Some exhaust questions(stock parts)

[snrusnak]

I'm looking to modify my exhaust soon and had a few questions:

Are the 9 and 12 mufflers the same in terms of pipe diameter? (I know the 12's have the valve).

Are the 9 and 12 headers the same size in terms of the pipes off the cylinder heads, and also where they merge at the muffler?

Does anyone know the size of the pipe inside the muffler of a 9(and 12 if it's the same...)?

Thanks.

 

[wolfo68]

9 headers are smaller, but where it meets the head they should be the same.
The 9 and 12 headers can be swapped between bikes. the 9 and 12 mufflers are also swappable.
The mufflers should be the same aside from the exhaust valve.
The outlet should be a 2" on both headers.

If I'm wrong someone please correct me, this is just information I've gathered from browsing.

 

[snrusnak]

Thanks for the response.

I wondering if there's any benefit to "upgrading" to a 12 header. I plan on a bored TB and intake/exhaust and probably dyno tune. I don't want to do any internal mods, at least not anytime soon. Just wondering which header would be best for my application.

That brings up another question. Do the 9 and 12 have different TB's?

As far as the muffler, do you know the size of the pipe in the muffler? I need to order some pieces so I can modify mine, but need to know the size of the internal pipe.

 

[wolfo68]

the 9 tb is smaller, and yes upgrading to the 12 header or 12 tb or both will give you gains. talk to xtremelow about the internals, I know he's been in there before.

I know xopti (michael cobb) has a dyno of his 9 with a 12 tb, and I believe he put 12 headers on it.

There's also a custom header overseas which gives better gains than both. I can't think if it right now, but I'll find the link for you.

edit: Trojan Horse 45mm equal length headers

 

[snrusnak]

Thanks for the info. Seems kind of dumb to make smaller headers and TB for the 9 if it would make less power. Why wouldn't they save money(by only designing and making one size parts) for both engines if they performed better anyway?

Maybe I'll skip boring my TB and just buy a used 12 TB. And thanks for the link to the trojan header, but I am on a budget so think I may just look into a used 12 header.

 

[wolfo68]

I'm not really sure why they did it, but it may have something to do with emissions.

 

[snrusnak]

Bump....

xtremelow?
xopti?

You guys know the size of the pipe in the muffler?

 

[snrusnak]

Well I just had some common sense hit me and went and measured the outlet/tip of the exhaust pipe. It's 2" (makes sense if that's what the merge pipe is).

 

[toddnet33]

If you change your pipe you will reduce your horsepower unless you change your map, be prepared to do battle with your ECM. I have been trying without success to change my map with ECMSPY, I can not find an exact map for my exhaust and another problem is finding a shop that will dyno tune the bike, no body will touch it.
I'm getting frustrated, I love my XB12R but I'm tired of the hassle, I'm thinking about going back to a Japanese bike, maybe someone will intervene and help me before I do something rash!

 

[snrusnak]

I'm very familiar with exhaust sizing. Probably the biggest myth on the forums is that you need some back pressure for low end torque. This is not correct. Less back pressure is always beneficial to power potential. The thing most people overlook is exhaust gas velocity(pipe size). I won't lose any power with what I'm going to do. It should be about as good as possible, actually. I see a few issues with some of the aftermarket options(even the buell race muffler). They leave some power on the table.

I will be doing a dyno tune once I get the exhaust and intake done (including headers and TB).

 

[CrazyTexan]

^^^You have an XB12 and changed your exhaust pipes???? What did you change them to thats killing your power?

 

[toddnet33]

I have a spec ops pipe as seen here:
http://www.specialops-online.com/4436.html

The pipe was on the bike when I got it, along with a K&N
air filter, I did the breather mod and air box mod.

However I did find out today that Atlanta Harley Davidson does dyno tuning on Buell bikes, so I will be spending $360 to tune it for maximum power.

 

[FlaXB9R]

Sean the internal pipes are two different sizes . Can't remember off the top of my head but I measured mine when I gutted it . I did post it for someone so I maybe able to find it or you can try to search through my old post .


@ todd Check out the tuniversity . He's a site sponsor and will teach you to tune yourself . The link is on the right of this page .

 

[snrusnak]

Thanks man, do you know which pipes were different sizes or where it changed? There's basically 3 parallel pipes, right?

 

[FlaXB9R]

snrusnak here you go You owe me[cool]

 

[snrusnak]

Thanks pri....I mean buddy!

So the left pipe in your picture is the oil cooler side, and the right pipe in your picture is the belt side? And the center pipe that was already removed is the exit pipe? I measured my stock exit it is 2". Also I think the header to muffler is 2". If this is all correct then that's all I need to know.

 

[snrusnak]

And all the pipe in the muffler is mild steel, correct?

The header is stainless, no?