Fabricating a 2-1 exhaust

[Bjorn]

Hi!

 

I've been having this idea to change the exhaust set-up on my bike for a while now. Looking at a lot of pictures to get some ideas, I think i want to build a 2 in 1 exhaust. I have build some exhausts before but these where more ''form over function'' (i guess ). So before i start building and go through the hassle of dialing everything in, I would like to hear some experiences and feedback on the exhaust setting.

 

Dont get me wrong, i really like the looks of the original mufflers. However i do miss some ''sound'' in the low RPMs, and wont miss the weight of the original set-up. So here what i'm aiming for:

 

 

• Increase ride-ability, especially in the low/mid range. Not looking for max HP here!
• Deep exhaust tone, NOT racing loud. I use the bike every day.
• Keep the original headers.
• from the headers, fab a 2 in 1 piece where the original crossover is located (under the gearbox).
• go left or right to a aftermarket muffler.

Here some examples (who doesnt love pictures of pretty guzzis )

nevermind the header set-up on this last bike. (but gorgeous nevertheless)

 

Things I would like some input on:

 

 

• Dont know what the 2 in 1 will do to the exhaust sound/note?
• I know there is a lot of black magic involved with exhaustsystems, gasflow, pipe diameter, length, etc. anyone a idea what the difference is between 2-1-2 vs. 2-1? Again, im looking for a nice sound and good ride-ability.

 

Edit: fixed the layout

[GuzziMoto]

I am a big fan of 2 into 1 systems. We ran them on our Ducati racebikes, and they did well power wise. They sounded like the Devil himself as well. Way better then all the other Ducatis with twin cans. And my Griso has one, seems to work well but I did opt for a right side exit reverse cone system from a guy in Cali. It sounds great as well.

It seems most people with Guzzi's, and Ducatis, prefer the two into two systems. I don't know why.

 

A two into one system has more of a snarl than a two into two system does. A two into two system has a deeper sound with more emphasis on the individual thuds of each cylinder. The two into one system kinda blurs them together. But that is what it does, it applys the energy of one exhaust pulse to help the next one in the other cylinder get out.

 

Technically the stock V11 system is a two into one into two system but the junction between the two pipes is very short and does not do a good job power wise to apply the energy from one pulse over to the other cylinders exhaust. A well designed two into one system will have a larger area under the power curve. A two into two system might make more peak power but likely less power everywhere else.

[Don G]

GPR makes an 2 into 1 system where you use your original head pipes, fairly affordable unless you opt for the carbon fiber muffler.  Don G

 

[Bjorn]

...

A well designed two into one system will have a larger area under the power curve. A two into two system might make more peak power but likely less power everywhere else.

with this, do you mean more grunt from lowdown in the RPM band? Because thats what i use most during my rides.

 

Another benefit of a 2-1 is the fact that i only need one muffler, saving me some money.

 

@Don, I found something on their site. Only one small picture unfortunately 380 B pounds still sounds like a lot of money. I guess I prefer building something myself, hopefully learning something in the process. Thanks for sharing though!

[sp838]

Just buy the GPR, it's cheap, made of stainless steel, looks great, and you'll have it in about ten days:

 

http://www.v11lemans.com/forums/index.php?showtopic=18270&page=3&do=findComment&comment=195561

[GuzziMoto]

 

...

A well designed two into one system will have a larger area under the power curve. A two into two system might make more peak power but likely less power everywhere else.

with this, do you mean more grunt from lowdown in the RPM band? Because thats what i use most during my rides.

 

Another benefit of a 2-1 is the fact that i only need one muffler, saving me some money.

 

@Don, I found something on their site. Only one small picture unfortunately 380 B pounds still sounds like a lot of money. I guess I prefer building something myself, hopefully learning something in the process. Thanks for sharing though!

 

It does not always mean more power down low. It can, but really it is often more about mid-range torque. And a proper designed two into one should make more mid-range torque across a wider rev range than a two into two system.

The best way to think of it in my opinion is less peaky.

