| Author | Message | ||
     Shea |
Wish I would have noticed it earlier, but today I just realized that the October issue of cycle world printed wrong specs on the 1203 engine in the Ulysess. They rated it at the 900 engine specs and stated it was 481 lbs dry weight. Where did they get that number? I sent them an email, but I think it's too late now. Oh well... | ||
| Natexlh1000 |
You mean the 80hp? I think they might have measured it on a real dyno at some altitude above sealevel. Generally, 15% of your power will be eaten by your drivetrain before it gets to the street. | ||
| Shea |
It was rated in bhp, not whp. | ||
| Blake |
Cycle World's "dry weight" is totally different from what almost all manufacturers list as "dry weight." Except for Ducati, most all the manufacturers' listed "dry weight" is really the old shipping weight which excludes not only gasoline and oil, but also the battery. The CW "dry weight" only excludes gasoline. Brake horsepower (BHP) may be measured at the rear wheel. Doing so simply requires a "brake" type rear wheel dynamometer. I believe that the Dynojet 250 is capable of brake RWHP measurements. Typically though, rear wheel HP (RWHP) is measured in inertial mode or on a purely inertial dynamometer. The Dynojet 250 is primarily an inertial dynamometer. The CW HP is low due to a problem with the interactive exhaust valve. They should have corrected that since their last test. It appears as thought they simply re-used the old test data and forgot to explain the low HP results. | ||
| Blake |
The difference between inertially measure HP versus using a brake method is that the brake method can hold the engine speed more constant and thus prevent inertial losses in the engine from affecting the results. With all else being equal, brake type HP testing will yield higher results than inertial type HP testing. | ||
| Court |
There is nothing MORE CONSISTENT than measuring motorcycle "dry weight" It's ALWAYS been confusing. . . . and likely will as long as the population of participants includes govvies chanting one thing, owners another and manufacturers another. | ||
| Blake |
"govvies"? | ||
| Blake |
If my red dinner wine is "dry", and if napthalene is used in "dry cleaning", couldn't gasoline be logically included in a "dry weight"? Sorry, that may be a lame attempt at too much dry humor. I should probably put a damper on it. ![: ]](http://www.badweatherbikers.com/buell/clipart/proud.gif) | ||
| Shea |
LOL at this thread. Since when was brake horsepower a measure of the whp? Wikipedia "Brake horsepower (bhp) is the measure of an engine's horsepower without the loss in power caused by the gearbox, generator, differential, water pump and other auxiliaries" | ||
| Blake |
That Wikipedia definition is wrong. Simple as that. | ||
| Blake |
To clarify: One may measure the HP at the crankshaft using an inertial dynamometer, in which case it would not include losses from the gearbox, etc and would not be "brake" HP. One may also measure the HP at the rear wheel using a brake dynamometer, which would include the losses from the gearbox, etc, but would indeed be properly specified as BHP. "Brake" and "inertial" are terms that describe the type of dynamometer used to measure the HP. One also needs to specify the location of the measurement, "rear wheel" or "crankshaft" for instance. The confusion developed because in the past and still today the vast majority of rear wheel dynamometers employ the inertial method, but some also provide a brake operation as well. | ||
| Jlnance |
There is nothing MORE CONSISTENT than measuring motorcycle "dry weight" Why does anyone even care about the dry weight. It's not like they get ridden dry. | ||
| Shea |
I have never seen bhp used to describe wheel hp. http://answers.google.com/answers/threadview?id=426996 "There are many different ways of measuring the power of an engine. Brake horsepower is a common term and refers to the power measured at the crankshaft using a "prony" brake." http://www.answers.com/topic/horsepower http://www.automotiveforums.com/vbulletin/showthread.php?t=263914 http://en.wikipedia.org/wiki/De_Prony_brake Seem everyone is wrong. (Message edited by Shea on September 13, 2006) | ||
| Blake |
Shea, Yes. They are wrong. I don't know what else to say. | ||
| Diablobrian |
I agree with Blake. It would be far more accurate to use the terms "motor dyno" and "chassis dyno" to differentiate where the reading is taken. Then denote what type of dyno was used to obtain the results. I guess that's not fashionable these days though.  (Message edited by diablobrian on September 13, 2006) | ||
| Shea |
Any time I read these rags, they always seem to be posting crank hp, so I don't understand why they would print anything other for the Buell. The rest of the bikes seem to be correct according to all other sources, so the Buell is the only one off. You are right though, it would clear alot up had they just post Crank or Wheel horsepower or something more exact. just to add, I hear these terms used on alot of Euro based programs and a few US shows too. I know that the Euro shows are talking about crank power, but not sure about the US ratings now. (Message edited by Shea on September 13, 2006) | ||
| 1313 |
water pump Alright Shea, Just what in the world are you holding back from us?!?!  Spill yer guts! 1313 | ||
| Tripp |
brake hp is widely used as a measurement for electric motors. never heard it used for motorcycles till now. | ||
| Blake |
The type of HP measurement has little to do with what motive device is being measured. It seems logical that since most electric motors are not installed in cars or motorcycles as propulsion, they are tested not on chassis dynamometers but simple bench type or motor dynos. Again, "brake" refers to the type of dynamometer being used to measure the power. A "brake" dyno uses... you guessed it, a brake of some sort in order to measure torque. Actually they measure force applied to a given known moment arm. Actually they measure the changing electrical resistance in a known/calibrated strain gage. Anyway, you get the point... a brake dyno uses a calibrated brake of some sort to resist and measure applied torque, be it a brake using water, eddy current/electrical, or just a plain old drum or disk brake. A water brake dyno is referred to as a "pump". It is not uncommon to hear someone in the field refer generically, even to an inertial chassis to a dynamometer as a "pump." | ||
