flanges that will work with either of those patterns which means I will likely have to fabricate my own flanges.  

 

Next issue is what size pipe for the down pipes from the flange to where they merge.  I'm not an exhaust expert but I've previously been led to believe that since the original pipe was 2" for 6 cylinders that I should down size the two down pipes to about 1-1/2" each and merge them into a 2" section.  Since the exhaust flanges are 2" that means I would need a reducer section coming off the manifold, i.e. 2" to 1-1/2".  Something like these only with 2 bolt flanges.

 

 

 

Building the exhaust system is something I would like to try and tackle myself, at least until I prove that I can't handle it and then take it to the pros!  I've been looking at tubing rollers and surprisingly this Harbor Freight roller actually has fairly good reviews.  So I'm considering getting one of these and giving it a go.  

 

 

 

Thoughts anyone?

 

 

[47 dodge 1.5 ton]

I’m far from an expert on these motors but, I would advise to think bigger. I would go 2” until the y pipe you want, then 2 1/2” or even 3” to the muffler. Size down after muffler if you want it to be a little quieter.  You spent a lot of money in your dual carb/exhaust and to reap any benefit, let it breath.

 

  Looks like a really nice job on the linkage, heat riser for the dual set up.

[bkahler]

3 minutes ago, 47 dodge 1.5 ton said:

I’m far from an expert on these motors but, I would advise to think bigger. I would go 2” until the y pipe you want, then 2 1/2” or even 3” to the muffler. Size down after muffler if you want it to be a little quieter.  You spent a lot of money in your dual carb/exhaust and to reap any benefit, let it breath.

 

Something I had not considered is whether or not the factory undersized the original exhaust system.  The 454 in my motorhome uses 2-1/2" pipe per side into a two input port muffler then to 3" on the outlet of the muffler.  The header down pipes are around 1-3/4" or so (maybe 2") and then all four combine into a 3-1/2" collector.  So it's pushing 227 ci through 2-1/2" where Dodge was pushing 218 ci through 2".  Your argument definitely has some merit.  

 

For me the only problem with 2-1/2" pipe is the HF tubing roller only handles 2" which means I'd have to find an alternative for bending 2-1/2" pipe. 

 

Yes, I do want a quiet ride.  I like to hear the wind, not the exhaust ?

 

3 minutes ago, 47 dodge 1.5 ton said:

  Looks like a really nice job on the linkage, heat riser for the dual set up.

 

Thanks!  

[Dave72dt]

I don't know if you'll get the bends sharp enough with a tube roller especially if you have to reverse the curve to snake around something .  I'd suggest purchasing some prebent 45's and 90's, some straight tube and cut and weld together as needed to form your system.   I know Walker has prebent sections as well as Y tubes and if not, the performance catalogs do.  A pair of 2" downpipes disappearing under the cab into the Ypipe  would look cool, 1 3/4 is probably big enough.   2 1/4 or 2 1/2 into the muffler is plenty, 2 if you use the 1 3/4.  I'd only step the output size up one size max from factory.  Too big a system can be as detrimental as too restrictive.   JMO, it's how I would build it if it were mine.

[bkahler]

On 12/30/2021 at 1:04 PM, Dave72dt said:

I don't know if you'll get the bends sharp enough with a tube roller especially if you have to reverse the curve to snake around something .  I'd suggest purchasing some prebent 45's and 90's, some straight tube and cut and weld together as needed to form your system.   I know Walker has prebent sections as well as Y tubes and if not, the performance catalogs do.  A pair of 2" downpipes disappearing under the cab into the Ypipe  would look cool, 1 3/4 is probably big enough.   2 1/4 or 2 1/2 into the muffler is plenty, 2 if you use the 1 3/4.  I'd only step the output size up one size max from factory.  Too big a system can be as detrimental as too restrictive.   JMO, it's how I would build it if it were mine.

 

Dave, thanks for the info on the tubing rollers.  I've never used one and hadn't looked at the specs to see what they were capable of.  

 

Your comment got me to thinking about where to get appropriate pre bent parts and that led me to check out DCM Classic's and they listed the down pipe as a separate item.  So I called and talked to Steve about what my situation is and what I'm trying to do.  Between the two of us we worked out a potential solution to the first part of the equation which is getting two pipes from the manifold(s) to under the cab.  Tonight I need to take some measurements and tomorrow I'll call him with the info.  What it looks like I will be doing is buying one original down tube assembly and then buying a second one where the flange is not actually welded to the pipe.  

