| Author | Message | ||
     Rocket_in_uk |
With the production 1190 hitting showrooms I am annoyed that the Buell philosophy of Mass Centralisation has not been adhered to with that silencer. I know it's petty, but when Buell has used the Ducati underseat design for years to demonstrate the advantage gained by Buells forever under the engine system no matter the model, this is a U turn which flies in the face of a many years long stand point of Buell's design characteristic and culture. Or design ethos if you will. Rocket in England | ||
| Pwnzor |
I never really saw the big benefit from having the pipe down there... unless you leave the stock pipe that weighs a ton. Aftermarket pipes weigh next to nothing, hell I've got 4 cans on my bike, and they're under 2.5 pounds total. | ||
| Reepicheep |
Weigh the outboard part of the exhaust... that is what will tell you if they aren't centralizing mass anymore. | ||
| Darth_villar |
I was under the impression the only reason the exhaust is high now is to meet export regulations in other countries (Japan I believe). Though I could certainly be mistaken. | ||
| Tq_freak |
after talking to the guys at the Orlando expo about it. its a pretty intricate "muffler" The majority of the weight and "muffling" is still done under the bike, as low as possible and the traditional looking "muffler" out on the side is more of a frequency conditioner to actually increasing exhaust flow. remember the other side of "trilogy of tech" Everything serves multiple purposes. | ||
| Trojan |
The majority of the weight and "muffling" is still done under the bike, as low as possible and the traditional looking "muffler" out on the side is more of a frequency conditioner to actually increasing exhaust flow. 'Frequency conditioner'? yeah right. Was it a salesman you spoke to by any chance? | ||
| Teeps |
I will go out on a limb and say it's for styling. It's what will help sell the bike. | ||
| Reepicheep |
To make big power without making big noise, you need a LOT of exhaust volume. A second outboard can is an easy way to add volume, which gives you more ways to make power. So more volume makes more power. And the EPA and Euro noise tests are fairly specific about what frequencies are tested and objectionable, and which aren't. So again, the additional outboard pipe gives the ability to specifically target frequencies that are problematic for regulatory testing. I can't think of a better term for that then calling it a frequency conditioner. Speaker designers do precisely this every time they build a speaker... they can boost some frequencies and lower others by the design of the enclosure to compensate for non linear speaker responses. The math is not difficult. Exhaust scavanging isn't fantasy, it's a normal part of any modern motorcycle design. So having more exhaust volume to play with absolutely gives designers ways to make more power. I can take my KDX-200 and completely change the character of the power output by putting on an expansion chamber with a 12 inch diameter instead of a 14 inch diameter. It's night and day. I realize a two stroke would make this more prominent, but you can't argue exhaust scavanging doesn't have an impact on power on a modern high performance engine. | ||
| Midknyte |
> Weigh the outboard part of the exhaust... that is what will tell you if they aren't centralizing mass anymore. This | ||
| Tq_freak |
'Frequency conditioner'? yeah right. Was it a salesman you spoke to by any chance? http://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance finds application in internal combustion engines (see airbox), subwoofers and acoustics. Intake systems described as 'Helmholtz Systems' have been used in the Chrysler V10 engine built for both the Dodge Viper and the Ram pickup truck, and several of the Buell tube-frame series of motorcycles. In stringed instruments, such as the guitar and violin, the resonance curve of the instrument has the Helmholtz resonance as one of its peaks, along with other peaks coming from resonances of the vibration of the wood. An ocarina is essentially a Helmholtz resonator where the combined area of the opened finger holes determines the note played by the instrument.[4] The West African djembe has a relatively small neck area, giving it a deep bass tone. The djembe has been used to accompany West African drumming for centuries, making it much older than the knowledge of the physics involved. The theory of Helmholtz resonators is used in motorcycle and car exhausts to alter the sound of the exhaust note and for differences in power delivery by adding chambers to the exhaust. Exhaust resonators are also used to reduce potentially loud and obnoxious engine noise where the dimensions are calculated so that the waves reflected by the resonator help cancel out certain frequencies of sound in the exhaust. In some two-stroke engines, a Helmholtz resonator is used to remove the need for a reed valve. A similar effect is also used in the exhaust system of most two-stroke engines, using a reflected pressure pulse to supercharge the cylinder (see Kadenacy effect.) Helmholtz resonators