Fabricating a 2-1 exhaust

[GuzziMoto]

Do a Goggle search for Ducati superbikes, or Honda SP1/SP2. All used 2-1-2 with the most possible success on racetracks.

 

Go for 2-1 if you like the look of it, that's what counts for private road use. In another thread you mentioned that F/I and cylinder selective tuning is not your thing - in this case consider a 2-1-2. Anyway, have fun, such things always are nice projects.

 

Hubert

The main reason to go with a two into one into two is noise. You can run larger, more open, mufflers when you run two of them and still be under the noise/db limit. The power side of it is in the two into one side. The splitting back to two mufflers is more for noise reduction.

I have never seen a real two into one into two system for a Guzzi, but sure you could build one. It will weigh more than a two into one and likely will not make any more power than the two into one system, but it should be quieter.

In the end it depends on what you want. I do not claim to be a pipe builder, nor do I claim to know all there is to know about building exhaust pipes. I have worked with a real pipe builder in the past and he taught me a lot, including changing some of what I thought I knew. Feel free to google exhaust flow theory or whatever, more knowledge is always a good thing. One thing I can tell you is many people told us our two into one exhaust pipe was hurting power on our Ducati race bikes. But none of those guys ever went by us down the straight. Does a two into one pipe work the same on a 90 degree twin as it does on other engine configurations? No. But it do know it can work very well from personal experience along with working with a real pipe builder.

The stock and aftermarket systems I have seen for Guzzi's, and V11s in particular, are two into two with a crossover or X pipe. That results in some of the benefits of a two into one into two system but the main aspect there is, again, noise reduction. In my opinion power gains are mainly in how you merge the two flows together (along with lengths and diameters of the head pipes). Splitting them up later does not really add power unless your muffler flow was not going to be enough with just one muffler, but it can hurt power if you don't do it well.

One last thing, I have yet to see an aftermarket pipe built to the same standards as a custom pipe. I am trying to decide which two into one pipe to buy for my Aprilia RXV race bike I am building, as yet I have not seen one as nice as a custom pipe. I also have a pipe that a guy in Ca. has built for Griso's that is pretty nice, but it is no where near as nice as the custom pipes we have had built for our race bikes. For a street bike you likely do not need something that nice, but I totally understand WANTING something that nice. I want something that nice for my Aprilia AND for my Daytona. We will see which, if either, gets it.

[sp838]

If it's good enough for Dr. John....

 

 

and:

 

a slightly more elegant replica:

 

rear view of the MGS-01:

[docc]

Looks like Dr. John went with the Equal Length Header Theory. And if you're gong to post big, bold rear views of sexy, curvaceous Italians - it could beg the limits of technical discussion.

 

Seriously, I don't understand why the typical Guzzi V-twin 2-crossover-2 doesn't qualify as 2-1-2  ?

[helicopterjim R.I.P.]

Notice that if you go 2 to 1 then you need considerable volume to exit the gases.

 

The MGS-01 comes with a 2 to 1 but Guareschi Moto found that there is a lot more horsepower to be had going 2 to 1 to 2. I can see from the dyno charts that it does suffer at the high rpm's.

[Bjorn]

Love the asymmetrical headers! got lots of pictures of cool guzzi exhaust on my laptop. I thought about it, but considering the time of year and the time that would take ill stick to the original headers. Since you need to do something about the oilcooler location.

 

As far as the 2-1, Im just going to try and see where i end up. Nothing is certain beforehand (sound, performance etc.) I wont cut up any of the original exhaust parts, so can always go back. 

[68C]

You could start off by making a simple jig.

 

Take your old rear crossover section and slide two pieces of pipe into the foward inserts.

Weld those pipes to piece of metal to join the two.

Slide the original crossover off.

 

You now have a jig which gives the position of the original downpipes/headers.

 

You can elaborate on this by welding up an 'H' shaped base and a couple of sturdy uprights, now weld on the jig at the same angle it would be on the bike. Playing around with bits of plywood and other welded up bits should enable you to ensure the new system wont foul the rest of the bike. Decide how it is to be secured/mounted to the bike and add the jig points.

 

You can now go into mass production or rent out the jig.

 

DO NOT WELD ANYTHING WHILE IT IS ATTACHED TO THE BIKE OR YOU WILL NEED A VISIT FROM KIWI-ROY.