 

This would allow me to swivel the front pipe to an orientation that will allow me to bring the two pipes together after they pass under the firewall.  The point where the front down pipe connects to the manifold it's a little higher than the rear so I need to find what that difference in elevation is and also I need to measure how much longer the down pipe needs to be in overall length since it is farther forward than the rear down pipe.

 

So hopefully sometime tomorrow I'll know about how much the two pipes will cost and get an order placed.

 

Oh yeah, currently planning on 2" down pipes as that's what he has to offer and it just simplifies things for me.  What sizes for the downstream pipes I'll worry about later.

 

Stay tuned....

Edited February 10, 2022 by bkahler

[Dave72dt]

Take a look at the Y pipes since that will have a direct impact on the second down pipe length and final placement.

[bkahler]

1 hour ago, Dave72dt said:

Take a look at the Y pipes since that will have a direct impact on the second down pipe length and final placement.

 

This is one Y Pipe I'm considering.  Two 2" inlets and one 2-1/2" outlet.  The way the front manifold dumps both pipes should be able to run side by side under the firewall.  

 

I also noticed DCM Classis's has a complete exhaust system so I plan on talking to Steve about possibly building a hybrid kit.  Shipping isn't going to be cheap so buying everything at once should at least save a little in shipping costs.   I measured the height difference and it's 1-1/4" with the front needing to be 1-1/4" longer on the down section.  It's also 9" farther forward than the rear dump so the overall length will need to be 9" longer.  

 

I'll know more sometime tomorrow morning

 

[Dave72dt]

Or the rear pipe could be 9" shorter, depending on where it ends.  Common ID_OD adapter fitting would give you that 1 1/4 on the other end if needed or part of the 9" salvaged from the rear pipe cut.

[bkahler]

On 12/30/2021 at 6:17 PM, Dave72dt said:

Or the rear pipe could be 9" shorter, depending on where it ends.  Common ID_OD adapter fitting would give you that 1 1/4 on the other end if needed or part of the 9" salvaged from the rear pipe cut.

 

That's kinda what I'm hoping.  it would be really nice if this could turn into a semi-bolt in setup.  Yes, I will have to weld where the front down pipe leaves the flange and I think I will have him leave the rear flange to pipe connection loose as well so I can just move things around to where they line p with each other and then do tack welds before removing for complete welding.

 

I'd really like to have the exhaust in place before starting the engine but we'll see how things go.

Edited January 10, 2022 by bkahler

[BobDeSoto]

Are you aware of a pneumatic tool that can expand exhaust pipe?

It fits in your air gun, spins, then expands and stretches the pipe enough to get the stubborn ones together.

Still needs to be clamped when you do get it together.

[JBNeal]

When I got the '48 and '49 running, I rigged up a downpipe from the manifold and drove the trucks into town to the local muffler guy...who was strategically located within spittin' distance of the best chicken fried steak place in the area   I talked to him beforehand to tell him what I wanted, he gave me some suggestions and pricing on pipe and mufflers, squared everything away a few days ahead of time, then rolled into town wearing earplugs, let him do his magic while I chowed down for a bit, then headed back home with a nice sophisticated ride.  After nearly 20 yrs, there's just a few rust spots on the muffler and downpipe.  I had the remnants of the original tailpipe, which went up and over the rear axle and had a slight angled bend at the exhaust, something I knew I could not do, but the muffler man's machine knocked that out in two shakes of a pig's tail.

[Tooljunkie]

Muffler shops can usually handle just about anything. Failing that, i did the right thing and ordered a 2-1/4” exhaust kit from amazon. Built my dual exhaust with ease. Be aware, you can buy dual inlet,single outlet mufflers. 

[bkahler]

19 hours ago, BobDeSoto said:

Are you aware of a pneumatic tool that can expand exhaust pipe?

It fits in your air gun, spins, then expands and stretches the pipe enough to get the stubborn ones together.

Still needs to be clamped when you do get it together.

 

Yes, I have several different sizes.