are used in architectural acoustics to reduce undesirable low frequency sounds (standing waves, etc.) by building a resonator tuned to the problem frequency, thereby eliminating it. Helmholtz resonators are also used to build acoustic liners for reducing the noise of aircraft engines, for example. These acoustic liners are made of two components: a simple sheet of metal (or other material) perforated with little holes spaced out in a regular or irregular pattern; this is called a resistive sheet; a series of so-called honeycomb cavities (holes with a honeycomb shape, but in fact only their volume matters). Such acoustic liners are used in most of today's aircraft engines. The perforated sheet is usually visible from inside or outside the airplane; the honeycomb is just under it. The thickness of the perforated sheet is of importance, as shown above. Sometimes there are two layers of liners; they are then called "2-DOF liners" (DOF meaning Degrees Of Freedom), as opposed to "single DOF liners". This effect might also be used to reduce skin friction drag on aircraft wings by 40%.[5] Helmholtz resonance sometimes occurs when a slightly open single car window makes a very loud sound, also called "side window buffeting".[6] I have built/ Tested some for Freightliner trucks. They work. | ||
| Sifo |
So if it's so bad having an empty, light weight can up under the seat, why does the battery wind up there? The battery has got to be one of the heaviest parts for it's size on the bike. | ||
| Wolfridgerider |
from the EBR website.... In a price per pound weight reduction ratio, this is an excellent value. The EBR lightweight battery weighs in at just 2.05 lbs, compared to the stock battery which weighs 11.55 lbs, for a 9 lb savings, or $41/lb. As a comparison, a titanium exhaust will save 5lbs over stainless, at a typical cost delta of $1000, or $200/lb. This battery is also smaller than the stock unit at 144mm x 69mm x 80mm (5.7in x 2.7in x 3.2in). | ||
| Sifo |
from the EBR website.... Not wanting to debate the pluses and minuses of the lightweight battery, the simple fact is that it wasn't part of what was engineered, or even available when Buell started marketing the mass centralization thing. Those bikes were designed for a 11.55 pound boat anchor tucked up high under the seat. | ||
| Aesquire |
True, but it's also as close to the center as possible. "Mass centralization" is a great concept, but hard to do, you can't put everything in the center, so you compromise. Starting with a given engine, you can move it around, but you can't put a battery in the middle of the crank. There are a bunch of other things to deal with, heat, for example. Can't put the battery next to the muffler, or in front of the radiator, etc. That's why you can see 2 airplanes with the same power plant, very close performance, that look nothing alike. Total drag & thrust are close to the same.... but different compromises.   | ||
| Sifo |
Your whole argument is a canard. Funny thing that a Sportster does a better job of getting the battery near the center of mass. I do recognize that there are many factors to balance though, and I don't think the Sporty is a better overall design. To be fair though, the Sporty and XB didn't have similar design goals. Moving the muffler out from under the engine give a lot of places you can move things. Including the engine. The stock XB muffler is way heavier than it needs to be, especially if you move it up where it won't be used for things like jacking points, or get hit when loading the bike on a trailer. | ||
| Torquehd |
I've always wished they could move the muffler and drop the engine 3 or so inches. It seems like the bikes would benefit a lot from having a lower CG. But I think in doing so, you'd have issues with the outter casings dragging the ground at greater lean angles. Despite what people may say about the blast, the thing handled easily and crisply, and I believe it was due to the extremely low CG. I've considered purchasing another blast to make a fuel efficient commuter... but I just can't live with 30 rwhp. | ||
| Gregtonn |
Torquehd, There is a "sweet spot" on a single track vehicle. Too low and the response is sluggish and slow. Think weeble. G | ||
| M1combat |
This thread is full of stupid. | ||
| Ducbsa |
Honda had a GP bike in the early 80's with the pipes over the top of the engine and the fuel underneath and Freddie Spencer couldn't make it go fast. Since when leaning the bike it rotates around its CG, I would assume there is an ideal location for the CG. As far as the fore & aft location of the CG, road race car designers want it in the middle, which is why mid-engine cars are the optimum. | ||
| Rocket_in_uk |
My point was it seems a little churlish of EBR to detract from their signature exhaust system for a conventional arrangement when clearly what they have had to do for a very high performance twin is do exactly what Ducati have done with their arrangement. Ducati with a great deal more style and elegance it has to be said than EBR. This when Buell used Ducati to show the weight disadvantage of their system in favour of mass centralisation. Just saying  Rocket in England | ||
