2nd Gen Non-Engine/Transmission What size square pipe are your stacks on?

[WadePatton]

I've read about 4x4, 6x6, and 2x6. I'm leaning toward 6x6--for 5" stacks.



Yes, I have problems with the flow offered by 2x6. Maybe 2x10---nah.



Install photos solicited.

 

[Dsul]

I run 6x6, 3/16" thick.

 

[JJW_ND]

4x6 here

I modeled mine after Rob Thomas's design. I would stay with either the 4x6 or 6x6. The 4"x6"x60"x3/16" is a heft chuck of metal.



The other positive advice I can add is running inner 4" pipes with the outer 5" stacks just for looks. You loose all the soot issues and problems with water that gets in the pipes. I have went through several car washes with not any black soot spray issues) You also loose allot of noise. Im sure duel 4" flow enough for lots of power. To make the bends less restrictive, you could weld 4" (or 5") elbows into the 4x6 or 6x6 tubing rather then just cutting out a 4" (or 5") hole and welding the pipe on.



I just welded the 4" inner pipes on and then welded a 5" coupler (coupler had slots on top and bottom) over the 4" inner pipes for the 5" stacks to slip into. We did not weld the slots shut on the 5" coupler when welding it to the 4x6 so any water that gets in the stack (most all runs down the outer 5" stack) will just leak out. No worries with exhaust leakage or soot. I made a few dyno runs and street runs with lots of smoke and the soot marks on the inner pipes only makes it a few inches down. The bottom third of the inner pipe or stacks are clean. In fact, I think a slight vortex/vacumn is created with the exhaust exiting the top that some air is probably sucked int he slot openings at the bottom cooling things off slightly. My inner pipe goes to within a couple inches of the bottom opening on the 5" turnout. I can hold my hand on the all but the top foot of my stacks after running at interstate speeds for hour or more.





This 4x6 or 6x6 gets pretty warm even running empty and down right hot if pulling hard. I found some cheap exhaust wrap at http://store.hamiltonmarine.com/browse.cfm/2,689.html . I wrapped the entire 4x6 piece and both 4" inner pipes on mine with the 4"x100' roll with over half still left.



... . sorry to ramble!



jjw

ND

 

[WadePatton]

NO, please ramble--that's good information.



I'm working on a design in my pointy little head.

I'm thinking about welding tabs onto the box section and using rubber muffler hangers to bolt through. Probably have to make the tabs 3-4 inches long to keep them from getting hot enough to melt the rubber.



Reason--to allow airflow around the box and keep it off the bed--preventing paint rub/cook through and subsequent rust.



Probably also use diamond plate to cover everthing.



Interesting about the 4/5 inch soot/rain thing. I've been planning for a miter cut top with drainage holes--but the square tube sorta messes that up unless I do the liner thing.

Is there any difference in the sound of a box-section setup and pure tubing?



Lot of welding though. I can weld, I just have to borrow equipment. Actually I LIKE to weld--that's the scary part.

 

[Hammer]

Wade. .

If you do a search in the member list here for Oasis-3(aka,Mr. MPH or Stackmiester) you will see a link to his homepage. If you follow it he has the complete parts list for his set in the pictures area along with shots of his set all done. His is one of the cleanest applications for stacks I have seen. M-D member llawrence had a set for sale,I am not sure if they are gone yet check with him if you like those type. Larry is going back to a custom built 5 in duals set underneath the bed now. I'll attach a pic below for you. I am not a fan of the square tube base stacks myself. Although they may be able to limit water/soot problems exhaust flow will be hampered by the square tubing. Hope this helps... ... Andy

 

[WadePatton]

Does the offset there cause any difference from a center-fed setup?

 

[Got Smoke?]

Originally posted by WadePatton

Does the offset there cause any difference from a center-fed setup?

Nope, mine have always been similar to that setup Wade. Both set's.

 

[CRSmith]

The area of a 5" pipe is 19. 6 square inches.

4x6 = 20. 4 sq in

6x6 = 31. 6 sq in



Even though square doesn't flow as effectively as round, you'd probably still be alright with 4x6. Plus, you'd have two of em.

 

[ISBPilot]

4x4 here..............

I have a 4x4 square cross pipe mounted to the bed with 4" to 5" adapters welded to the top of it with 5" turn-out stacks and a 4" elbow welded into the bottom just to the passenger side of the drive shaft. Right stack smokes about a half second before the left, can notice it but can live with it.



Todd

 

[WadePatton]

Thanks for the info. Keep it coming.



Hadn't thought about 4x6. Just out of curiosity, what's the area on 2x6? I spose if that size would make it easy to go over the tank-under the bed.



I'm still thinking 6x6 in the bed. Hidden with tool box and plate---oh, but then I just made an oven didn't I. Or at least a hot toolbox.

 

[jtisdale]

4x4 is quite adequate for most single charger trucks. 4x6 should be more than ample to support most twins. JMO

I went 4x6x1/4 for one reason. You cant run a 5" pipe into a 4x4.

The 1/4" is a little overkill, but its all I could find in the area.

 

[TXDSLSHOP]

4 1/2 square 3/16 wall here.

I used a piece of 4 1/2 tubing I had and welded in 5 inch to 4 inch reducers for the stacks to mount. I welded tabs and bolted it to the bed floor. Sounds great and no change in egt's!#ad