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X pipe muffler

1K views 10 replies 5 participants last post by  cerial 
#1 ·
Been reading Mike Mavigian "Performance Exhaust Systems" book and have a question about a x pipe design.

I have some 2.5" speedway cast "ram horn" manifolds coming and a few pieces left over from a few exhaust kits to build the below routing to get to the passenger side.

Exhaust from the drivers side will make a 90 off the manifold towards the passenger side, go under the pan, then make another 90 towards the rear. Exhaust off the passenger side will make a 90 towards the rear.

The above can not be changed due to packaging.




Once past the 90 sections I will have around 14" wide, around 8" tall, and around 90" long from the back of the motor on the passenger side and have enough room above the axle I do not need a hoop and can have the two pipes a inch apart shoot right out the rear.


What I am thinking is making the below "muffler". Basically cutting the shape(4 together) on a table then welding the top and bottom sections together being 2.6" tall before merging 2 1/2 pipes at the front and rear of them.

I am thinking of having 8 of these X sections in a row for around a 70" long 6" wide and around 3" tall muffler.

The dotted line(mirrored) is where I am guessing the most sound reflection would be done. The idea of tapering the muffler down from a 2 1/2 to 2 3/4(slowing flow) to 1 3/4(increasing flow) before it enters the 3" section then having it go back into a 1 3/4 section (increasing flow) then to a 2 3/4(slowing flow) then to 2 1/2(increasing flow) is that it should create a pulse to scavenge. All the while 1"(per side of 2 1/2 pipe) is unrestricted and passes completely through.

I am thinking having 8 of them should reduce exhaust noise significantly while providing enough savaging for my mild 350/355 to flow easily into the 7000rpm range.

I am thinking of 1/8 steel for construction which should place the thing between 52 and 56 lbs. Not that bad considering the thing will end up around 70" long.



Here is the rough design;



I am thinking it will flow like this(super rough) blue being nonrestrictive, green being less restrictive, pink being restrictive and black being scavenging areas.




I would Like some feedback. On if this thing is going to be restrictive as heck. If it is going to drone or vibrate terribly. Or any helpful information you can give to improve upon it .
 
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#2 · (Edited)
Are those 4 different chambers on each side?? Your 2 90 degree bends will be very restrictive before it even reaches your project and not only is it heavy its coplicated and hard to understand! But in trying to figure it out and sorting out the flow from slow to fast and then slow again its scavenging ability would be non existent the exhaust pulses you are creating would fight each other in my opinnion ! I do not understand what you are trying to do deaden noise or create power or both ! Please explain your end result that you expect??

interesting :mwink:

Jester
 
#3 ·
If by chance your project is that your looking to sell this product with a patent do not post it on here or anywhere else !!! In the past (Yrs ago till even today) racers and hot rodders have come up with speed tricks and fabrications that proved themselves in application at the tracks or on the street only to see them copied produced and sold on the market with no credit or monetary return to the inventors !:eek::drunk::pain:

Jester
 
#4 ·
No I am not doing anything new here it is just a chambered design. Take it and build it if you want.

I have a head design(engine)(4 years designing and revising) I plan on building(once I get a mini Lathe) and testing over the next 3 years. That (fully mechanical easily serviceable)head design is something totally new and will require a few patents. It will make you wonder why we settled for mid 20to30% efficiency for the last 40 years.

Back on topic

I can not do anything about the 90 degree bends in the exhaust. It is a packaging thing. Know that the passenger side has a single 90 while the drivers side has 3 90 degree bends. It being 2.5" I should have plenty of cfm going through the 3 90 bends.
Know that the engine is a 350(355) with stock 478 heads(engine has 6k on a rebuild for $200 carb to pan. I can't complain to much). I am not after power as much as ease in working on this thing.

Maybe this will help it explain the muffler better.
Here is the proposed assembly of the combined 8 of the 8" long 6" wide sections taped together to check fulfillment this weekend;



I know it is hard to see. But do you see how the exhaust would flow straight through/around the diamond middle sections?

I am thinking by having it taper down slightly creating a venturi effect increasing flow through the tapered section. Once out of this section the flow enters a larger open section of lower velocity. But because the majority(2") is flowing through this lower velocity section I am thinking that the exhaust will then be drawn through the next venturi only slightly slower then it entered the first section literately pulling the exhaust through the muffler to a point.



Because this is a muffler sound reduction is what I am really after here. If it flows great great. But sound reduction is what is the goal.

Starting at the exhaust facing you in the picture.

Sound generally travels in a straight line. When it hits that first outer angular surface it will be forced into the path of exhaust flow(shown in the first pict by the dotted line). Then there is a slight reduction where it bounces off the center diamond section in the highest velocity point. Then enters a large open section of lower velocity before hitting the next angular outer section before flow is sped up forcing it to hit the next inner angular surface.
All together I have the sound waves hitting 16 outer sections hard and 16 inner sections to a lesser effect.