[helicopterjim R.I.P.]

Love the asymmetrical headers! 

 

The MGS-01 has asymmetrical headers but the Dr John is equal length.

[GuzziMoto]

 

Love the asymmetrical headers! 

 

The MGS-01 has asymmetrical headers but the Dr John is equal length.

 

I think he was referring to the design, the way they are run, referring to the way they run down one side and not the other. Much like the way a swingarm can be asymetrical. 

[GuzziMoto]

Looks like Dr. John went with the Equal Length Header Theory. And if you're gong to post big, bold rear views of sexy, curvaceous Italians - it could beg the limits of technical discussion.

 

Seriously, I don't understand why the typical Guzzi V-twin 2-crossover-2 doesn't qualify as 2-1-2  ?

A crossover is not a collector. A crossover simply allows for sharing, a collector merges the two (or more) flows together. You could then split the merged flows back apart after the collector, but if you don't have a collector and the flows never actually merge into one then it is not a two into one or two into one into two set up.

X pipes and crossovers are in a different catgory from collectors. Within collectors there are many styles and types. More complex ones that do a better job of merging the flows result in better performance but tend to be more difficult to make and thus more expensive. The ones you see on production OEM and aftermarket systems are generally oriented more towards cheaper to build than working better.

[GuzziMoto]

You could start off by making a simple jig.

 

Take your old rear crossover section and slide two pieces of pipe into the foward inserts.

Weld those pipes to piece of metal to join the two.

Slide the original crossover off.

 

You now have a jig which gives the position of the original downpipes/headers.

 

You can elaborate on this by welding up an 'H' shaped base and a couple of sturdy uprights, now weld on the jig at the same angle it would be on the bike. Playing around with bits of plywood and other welded up bits should enable you to ensure the new system wont foul the rest of the bike. Decide how it is to be secured/mounted to the bike and add the jig points.

 

You can now go into mass production or rent out the jig.

 

DO NOT WELD ANYTHING WHILE IT IS ATTACHED TO THE BIKE OR YOU WILL NEED A VISIT FROM KIWI-ROY.

If you do that make sure you can remove your parts from the jig you welded. I know that seems obvious but I also know that with some pipe layouts you could end up unable to take it back apart. You might run into that with the bottom crossover section if your head pipes turn inward before they connect to the crossover. If so, then you would need to make it partially unbolt.

If you dis-connect the electrics, especially the grounds, you should be able to weld with them in place. But it is obviously safer to remove any valuable electrical parts. In the past we have always had our custom exhaust fabricated directly on the bike. No jig used. But it is a viable way to go if it will work for the section you are building. Being able to remove is key.

[Bjorn]

Yes asymetrical as in the looks

 

I usually try to avoid welding on the bike if i can. If i need to,i always remove the batt. And vital electrical components like the ecu.

 

Nice to see a lot of people involved here thanks for all the tips and tricks so far.

[Bjorn]

Went shopping today for a muffler and some exhaust parts:

 

found a nice second hand laser titanium duo tech muffler. To be mounted on the LH side, with (removable) dB-killer and everything. Right now im trying to find out what angle i want for the muffler. I find the stock cans a bit to low/horizontal. This is how i got it mocked up right now.

 

 

Pictures arent great, but you get the idea

Its going to be tricky to fabricate the collector, because i want to keep the middle stand. 

[68C]

I am interested in your middle stand. Any chance of some photos and dimensions, I tried to make one up without much success. Could not get the geometry right, exactly where in space to have the pivot etc.

[LowRyter]

I'm not sure of the performance differences.  You MIGHT assume that a single exhaust would increase low and mid range at the expense of top end power.  But you know what that say about ASS-uming.  One thing is that a single muffler weighs less than two.  I would guess that on the street that either could be make to work with little difference in performance.  

 

I do remember the Honda RC51 Superbike Twin Cyl 1000 of the early 2000s.  Nicky won the AMA Superbike with one pipe and Colin won the world title with two.  So it appears both can be made to work.

[Bjorn]

I bought a stock collector, but didnt like it. The fitting was crap so i made my own. I calculated the outline of both pipes, making the cut so the 2 smaller pipes merge into the diameter of the larger 1

 

Because the new opening is not completely round, squash the large pipe in the bench to make it oval.

 

 

Weld her up with some backing gas and your done