[bkahler]

19 hours ago, JBNeal said:

When I got the '48 and '49 running, I rigged up a downpipe from the manifold and drove the trucks into town to the local muffler guy...who was strategically located within spittin' distance of the best chicken fried steak place in the area   I talked to him beforehand to tell him what I wanted, he gave me some suggestions and pricing on pipe and mufflers, squared everything away a few days ahead of time, then rolled into town wearing earplugs, let him do his magic while I chowed down for a bit, then headed back home with a nice sophisticated ride.  After nearly 20 yrs, there's just a few rust spots on the muffler and downpipe.  I had the remnants of the original tailpipe, which went up and over the rear axle and had a slight angled bend at the exhaust, something I knew I could not do, but the muffler man's machine knocked that out in two shakes of a pig's tail.

 

Brian, I've thought about doing that but the few places that are reasonably close I wouldn't trust working on a go-kart let alone my truck.  What's made things even worse is all of the shops are literally swamped and you have to take your vehicle in for them to evaluate, they give you an estimate as to how much and then give you a date when you can bring it back to get the work done.  This is mostly due to them not being able to hire good help and get them to stay.  Sound familiar?

 

The more I look at the two exhaust manifold dumps and talk to Steve at DCM I'm pretty sure buying the kit that he sells with an extra custom sized down pipe will just about do the job.  Only thing that should be needed is a Y pipe and some welding on my part.  I'm waiting on a call back from Steve on a few other details, but that probably won't happen until Tuesday.  

 

[bkahler]

On 12/30/2021 at 9:58 PM, Tooljunkie said:

Muffler shops can usually handle just about anything. Failing that, i did the right thing and ordered a 2-1/4” exhaust kit from amazon. Built my dual exhaust with ease. Be aware, you can buy dual inlet,single outlet mufflers. 

 

Yep, dual inlet single outlet is one of the things I'm talking to Steve about.  It might simplify things but until I have the details it's all a guessing game.

 

Thanks!

Edited January 4, 2022 by bkahler

[47 dodge 1.5 ton]

So as my situation was a little different from you, I went another route. 1st— I bought a 90, and some 45’s and tried to make my own. I was not happy with the outcome. Napa took everything back except of course the 2 1/4” pipe I cut for my fabrication. I did only buy enough for (1) dump though. 2nd—- I bought flexible pipe and just put glass packs on. I wasted about 75$ but can drive to a custom shop when I have time and get a quality job that does not look like something a high school kid put together. 
This would allow you to hear you motor very well while tuning as it is obnoxious under a load. Also allowed me to make changes, example— I had too much heat at the battery box for my liking. My duals are much more simple than yours but still wanted a close fit for steering rod clearance.

 Just a thought that I wanted to pass on.

Edited January 3, 2022 by 47 dodge 1.5 ton

[47 dodge 1.5 ton]

Although I most likely will change this look at final fit, it sure gets a lot of attention.

Edited December 31, 2021 by 47 dodge 1.5 ton

[Tooljunkie]

It was a challenge figuring out where to run exhaust. Lots of work to get duals out the back like i wanted, and wanted it easy to remove. Side shot shows muffler and outlet under running board

[49D-24BusCpe]

Gentlemen,

 

    Here's my approach with a 25" 274 cu. in. engine in a D-24 passenger car. We fabricated a 6-3-2-1 system using Langdon "Spitfire" cast exhaust headers. The manifold  outlets are 2 1/4" and they merge into a 2 1/2" pipe that feeds into a (2 1/2" inlet, 2 1/2" outlet) performance muffler, and then to a 2 1/2" tailpipe to the back of the car.

 

    Perhaps you could look at a similar approach?

 

Walt

 

 

 

[lostviking]

I'd run 2 inch pipe, one on top of the other following the stock route. After the cab, is where I would mount the 2 into 1 muffler. Then I'd continue out using the stock route and 2-1/2 inch tubing. The motor isn't huge, and it doesn't rev high. That is more than enough to give it a lot of breathing.

 

To each their own, but that is how I plan to do my 230 after I rebuild it. It will use the dual carb intake I have, Red's 3 into 1 headers, an Edgy head...but one of the new designs that the Montana Mopar boy's are working on, one of their cams also. If I'm rolling in money, which isn't likely but heck...I can dream a bit, I'll use a set of those CP forged pistons and H-beam rods. They are expensive, but with the oiling done right and the crank prep'd I will be able to rev quite a bit over stock.