| Shea |
I'll take your word for it. I don't have first hand knowledge of this stuff, only what I read. For people like me though, they should be specific. This is def a learning experience. I sent them an email about it, I'll post if they reply. | ||
| Blake |
I agree, they should be specific. Unfortunately a lot of the journalists writing about dyno testing are not clear on these issues. | ||
| Blake |
Ever hear of BMEP?  | ||
| Aesquire |
Brake mean effective pressure? You are right about the brake hp measurements. "brake" dynos measure brake hp. Wikpedia is a slow news forum. Not a good reference source. The entire world is lousy peer review. For instance, what do most people know about neutron cross section? Or why it is important to some applications, and not others? | ||
| Skully |
I should probably put a damper on it. Or would that be dampner?  | ||
| Jimidan |
Maybe a Dampner Masters? jimi | ||
| Shea |
Aesquire, If that is the case, then why would someone invent a device to measure power, then call that process by a specific term, then suddenly everyone just takes it upon themselves to assume it's something else? Wikipedia gave the REAL definition to a word, but because people have just took it upon themselves to change the meaning, it's Wikipeia's fault not to go along with the trend? | ||
| Blake |
Ignorance. "then suddenly everyone just takes it upon themselves to assume it's something else?" Not sure what you are talking about, but there was no "suddenly" about it. It is just goofed up ignorance which became convention is all, kinda like the old "synthetic oil will cause bearings to flat spot" or "air-cooled engines are doomed due to ever more strict anti-pollution regulations" or "torque at the rear wheel." How many times have you seen that term spoken, "torque at the rear wheel", Cycle World and most all the motorcycle publications use that term and it is 100% dead wrong. The torque reported in a dyno test is at the crankshaft. It may be referenced to the rear wheel in that it accounts for drivetrain parasitic losses, but it is the torque at the crankshaft. Wikipedea is a public input opinion site. Most often the information is pretty accurate. Sometimes it is not. Sometimes the myths and conventional misinformation make their way into the site. It is not at all surprising. You should post a correction. | ||
| Blake |
Question: Besides the method (brake versus inertial) and type (engine/crank versus chassis/rear wheel) of dyno measurement, what else do we need to know in order to better understand dynamometer test results? I can think of one very important parameter, maybe two, depending upon the type of dynamometer used. | ||
| Blake |
Is there another type of dynamometer or method to measuring HP for a vehicle? I think there is. In fact, I've often thought of purchasing one. Do you know it? | ||
| Shea |
Blake, I have no idea what you're talking about. Please post what you have in mind. | ||
| Diablobrian |
I think he's referring to an accelerometer which, with accurate mass figures for vehicle and occupant, can give some fairly accurate data. Those are getting more affordable and smaller all the time. | ||
| Blake |
Brian nailed it! What is the popular brand called, bike dyno or something like that? | ||
| Shea |
Ahh, I have an accelerometer for my cars. I'd say that it's fairly accurate in the 1/4 mile, maybe .2 seconds off, but for 0-60, it is not as accurate. It was saying my Trailblazer SS was doing 0-60 in 5.3 seconds and coming up a little early. It nailed 60mph once and showed me a 5.8, which i know is accurate. It doesn't have the horsepower option on it, but does give G-force. | ||
| Aeholton |
I think Veypor makes a motorcycle specific one. | ||
| Court |
The good thing, and it's seldom discussed, is that VERY FEW people who own or ride motorcycles ever read any of the motorcycling publications. I was floored when I first read the numbers. Those of us who are bitten by the bug wouldn't think about subscribing to everything we can get our paws on. But, I think less than 30% of folks who bikes ever read a motorcycling publication. One of the reasons you'll see more ads in things like GQ. Frankly Babs . . . most folks don't care. | ||
| Davegess |
Wikpedia is a slow news forum. Not a good reference source. Ain't that the truth. I take anything I read there with a big grain of salt. People have deliberatly post false and damaging information about individuals, products and companies on that site and the material has stayed up for days if not weeks before it is taken down. I would not rely on it for any thing serious. | ||
| Blake |
Shea, The devices I'm thinking of are not just an accelerometer, but also a software and data logging device that will record data and report HP and engine torque. Of course one must input all the correct information such as the weight of the vehicle plus rider/driver. And it is most likely not accurate for higher speeds where aerodynamic drag become significant. Not sure if they include correction factor capability or not. But if not, as long as one knows the ambient conditions, one can apply the correction factor via spreadsheet. A good accelerometer should be extremely accurate. | ||
| Aesquire |
Once upon a time, a Meter ( the basis for metric measure ) was a fraction of the circumference of the Earth, then a platinum bar in a vault in Paris, then a multiple of a wavelength of a certain color light. It's about the same length, any way you get there. Sometimes the references are wrong. The U.S. Armed Forces entrance test once said the Mars was the closest planet to Earth. They were wrong. They also did not appreciate a snot nosed high school kid correcting them. Really didn't. I read some bike mags, sometimes I lay off, but I usually enjoy the hyperbole & tech articles. Where else would I learn about "the pace" or countersteering? Sure, most is advertising drek, but as Sturgeons Law states, "95% of everything is crap" | ||
| Shea |
Blake, I don't know of any motorcycle devices, but G-Tech has out an RR and SS model. The RR has the data logging feature and many other things (hp and Tq estimate). There was a review that I read that compared the device to a $3,000 model that they use that uses GPS and they said it was one of the most accurate units they have ever used compared to the GPS unit. I just have the regular G-tech pro. http://www.gtechpro.com/rr.html Not bad for $300 either. |
