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Hi all. I was wondering if anyone has tried this one before... I was looking at how the flow kinda bottlenecked at the junction. I'm thinking that opening up the junction at both sides and welding a diamond plate over it would open up the breathing quite a bit. What do you think ? the image n the left is stock, the one on the right is what I plan to try.
I have another mod I want to try, but it depends a lot on what y'all think about this one first. Let me know your 2 cents please.
 

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We did a ton of those years back. You need to put a diverter back in. Like the original but not so big. If I remember correctly it was 1" or 1 1/4" square stock. Just seemed to free up the exhaust a bit, along with all the other things that were being done. It was all the little things all together that really made these motors come to life
 

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This works well

This is what our local exhaust guy does to Duc crossovers/collectors.

Very easy to do. All you need to do is know how to cut and weld stainless, or find someone who can.
 

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Here's what a real X pipe looks like:

or:


Notice how there isn't any reduction in diameter or other nonsense with these from Burns Stainless. The diameter at the union is actually much larger than the diameter of any one pipe.
 

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Discussion Starter #7
Dirkwright: will opening the middle completely be too much flow then ? with a cutting torch, it'll take just a few minutes to open it up.
 

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Constricted crossover

My understanding is that the constriction, due to the crimped sides, is not a design/performance feature, but a mechanism to help pass noise rules in various countries.

Anecdotal evidence is that dyno charts before and after showed an increase in torque and power. Maybe psychological, but it really felt different to me after it was done. It certainly sounded better thru the DP cans.

Very cheap HP/Nm and/or therapy!
 

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This is what our local exhaust guy does to Duc crossovers/collectors.

Very easy to do. All you need to do is know how to cut and weld stainless, or find someone who can.
ok - I'll play, and maybe it's because I am sober, but I just don't get how a straight tube section will replace a single radius curve?

I can get how a cb (cheap bastid) could plasma out the center stamping and weld back up a cover with piece of 1mm wall square tube, or even with a tube cut to four sections and put back as a convex star in the center as the routing point, but I don't get your pdf at all...

(too many fumes I guess)

also - the factory design is only really restricted by the 90deg bends in the diverters, and I would bet that the factory volumes on those diverters are real close to 50/50 on cylinder balance. Seems if you opened up that diversion any further, you would run into pulse/flow issues.

all that said, I don't know that it would be worth the effort.

just say'in
 

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Discussion Starter #10
I didn't get the .pdf myself. I think my plan is a lot simpler. I'm going to try this mod this weekend and see what I get. I may need to add something in the middle to divert the flow of exhaust to the sides so it does not oppose the flow from the other cylinder.
 

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I will take pics tomorrow when it is light here in Oz.

See text inside the quote. Nobody is saying it has to be done, just that it works and is very cheap to do.

ok - I'll play, and maybe it's because I am sober, but I just don't get how a straight tube section will replace a single radius curve?

You are cutting off the outer semicircular tubes, as shown by the arrows, not the inside.

I can get how a cb (cheap bastid) could plasma out the center stamping and weld back up a cover with piece of 1mm wall square tube, or even with a tube cut to four sections and put back as a convex star in the center as the routing point, but I don't get your pdf at all...

(too many fumes I guess)

The constriction is the dramatic decrease in cross sectional area (CSA) where the tubing in the crossover is crimped. The exhaust will flow in the "straightest" part, so whilst the total CSA may be relatively large, the direction of natural flow is constricted. I know on my bike, when idling, I can feel the gas pumping from one pipe then the other.

also - the factory design is only really restricted by the 90deg bends in the diverters, and I would bet that the factory volumes on those diverters are real close to 50/50 on cylinder balance. Seems if you opened up that diversion any further, you would run into pulse/flow issues.

Someone want to do a dyno before and after?
all that said, I don't know that it would be worth the effort.

just say'in
 

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i don't think it is a good idea.
If you fully open it, the exhaust gases will face off in the open part, making an high pressure zone that will operate against exhaust flow...
Better to do Separated header for each cylinder!
 

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Dirkwright: will opening the middle completely be too much flow then ? with a cutting torch, it'll take just a few minutes to open it up.
I seriously doubt it. The design is flawed anyway. The exhaust headers, which are the parts before this union, are not equal length, which is a serious flaw. The one from the horizontal cylinder is longer than the one from the vertical. This system was designed for convenience and ease of manufacture and not strictly for performance, in my opinion. To do it right, you'd rip out the old one and design a new one with a proper collector and equal length headers.
 

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My understanding is that the constriction, due to the crimped sides, is not a design/performance feature, but a mechanism to help pass noise rules in various countries.

Anecdotal evidence is that dyno charts before and after showed an increase in torque and power. Maybe psychological, but it really felt different to me after it was done. It certainly sounded better thru the DP cans.

Very cheap HP/Nm and/or therapy!
I would not be surprised at all that Ducati did this for noise purposes. Manufacturers have to jump through a lot of hoops to get their product to market.
 

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See text inside the quote. Nobody is saying it has to be done, just that it works and is very cheap to do.
I did read the text. I am not busting on you, and I know I'm not THAT stoopid. lol

maybe you pm me? or just pwn me here...
 
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