 

Or maybe, just the first part of all that, and no piston/rods. It will still be a very nice motor and sound great. 

[JBNeal]

On 12/31/2021 at 3:22 PM, bkahler said:

Brian, I've thought about doing that but the few places that are reasonably close I wouldn't trust working on a go-kart let alone my truck.  What's made things even worse is all of the shops are literally swamped and you have to take your vehicle in for them to evaluate, they give you an estimate as to how much and then give you a date when you can bring it back to get the work done.  This is mostly due to them not being able to hire good help and get them to stay.  Sound familiar? ...

aw geez I reckon I'm kinda spoiled then as the custom exhaust shops around here have some nice quality products and craftsmanship to choose from...none of those "we can make it fit" einsteins in these local shops  

 

 

 

[bkahler]

20 hours ago, JBNeal said:

aw geez I reckon I'm kinda spoiled then as the custom exhaust shops around here have some nice quality products and craftsmanship to choose from...none of those "we can make it fit" einsteins in these local shops  

 

 

 

 

Hmm, I've worked with guys like that before ?

 

There is one place that I would consider going to here locally but they are so back logged it's not worth the effort and I've noticed the last couple of times I had them work on my vehicles the work was rather sloppy with no attention to detail.  I'm going to be generous and pass that off as they are just to busy to worry about the small stuff....

 

Based on the location of the two manifold dumps the front dump is about 3" closer to the frame rails than the rear dump.  That means the front pipe can run to the rear beside the rear pipe with about a 1" gap between them. 

 

 

 

I found a Y pipe that that has 2" inlets with a 2-1/2" outlet.  The inlet pipes are on about 3" centers which means there is about 1" between the two pipes.  In theory that should match up with my two pipes fairly well.  I'm still waiting on a call back from Steve at which time I'll see if he can provide the rest of the piping in 2-1/2" size instead of the standard 2".

 

More to come....

[52b3b Joe]

I'm a little late to your post, but I've built two complete systems now for these flatheads. I called every exhaust shop worth calling in my area, and I wasn't going to spend the money they wanted for a new exhaust and the "kits" available were just as much. Both cars were unmodified single manifolds, but that doesn't make much difference. I bought an assortment of 2" aluminized mandrel bends and pieced mine together using 2" aluminized pipe from front to rear. On your truck, I'd personally run 2" down pipes to the muffler and a 2.25" tailpipe. I think a 2" tailpipe would honestly be big enough. I think most of your performance gain is coming from efficiently removing the gasses out of the engine with the split manifold. In my opinion, a 2 in 1 out muffler would be best and I would clamp the muffler connections. That y pipe looks like it might be a challenge to weld, but I've never done one to know for sure. I had a lot of fun making these systems, but it's not a 100% clean look unless you were to grind all the welds smooth (which I didn't do). I also wouldn't have attempted it without a lift. I mocked everything up on the car and pulled it off to finish welding. The tail pipe came out nearly identical to the original exhaust for the car, so I must have done something right lol. The original tailpipe actually had the mopar part number stamped in it still, but I didn't like the small 1.5" exhaust size. I think each system costs about $150 and about 5-6 hours of time. This is just my opinion and thought I'd share my experience with doing an exhaust on one of these. Maybe it'll help some, but maybe not. 

[nkeiser]

I have Fenton style headers from Langdon. When my uncle had this in the late 80's, he added the stacks. When redoing it, I had to keep them. I kept the pipes separate but added an H pipe. I have an 18" Cherry Bomb on each pipe. I used 2" aluminized tubing and bought some premade mandrel bends to splice in where needed.

[bkahler]

11 hours ago, nkeiser said:

I have Fenton style headers from Langdon. When my uncle had this in the late 80's, he added the stacks. When redoing it, I had to keep them. I kept the pipes separate but added an H pipe. I have an 18" Cherry Bomb on each pipe. I used 2" aluminized tubing and bought some premade mandrel bends to splice in where needed.

 

I'd like to hear an audio of how that exhaust sounds!  Why don't you record a short video of the engine running and put it on YouTube?