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Ds_tiger
| | Posted on Thursday, March 12, 2009 - 12:10 am: | 
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sounds like you have the muffler for you.
quiet, and visually pleasing
come full circle = OEM!
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Rfischer
| | Posted on Thursday, March 12, 2009 - 08:50 am: |
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There is no Akrapovik for the 1125 app. If and when one appears, I will be very surprised if A] it carries EPA/DOT road use certification, or B] if it does, it makes more power than the stock exhaust.
Caveat: It may be possible to build an exhaust that makes 2 or 3 more peak hp, but that is not the measure of performance. Unless all you are aiming for is a Dyno-Queen. The relevant measure of power is the 'area under the curve' which the stock arrangement excels at. Look at the various dyno charts posted here. They say it all.
(Message edited by rfischer on March 12, 2009) |
186bigtwin
| | Posted on Thursday, March 12, 2009 - 09:51 am: |
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Oh, a racing exhaust specialist can easily make something better than the stock system, The manufacturer always has constraints placed upon it by EPA the aftermarket companies can get by with. If you think the stock exhaust is best, you're drinking too much Buell Kool Aid. This motor ain't magic, and neither is it's exhaust system. It's another ricip gas eating DOHC twin, theres a bunch out there now. Count em Buell, Ducati, Aprilia, KTM, H-D, Suzuki, ect......
You want to know how effeient this engine is? Measure it's BMEP. An 1125 that makes 150rwhp @ 10,000rpm has a BMEP of 169.3. That's pretty good but way short of highly developed race engines. For example a Full race XR 750 that only makes 105rwhp @ 9000rpm has a BMEP of 205. A WSB Ducati has a BMEP of 187.14 if they are truely making 190rwhp @ 11,000rpm
Not saying The 1125 isn't a good motor, it is, but it is not near to being fully developed and exhaust will be a part of it's developement. |
Rfischer
| | Posted on Thursday, March 12, 2009 - 12:02 pm: |
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Ahem....what part of "EPA/DOT road-legal" did you miss?
And, Buell themselves have developed a race exhaust for this motor; one that works and, again, I highly doubt anyone will be able to better it in a meaningful way for the motor as presently built. Change the fundamental parameters of the motor and a different exhaust may be required.
All of which is beside the point as I'm pretty sure Buell has no interest in trying to get into a HP pissing match with Ducati, or anyone else. It would make no commercial sense. Really, it doesn't for Ducati either; without the deep pockets of the Hedge fund that now owns them [which includes the Ontario Teachers Pension Fund Bazillion$$] Ducati would be bankrupt - for the 2nd or 3rd time. |
186bigtwin
| | Posted on Thursday, March 12, 2009 - 12:25 pm: |
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Yeah, I heard that, but what I'm getting at is the best racing parts very seldom come from the factory, HRC exempted....... |
Blazin_buell
| | Posted on Thursday, March 12, 2009 - 12:51 pm: |
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Nice pull Steve, my 137hp at AF1 may not seem so far fetched for some now.
Micah would tell me with the under exhaust, power is limited because of tube length. That's why I'm very interested in the reverso idea ,that way you can get more length and still keep it under the bike. |
Rfischer
| | Posted on Thursday, March 12, 2009 - 12:52 pm: |
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I'm sure Yamaha, Suzuki, Kawasaki, Aprilia, Triumph, would all be very surprised to learn that.
Directly, or indirectly, "all the best racing parts" do indeed come from the OEM's. The aftermarket is there primarily to feed the privateers, tho' many factory race parts, Buell included, can be purchased by weekend warriors if their budgets can stand it. |
Hellgate
| | Posted on Thursday, March 12, 2009 - 05:06 pm: |
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Akrapovics are on a large number of Moto GP bikes, also the street systems I've had from them are TUV approved, typically a higher standard than DOT. Several manufactures have the Akra in their catalog as a performance option. So to say that OEMs develop the BEST parts is not true, in some case they may be the best, but not in all cases.
I will now shut up and go away... |
186bigtwin
| | Posted on Thursday, March 12, 2009 - 05:21 pm: |
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You ever walked around a pit? Yamaha WSB use Akarapovic and Ducati uses Termignoni. |
Clarkjw
| | Posted on Thursday, March 12, 2009 - 05:45 pm: |
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LOL @ Buell being the best exhaust engineers. They had NEVER EVEN HEARD OF A SPARK MAP until 2008. |
186bigtwin
| | Posted on Thursday, March 12, 2009 - 06:07 pm: |
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Might call this overkill but here's little more: Suzuki WSB using Arrow, Aprilia's new RSV 4 WSB using Akarapovic......... |
Blake
| | Posted on Sunday, March 15, 2009 - 04:27 pm: |
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All you experts declaring that equal length header pipes are optimum. Care to explain why?
