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fiercegerbil

2-1 vs 2-2

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fiercegerbil
Exhaust options for the FZ/MT 07 appear to be limited to 2-1 with the exception of IXIL who makes what appears to be a 2-1-2. I haven't really checked on that exhaust so forgive me if I'm wrong.
It's been mentioned -either here or another forum but I believe here- that a 2-2 is the better setup due to the uneven firing order of the 270 crank. I've tried searching the web for more info but haven't really come across anything. I believe options are important to open up and personalize. Is a 2-2 better? If it is, then maybe the 07 community can push the aftermarket for it. I see a lot of v-twins using 2-2 and being 270's act comparable to them it only makes sense to wonder why the aftermarket hasn't put any out for the 07. Not to mention I have found other 270 parallel twins do have 2-2 available. I leave this to the knowledgeable people here. Pros and cons? I know it comes down to the uneven firing order, gas and wave pulses effecting exhaust scavenging and promoting cylinder fill on intake stroke. If gas and wave pulses are off it can actually interfere with efficiency. Does unequal header length combat that on a 2-1?
Sorry for the long post. Understand that I don't want this to turn into another one of "those" exhaust threads. Merely educational here. Thanks guys and gals!
 

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AlbatrossCafe
I'm not too versed on the subject and don't know much here, but @gregjet has been rampant on the forum about this lol.
 
See his post here for relevant details...
 
I also was holding out for a 2 into 2 exhaust that I didn't have to fabricate myself. I might have to give up on that though.
 

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gregjet
Albatrosscafe,
I am modifying my stance a little about 2-2 after getting a post by another member that led me to the new Divergent close to head exhausts that have started appearing. The Arrow APPEARS to be such an example, my Akros are not. Even though the best example I have seen on a motorcycle is on the YZR M-1 MotoGP bikes and are made by Akro.
Still , if you are making a straight pipe exhaust 2-2 is still the go unless you have access to the new maths they are using for the current close reflectors. "longer is better" is not quite right. On the MT, longer than straight underneath is better unless you build with tiny ID pipes ( a bit pointless). The lower the revs for the peak you are after the longer the pipe an the MT is relatively low rev peak.
If you are using the bike on the road, you don't need ultimate power and the pipes the right length and pulse tuning will only work at the peak rpm you design the system for. Any light weight pipes you like the look of will be fine for the vast majority of riding on roads.
Track , however, where you want every tiny extra pony, go for Arrows or 2-2 IMHO. Have a look at Ducati v twins. Same firingpiston offset. All performance have 2-2.
 
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hobbs
That price tag tho...
 
ouch

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gregjet
Nice find Pattonme. I agree, a set for the bigger brother would be exactly what the doctor ordered. Or a set using the new harmonics ( I wish I could find out more about it. Guess it's a upper engineering secret...)
 

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sorkyah
Nice find Pattonme. I agree, a set for the bigger brother would be exactly what the doctor ordered. Or a set using the new harmonics ( I wish I could find out more about it. Guess it's a upper engineering secret...)
I'll see what i can dig up... i know a couple of my instructors used to race back in the 90's
ill see if they know anything, or have any contacts that might.

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AlbatrossCafe
I would prefer for a 2-into-2 to have both pipes on the same side on top of one another, like on the newer Ducati's. It looks more modern to me. Under the seat would be even better, but that is just a pipe dream lol.
 
Something like this but instead of the 4, just have 2 slightly larger pipes in the middle?
 
http://bellissimoto.com/images/0068.jpg

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delbee1
Interesting subject, I was only speaking to a friend about this a couple of weeks ago about 4 cylider bikes. They are 4 - 2 - 1 and dont match up the firing cylinders, maybe just through lack of space at the front but I know from having tuned cars that the best configuration is matching the 2 paired cylinders together....
Heres a couple of links about it, I would think it would still apply to bikes...
https://en.wikipedia.org/wiki/4-2-1_engine_exhaust_systems
http://www.epi-eng.com/piston_engine_technology/exhaust_system_technology.htm
Possibly on the MT 07 the header pipes would be long enough before they meet into 1 that the pulses do not interfere with each other, the headers on my turbo charged car are much shorter than the headers of the bike and that has a 4 - 1 collector

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delbee1
Here is a properly designed twin scroll manifold for my car. The pulses from the cylinders are seperated all the way to the turbo and the turbo its self also has a divide in it.
phone09012014133_zpshswsja0x.jpg

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gregjet
The problem with the MT07 pipes joining is the fact that the crank is "cross-plane" ie at 90degrees. This makes the pulses extremely problematic because of the phase relativity. It is the same problem as a 90deg Vtwin.

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delbee1
The problem with the MT07 pipes joining is the fact that the crank is "cross-plane" ie at 90degrees. This makes the pulses extremely problematic because of the phase relativity. It is the same problem as a 90deg Vtwin.
Would this not be reduced by the length of the headers?
 

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sorkyah
It would ecept the necessary header length would be about where the stock fender is

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delbee1
It would ecept the necessary header length would be about where the stock fender is
How do you know that? 

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sorkyah
Gregjet estimated a minimum of 42"... after a bit of research my calcs are probably a bit off, but i estimate almost 49" before collector if using a non restictive muffler
 
 
That would put the collector at around the rear axle and the muffler around the area of the ugly stock fender

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