Flow wise the amount flowing completely through unrestricted amounts to 2" exhaust single exhaust. But that 2" opens up to 5" then back to 2" moving into the next section.
I should be producing around 330 hp and with dual exhaust that should place me in the 2.25 to 2.5" range. Because I want my torque lower and I am more concerned with this being a muffler. I feel that having 2" unrestricted will be more then fine enough.

Hope that explains it a bit better.

Note;
There is no cat in here. Anywhere. Non emissions state.
The thing is chambered. But done in a way that I feel will be considerably less restrictive then ones(most) that slam the exhaust into a flat wall to reduce sound. Or ones(most) that try to "trap/cancel" sound often causing a reduction in flow.


My concern is that the sound waves slamming into that angular section of each area is going to make a vibration or drone. I am thinking that by having enough I should eliminate this drone(and most of the sound) by the time it exits the muffler and goes out under the bumper into open air not being aimed at the ground in any way.






As far as construction goes this is in my head without using any cad software to reduce scrap.

18-2x2.6 (middle inner diamond straight section)=3x32(.25 spacing=3.5x41 total area needed)
32-2x2.6 (middle inner diamond angular sections)=7x32 (7x41 total area needed)
18-4x2.6 (outer straight section) (3x4) (9x36 total area needed)
32-2.5x2.6(Outer angular section) 3x3 12x30 total area needed.

4
7
9
12=33" tall(35 with spacing)

4-9x32 (top and bottom sections=36x32 (.5 spacing)=38x37

35x44 sheet should cover all the uprights and
38x37 sheet should cover the 4 top and bottom sections with a good amount of scrap that can be reduced once this gets into someone hands who has actually used a cnc table/program.



Any obvious issues with this exhaust?
Yes it will be a bit heavy. But not terribly heavy when you consider that it is a majority of the exhaust system.

Drone?
Sound tone?
Are these things going to flow terribly? I admit I could have this totally backwards here flow wise.
 
#5 · (Edited)
No problem you can design to your hearts content :thumbup: I don't use X pipes or recommend them !

But your concept interested me and wondered how much your design would increase HP over a standard X pipe and muffler designed exhaust systems HP claims or would it lose HP, in your opinion ?. 8 X pipes in a row 70 inches long to deaden noise like a normal light muffler would. In the 60s Chevrolet introduced a chambered exhaust the length from the engine to the rear bumper of the car no cat and no muffler no resonators! It was very light, I seem to remember Yrs ago using the formula 1hp loss per every 10lb of weight added .


As for noise and resonance I was not interested ! Ive seen track tests with X pipes installed and with them removed, on some systems they helped HP a little on others they either did nothing or were detrimental and lost HP! I took that to mean that if your exhaust system is lacking in its effectiveness to scavenge they may help, but if you have a well tuned and designed exhaust they don't work well ! But I do admit x pipes do change the exhaust tone and resonance ! I will not comment on your project! I don't feel its my place to give you praise or to offend you but I will be interested in your end result:thumbup:

Good luck with your project :thumbup:

Jester
 
#6 ·
It is a project.

Here is what I am working on;


Shot on my phone horribly

Truck will weigh 4300-4400llbs when it is done. Not building it for horsepower building it to run it hard until parts break, replace parts easily, work on easily, and drive it hundreds of miles without concern.

Ramhorns should arrive here by Thursday. I have custom driveshafts front and rear which will not work with the novak mounts. I need to modify my fire wall a bit more for easier access to the rear bolts and distributor.
I need 2 more inches rearward to avoid buying new custom driveshafts. But I will modify those mounts this weekend which (improving them) required me to pull 8 bolts (6 of them on angles into the block with no play). To a design that will allow me to pull only 2 bolts vertically(and bell bolts) and slide the engine forward unrestricted and will make replacing the clutch/engine a easy while leaving the transmission in place.

Going to be around a month until I see the exhaust being finished. I guess I will just build it throw it on and see what happens.

I am actually limiting my torque by design to around 300ft/lbs. That's what the 4.7 had. The front axle is a hp dana 30 The rear is a 8.25. I have air lockers in both and I do not feel like replacing them.
Using basic mild 350 engines I should be able to achieve those numbers while driving the thing like I tend to drive my custom rides.
 
#7 ·
I hate to be negative but for only 350 hp 300 lbs/ft torque you are far over designing. Frankly it looks like something the English or Germans would do. Lots of parts, very complex, and no gain....probably a good loss.

You already have shot off the left foot with two 90 deg bends on one side before you get to the other side so any tuning effect is long gone. The cast manifolds are nice but anything downstream is just gas flow. All this chambered stuff is going to do is cause a massive fabricating and welding project. You have a lot more energy than I did 50 years ago so I congratulate you on that.