This ought to be good. Do ya figure that crank stagger/timing might be part of the equation?
Stupid Ducati and Buell employing unequal length header pipes. |
Id073897
| | Posted on Sunday, March 15, 2009 - 04:46 pm: |
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Stupid Ducati and Buell employing unequal length header pipes.
and stupid Akrapovic/KTM also ...
http://moto-ktm-accessoires.kuttler.fr/uploads/big /1052.jpg |
Diablo1
| | Posted on Sunday, March 15, 2009 - 05:49 pm: |
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All you experts declaring that equal length header pipes are optimum. Care to explain why?
This ought to be good. Do ya figure that crank stagger/timing might be part of the equation?
Yes.
No.
That was easy. The reason equal length is best is because you want both cylinders to have optimum filling and equal power pulses for most power and to avoid vibration. The correct length primary pipe for the forward cylinder is the same as for the rear cylinder. Why use two different lengths? Packaging only.} |
Ds_tiger
| | Posted on Sunday, March 15, 2009 - 07:51 pm: |
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Blake-
Clearly you are not "in the know" as well as having failed internet science 101.
Thank you- please drive through... |
Socoken
| | Posted on Sunday, March 15, 2009 - 09:43 pm: |
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I was thinking about what Blake wrote on my beautiful ride this afternoon. It might makes sense. The benefit to having a two into one, or two into one into two system is to allow the low pressure behind a power pulse to draw out the second power pulse more efficiently. If the crank timing was such that the first and second pulses were timed in a way that would allow the first pulse a longer or shorter distance to the collector in order to having more influence in creating a draw effect on the second pulse, it might make more sense to have unequal lengths.
I dont know, it made sense to me on my scenic ride along the bluffs above the frozen and beautiful mighty mississippi. I could be way off. |
Ds_tiger
| | Posted on Sunday, March 15, 2009 - 10:26 pm: |
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Socoken-
You are also way off base and have failed internet logic 101
seek your fortunes elsewhere, sir
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186bigtwin
| | Posted on Sunday, March 15, 2009 - 11:03 pm: |
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Some body will come up with an optimum pipe and it will probably have equal length headers, that will stop the argument, it won't be Buell though. Stop drinking the Kool-Aid. Look at all other Twin racing developement. What up???? |
Oddball
| | Posted on Monday, March 16, 2009 - 12:39 am: |
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Looks a little uneven to me. O2's are at different positions too. This is a plot by the illuminati to confuse the hell outta people. lol Oops, make that Free Masons. The History Channel loves to demonize them.
Had to replace bad link of stock rc8 exhaust, Here's two uneven aftermarket for the rc8.
(Message edited by oddball on March 16, 2009) |
Socoken
| | Posted on Monday, March 16, 2009 - 12:50 am: |
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The only real way to lay this to rest is to make identical systems with one having equal lengths, and the other retaining stock dimensions. If there is a difference, I cant imagine its much, let alone the weakest link in the power making department.
Kool aid is a delicious beverage on a hot day that mixes well with vodka. It is also a much overused cliche. |
Oddball
| | Posted on Monday, March 16, 2009 - 01:01 am: |
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It's a cool drink in that dry Jonestown heat. |
Blake
| | Posted on Monday, March 16, 2009 - 08:02 am: |
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DS,
I'm low on the totem of internet science for sure.
Ted (Diablo1),
"That was easy. "
Posting inaccurate information on the internet is quite easy. Ignoring the effect on one cylinder of the exhaust pulses from another is not so easy, but you've managed to do so. Congratulations.  |
Anonymous
| | Posted on Monday, March 16, 2009 - 08:17 am: |
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Buell pipes, including the race pipe, are designed with the aid of very expensive, very sophisticated computer engine modeling software, which has been correlated back to the actual engine with cylilnder pressure per degree of crank revolution, pressure pulse and power measurements. Guess what? The software predicts you can make extremely good equal OR unequal length pipes. If you do either right, you can make similar power, though in some cases you can get a little more bandwidth with the unequal version. There is one important measurement you have to hold constant, but it's not that both headers have equal length. |
Diablo1
| | Posted on Monday, March 16, 2009 - 06:39 pm: |
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Posting inaccurate information on the internet is quite easy. Ignoring the effect on one cylinder of the exhaust pulses from another is not so easy, but you've managed to do so. Congratulations
There's a good reason to ignore the effect of one cylinder on the other. With a 72 degree V-twin that fires on alternate revolutions of the crank, the exhaust valves of the forward cylinder are closed when the negative exhaust pulse created by the rear cylinder returns down the front pipe. Tuned exhausts are just that....tuned for the sonic pressure waves to return just before the exhaust valve closes to help evacuate the cylinder. The important parameters are rpm range for peak cylinder filling, speed of sound (as a function of exhaust gas temperature and pressure), exhaust cam duration and valve overlap. With those parameters specified, you can easily calculate primary pipe length. Any exhaust pulse that is "in time" for the rear cylinder will be "out of time" for the front cylinder, and vice versa. If the exhaust valve of a cylinder is closed when the exhaust pulse returns up the pipe, no magic can occur that allows that cylinder to "know" or "sense" what the other cylinder is doing. Pulse tuning intake and exhaust is not a new subject. Chrysler published papers on the subject in the 1950s or early 1960s}. I don't think their data went bad with age. |
Bob_thompson
| | Posted on Monday, March 16, 2009 - 07:00 pm: |
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What Anonymous & Diablo1 has stated. Period. +1 and what I tried to say in my post of 3/11 without much success and what I learned in the 70"s from a Weber carb tuning guide. You know the ones they ran on Italian exotics at the time. Thanks much guys for those eloquent and knowledgeable statements. I hope this ends this rather interesting thread and ends some arguments pro or con. Just ride and do not look at your head pipes. Bob |
Blake
| | Posted on Tuesday, March 17, 2009 - 08:40 am: |
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Bob,
From what I just read, Diablo1 is disagreeing with Anony.