 

The GPR system looks nice, and I doubt you will be able to build one for significantly less then that. I have not used one yet, but those that have seem suitably impressed. I would put one on the wife's V11 but she likes her bike the way it is. My Griso has a two into one as mentioned and when I get around to it I want to try that GPR system on my Daytona. I would also prefer to build my own for the Daytona but I know reality is it will take me much longer and cost me more than just buying the GPR system.

[docc]

There is an excellent discussion of exhaust dynamics in Keven Cameron's book, Sportbike Performance Handbook.

 

The idea that exhaust pulses from the "crossover" and then from the canister will affect cylinder filing and, therefor, "flat spots" is heady stuff, but worth considering with any exhaust changes.

 

The placement (length) of the junctions and volume of the silencer(s) will do more to influence performance than whether there are simply one or two canisters.

[Bjorn]

The GPR set-up is the way I want to build it. Im curious about the sound SP838, did you do a sound check?

 

Books/literature are great! Maybe i can find something similar here in Europe. Or somebody has it in a digital form?

[GuzziMoto]

Yea, it is complex and just building a system without understanding all that is a crap shoot. There are so many factors, length of the primary pipes, diameter of the primary pipes, the length and shape of the collector and the following pipe, length and diameter of the muffler. And that is just the basics.

There is power to be made in the exhaust, but also power to be lost.

 

With our Ducati racebikes we worked with a guy named Herb Gebler. He was a dedicated exhaust builder who built all kinds of high performance exhaust pipes for all kinds of race motors. Much of the little I do know about exhaust pipes was either learned from him or proved through working with him. When I first started working with him I thought I knew what I wanted. He showed me that his way (which involved a two into one pipe for our Ducati) was better than my way ( a two into two pipe).

That said, I still would like to build my own pipe, not because I think I can do it better than the pros but because I think it would be fun and cool.

[GuzziMoto]

Oh, and if you, or anyone else wants to try to build your own two into one system you can buy a variety of pre-made collectors from a number of sources.

[Bjorn]

Im aware that power can be gained or lost. And although the GPR system doesnt look bad. I enjoy building stuff myself, and gaining knowledge about it. Im not that old (23) so i dont know shit, but since I started to mess with bikes myself, I did learn a lot of things! From welding to leaning how to machine parts with a lathe or mill. Things I would never have learned by only buying parts (no offense).

 

I made a quick overview of the parts I need and what it will cost:

• 2x 45mm thin walled-tube with a 90dgr bend       (€50)
• 2x +/- 60mm thin walled-tube with a 90dgr bend  (€60)
• a muffler of choise (+/- €180) Here a two i got my eyes on:

1:

2: part reflection part absorption. able to change inserts for my preference (noise level)

 

 

And i want the muffler to be more up high compared to the low mounted originals. I want to start soon, spring has arrived Besides after building i need to get the fuel injection part sorted.

[luhbo]

... but since I started to mess with bikes myself, I did learn a lot of things! From welding to leaning how to machine parts with a lathe or mill. Things I would never have learned by only buying parts ...

 

.... Besides after building i need to get the fuel injection part sorted.

I like your approach. Consider buying a MyEcu for the fueling thing. Not because you really need to make changes because of your new exhaust, just for more points on your 'things still to learn' list. That's real fun.

 

Hubert

[Bjorn]

You mean this stuff  : 

 

 

Its not easy (and not my cup of tea ). I already changed the Fuel map to eliminate the annoying hiccups around 3000 rpm and small throttle openings. Id rather be building a exhaust than fiddeling with FI

[luhbo]

No, this is not what I mean. MyEcu is this:

 

 

or this:

 

->

 

and much more in this direction.

 

Hubert

[Bjorn]

Looks fancy! A/F logger?

 

Called a tuner today who knows something about Guzzi's. I asked him some questions about my new exhaust set-up. Things I should pay attention to. This is a summary:

 

(maybe a open door for some)

 

• Make sure the pipe diameter after the collector is large enough.
• Choose a muffler with a large pipe diameter (65 to 70mm)
• choose a muffler with a large volume in order to dampen the noise a bit.
• 2-1 is indeed suitable for the mid range.

I i do proceed i want to do it right. No point in building something just to find out on the bench its never going to work. He even suggested just buying other mufflers and get it tuned. But that sounds boring and I would like something ''different''