Why not just run 2 1/2" pipes parallel to each other, expand to three inch pipe then to either separate mufflers or a dual in dual out muffler. At this level there are lots of stock mufflers that will quiet it down to a whisper with little loss if any power. Just look at all the factory hotrods. If you want an X pipe, put it in. You will need a very good dyno to note the difference. If you want to build custom mufflers use 1/8" or 3/16" steel material. It will provide mass to dampen the sound.

I hate to be really negative but just say it your opinion vs my opinion. If we were in a beer joint I say lets have another round, throw in some burgers and fries. LOL
 
#8 · (Edited)
Your staring with a mild 350 and rams horns. 2 1/4 tubing with performance mufflers would be enough.

Engine Master just tested X pipe vs H pipe and no cross over exhaust system on a LS engine and the power difference was 2 to 4 HP. The X pipe did have the a more mellow sound.

If your after a mellow tone use a 2 in / 2 out chamber muffler like a flow master just behind the transmission and then add over-the-axle pipes with mufflers of your choice to get the sound you want. This setup blends the pulses and distributes them across both mufflers and allows you to use even the quietest mufflers with very little loss in total flow capacity.

have you read this ?
http://www.superchevy.com/how-to/exhaust/0505phr-exh/
 
#11 ·
Your staring with a mild 350 and rams horns. 2 1/4 tubing with performance mufflers would be enough.

Engine Master just tested X pipe vs H pipe and no cross over exhaust system on a LS engine and the power difference was 2 to 4 HP. The X pipe did have the a more mellow sound.

If your after a mellow tone use a 2 in / 2 out chamber muffler like a flow master just behind the transmission and then add over-the-axle pipes with mufflers of your choice to get the sound you want. This setup blends the pulses and distributes them across both mufflers and allows you to use even the quietest mufflers with very little loss in total flow capacity.

have you read this ?
Auto Exhaust Science
Thanks for the tech.

Generally on my 2wd piles I would do just as you said. Symmetry down both sides of the transmission (sometimes dual free flowing cats with probes in front and behind) then a X or Y muffler above the driveshaft to second muffler(s) by the diff (offset avoiding axle hump) with angles kicking out. It makes for a cheap system that sounds quiet at idle yet does not sound terrible around 6000rpm.
But I have a transfer case I can not get around on this thing, a fuel tank behind that, and the fact that the belly of this thing tends to drag on logs means I cant go symmetrical like with some cars.

I am just going to build it and see kind of deal. If it makes a horrible drone or weird sound then I will look at something different.
One thing I have wanted to do for a while(this will be my 8th complete exhaust) is just have the thing running dual electronic actuated valves off the headers in this case they would be at the bottom of the 90's that dumped directly at the ground or out towards the fender wells and use a rpm activated switch to open them. It is an option that I could add easily to this system later.

I have room to go dual plane in front of the engine(15-18"" of nothing in front of pulleys and am leaving enough room in between accessories) that turns into a 3" then 180's back to run to quiet it down and go out the back. But, for the meager power this thing is making dual plane would just eat up space.
If I get into larger axles like dual 14 bolts front and rear then I can increase the output into the 430hp range with some spray, vortec heads, using cheap to build/replace 1/2gen short blocks.
But that is a slippery slope of upgrading something only to find something else to replace. Been down that path many times and it becomes tiring. For now I will restrain the horsepower and look forward to just driving the thing for a while.


I am really only concerned with the sound it makes at this point.
I have been the guy (more times then I admit) with almost completely open exhaust who fired up his ride( I drive my junk daily) and watched as lights came on quickly stuffing the thing in gear out of respect.
Quiet exhaust is something I have grown to prefer even if it cost horsepower.

Building this thing to build it at this point. I do not consider it a massive or hard project. I should be able to grind down the pieces at proper angles then clamp and tack and final weld as I go before moving around to another section. If I have all the pieces cut to size I feel it is something I could prep in a day and weld the next day at relaxed pace of letting things cool.

Still a month before I begin it mind you lots to do on the truck. If it turns out sounding like a Vespa then I tried and learned.


Thanks for all the help.
 
#9 ·
This man has the time and ability to tinker with what he has laying around I think he knows all the ins and outs of mufflers and their ability to quiet a car!! It doesn't seem like he is asking about increasing HP or Torque? To me it seems like he just wants to do it and see what it does :thumbup: Thats not a problem in my book and I wouldn't try and discourage him:mwink:

If every tinker or strange idea was discouraged we would still be depending on horses!!

Jester
 
#10 · (Edited)
Regarding the drone issue, I removed the large suitcase muffler from my Hemi Challenger, which has a factory X pipe, replacing it with two Dynomax Race Bullets, retained the resonators at the rear and have no drone. I have read reviews from others who did the same but removed the resonators, they had significant drone.

BTW, I also have a couple of 90's I can't work around, it's not a hot rod project, but able to do it myself in my garage, a little elbow grease cleaning, some VHT aluminum paint and it will look OEM.
 

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