One claims that "The correct length primary pipe for the forward cylinder is the same as for the rear cylinder. Why use two different lengths? Packaging only."
While I'm sure that "packaging" is indeed a valid concern, the above claim is inaccurate.
Anony educates us, stating that "...you can make extremely good equal OR unequal length pipes. If you do either right, you can make similar power, though in some cases you can get a little more bandwidth with the unequal version. There is one important measurement you have to hold constant, but it's not that both headers have equal length."
I recall Ducati describing their unequal length exhaust header runs and noting that one run utilized a larger diameter as well.
Diablo1,
"There's a good reason to ignore the effect of one cylinder on the other. With a 72 degree V-twin that fires on alternate revolutions of the crank, the exhaust valves of the forward cylinder are closed when the negative exhaust pulse created by the rear cylinder returns down the front pipe."
If you are talking about a straight pipe and maximum peak HP, you have valid point. But there is a lot more to combined header exhaust tract design than maximum peak HP and the parameters you describe. The goal of a broad powerband and using conjoined header pipes change everything.
Considering just the initial impingement of a negative pressure pulse from an opposing cylinder grossly oversimplifies the issue. Hint: The reflected negative pressure wave from the rear cylinder does not disappear/die upon encountering closed exhaust valves at the front cylinder; it is reflected back down the pipe analogously to how waves in water or sound waves in air are similarly reflected.
Of course whether or not any negative pressure pulse arrives while the exhaust valve is open, and most specifically during the intake & exhaust overlap event depends upon the engine speed as well as exhaust tract geometry.
Overly simplistic exhaust tract tuning as you describe produces a peaky powerband. Not what most folks are after. I guarantee that Buell didn't produce the flattest torque curve ever seen on a production motorcycle by tuning the exhaust tract based solely on the limited limited parameters you describe. |
Badlionsfan
| | Posted on Tuesday, March 17, 2009 - 08:49 am: |
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You people have completely lost this dumb truck driver.
One question tho for those that feel they're being cheated out of a few hp, or are willing to spend hundreds or more dollars for a few hp--
Are you really getting everything out of your bike the way it is now? Are you out riding the capabilities of your 1125r???
Didn't think so. You wanna go faster? Turn off the computer, and go take a track school. Once you get to the point that there is no way that your motorcycle can go any faster weather you or Casey Stoner are riding it, then arguing about header length, dyno numbers and blah blah blah blah that has beaten like a dead horse all frickin winter.
Rant off. Sorry, but it's been building up inside me for a while. I do feel much better now tho. |
Hitman44139
| | Posted on Tuesday, March 17, 2009 - 09:35 am: |
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One question tho for those that feel they're being cheated out of a few hp, or are willing to spend hundreds or more dollars for a few hp--
Are you really getting everything out of your bike the way it is now? Are you out riding the capabilities of your 1125r???
Didn't think so. You wanna go faster? Turn off the computer, and go take a track school. Once you get to the point that there is no way that your motorcycle can go any faster weather you or Casey Stoner are riding it, then arguing about header length, dyno numbers and blah blah blah blah that has beaten like a dead horse all frickin winter.
Well stated..... Track classes are always money well spent! Some one had to say that WR.... |
Rfischer
| | Posted on Tuesday, March 17, 2009 - 02:48 pm: |
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Firemanjim
| | Posted on Tuesday, March 17, 2009 - 03:29 pm: |
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And spend some hard earned dollars on getting your suspension set-up done. More bang for your buck. |
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