| Phelan |
Just take note that a couple bolts takes off the secondary side muffler, and that the race bikes have the exhaust exit under the motor still  . I think the streetbikes having the secondary muffler had more to do with emissions and overseas laws than power and weight, etc. They just decided to make it have the added benefit if they were going to put it on for regulations- to have multiple purposes, as mentioned above. I don't think at all that EB is conceding his design principles for others, but simply turning lemons into lemonade . | ||
| Blake |
Centralized mass is about reducing inertia, the resistance to rotation, for a sport bike that mostly means roll. As Greg mentioned, a low center of mass (aka center of gravity or "CG") is not desirable on a Sportbike. The lower the CG, the less agile, more difficult to turn. Before a bike can turn, it must be leaned over, which is accomplished through lateral force acting upon the contact patch of the front wheel. The vertical distance from contact patch to CG is the moment arm through which the lateral force acts to lean the bike. The bigger the moment arm, the easier it is to get the bike leaned over. Somewhere there's an illustration that is better than any words. | ||
| Bob_thompson |
Reading this thread so far I wonder how many racers will be using the mufflers as produced. I believe all will be taken off, where the noise db restrictions allow maintaining the original mass centralization and where noise db's are stricter they will be utilizing a carbon fiber muffler that weighs a negligible amount and not detract from handling. And I do not see any mufflers on the two HERO bikes of Geoff's and Aaron's. Does anybody have info on WSB and AMA regulations on noise? Many street buyers of the new 1190's will probably want something good sounding and I love the sound of my 1125R as in this link: "www.youtube.com/watch?v=rD14y2EVCw4" Yes I'm an old school biker and love great sounding bikes. Forget the EPA noise police. Its still a free country, I think, at least here in the free state of Utah. | ||
| Blake |
I too was disappointed to see the conventional looking "muffler". You have to know that if Erik and associates can find a way to maintain engine performance while ditching the side can/chamber, they surely will. | ||
| M1combat |
You're close with CoG height Blake... kinda... But higher isn't "better" without an explanation. The "right" height relative to rake, trail, bar length, rider strength, tire width and profile, optimum tire lean angle capability among a few other things is better . Think of having the CoG height 10' above the bike... You'd have to drive a good deal of distance laterally out from under it to achieve a given lean angle. Having it inches above the contact patch would require a great deal of force at the contact patch to initiate and stop the lean angle. Also... The lower the better for acceleration and braking, but obviously corner speed is somewhat (not to the extent that you forgo acc/brake performance for sure) more important in racing. Mass centralization is significantly more important that outright CoG height in any case once the CoG height is pretty close to where you need it. Also... A lower CoG will require slightly less lean angle for a given cornering force AND a given tire width AND lean angle. The wider the tire, the higher the "right" CoG location will be. this may be why taller riders have done well on race bikes with modern width tires. The combined CoG height is much more important that the CoG height of the bike, but the "right" spot is still a specific location given a specific transient situation. As I'm sure you know it's all a balancing act between different aspects of geometry. For the record... The pictures that explain this better are located in "Motorcycle Handling Chassis Design Manual" by Tony Foale (Message edited by M1Combat on February 22, 2014) | ||
| M1combat |
One more thing... I'm pretty sure the CoG of the RX is "about right" and I'm also pretty sure that EBR didn't put the extra exhaust on there because they wanted to. I'm sure they did it for compliance of laws and they fully expect to not run them on the race track and I'd think they fully expect the consumer to know exactly what to do with them. | ||
| Sifo |
and I'd think they fully expect the consumer to know exactly what to do with them. Engineered to do multiple things... Meets EPA compliance and holds papers down on your desk? | ||
| Blake |
Hey Don, You're right about CG location and the other considerations related to it. Tony Foale may offer some good information, but his understanding of motorcycle steering dynamics is just plain wrong when it comes to gyroscopic effects. (Message edited by Blake on February 22, 2014) | ||
| Torquehd |
I purchased and attempted to read a Tony Foale book. A chapter into it, I decided to wait for an English version to be released. Unfortunately, physics and kinematics, at the engineering level, require a college degree. Perhaps someday... | ||
| M1combat |
How so? |
