| Author | Message | ||
     Sarodude |
Maybe a whole bunch of posts should be moved here... Some reference has been made to Posrche's air cooling and how they had powerful and reliable motors. They aslo had the mother of all fans blowing a crapload and a half of air through the shroud, baffling, etc. I helped my brother in law rebuild his 911 but don't remember if there was a thermostat and shutters like the aircooled VWs... The bottom line is that truly effective air cooling SEEMS to need more than an accidental supply of air approximately running around the critical areas of the engine. I don't believe that air cooling for the sake of air cooling is a good thing. The visual clutter, complexity, and increasing number of things to go wrong would seem to reduce the attractiveness of sophisticated air cooling - at least as it relates to naked lightweight user friendly bikes. Ya might as well hang a radiator off the thing at that point - aesthetic heresy for a naked bike. I don't really know for sure, but I'd suspect the true benefits of water cooling lie in a greater ability to keep engine temps CONSTANT. Don't air cooled motors tend to be put together kinda loose? If so, is the looseness to allow for different clearances given the wider range of operating conditions? Does that looseness extend all the way to the point where sealing combustion may be compromised? I've really come to appreciate the simplicity and benefits of air cooling - especially as it relates to bikes. However, I do believe there's a reason why all the super high (sustained) horsie motors out there resort to water cooling. You want a water cooled Buell? I'd sure as hell hope it'd be fully faired 'cause I don't want to see a radiator. It's like the refrigerator repairman's butt crack. -Saro | ||
| Hootowl |
Except you can't use it as a pencil holder... | ||
| Blake |
Saro, good one. I will use that one myself when the chance presents itself. Still, you'd think the radiator could be more creatively integrated into a motorcycle. The RC51 does a nice job. As does the Bimota superbike (radiator under tail section right?). How about this... Get rid of the need for cooling and forget about the whole issue. Ceramic engine, alternate fuels. That's my way of thinking outside the box.  | ||
| Sarodude |
Blake- You mentioned ceramic engines. My ear hasn't caught mention of that concept for some time. Isn't anyone developing that technology? I agree about radiator integration. I think the Honda NAS concept hid the rad under the tail as well - and call me a Communist but I kinda like that bike... -Saro | ||
| Hootowl |
I read a few years ago (like 10 or 15)that there were problems with ceramics. None that couldn't be resolved, but that no one wanted to deal with at the time. Ceramics are abrasive, and you'd have to use something besides oil to lubricate it, like teflon coatings on everything. I don't remember most of the article, but that was the main point. They were talking about engine temps in the 1000's of degrees. Not sure I want that next to my leg. I'd be interested to know whether any progress has been made in this area. | ||
| Sarodude |
Hopefully they'll get the pencil holder thing resolved as well... -Saro | ||
| Anonymous |
I agree that H20 cooling is better. Unfortunately for a motorcycle carrying the water, radiator, water pump and associated hoses adds a lot of clutter and unsightliness. In our favor we have an exposed motor that might tolerate heat a little better (Powered by the same engine the Ducati Monster S4 has a radiator 1/3 the size of that in a 916). W/o water cooling compression has to be set lower and peak power cannot be sustained. Since we are not racing, street use allows us to use a power burst and then allow the engine to settle before our next flogging. | ||
| José_Quiñones |
I think the Britten was the first bike to put the radiator under the tail The new Bennelli Tornado also has the same setup, with TWO fans in the tail to keep the airflow acceptable. | ||
| Davegess |
American Rider has a story on the HD NOVA bike and it has the radiator under the seat. I will try and scan it later Dave | ||
| Rick_A |
I just dig the simplicity of air cooling. Everything else is secondary. Bikes look best naked and without that mess. I just like machines with the least amount of components/complexity as neccessary. That's part of why I'm gettin' rid of my Camaro and souping up an old VW Beetle sometime in the future...the other reasons are high insurance and a gas guzzling engine. | ||
| Blake |
Not all ceramics finishes are abrasive. Coatings exist that result in extremely smooth ceramic finishes. Ever notice how smooth your coffee mug is, what about a toilet bowl? Not up to engine part spec, but the principle is the same. How about a carbon fiber reinforced ceramic connecting rod that weighs 1/4 of our standard steel rods? Could be possible? | ||
| Mikej |
It's the glazing on the ceramic of cups and bowls that's smooth, not the core material. Take off the glazing and you basically have a sieve. 20+ years ago circle boat racers were ceramic coating their piston tops, neat stuff. My thinking is that composits is where the current trend is. Is Nikosil (sp? name?) a composite? Maybe I'll have mom fire me up some pistons in the kiln this weekend. ===== Oh, wait, that's what you said,... "nevermind". | ||
| Hootowl |
They are smooth to the touch, but you can sharpen a knife on the edge of a toilet. They still present an abrasive surface to metal. Maybe there are better examples of non abrasive ceramics, I don't know. Like I said, this was 10-15 years ago. Oh, and coffee mugs and toilets are glazed and fired to make them look like that, they're not just raw ceramic. Would the paint hold up to the beating it would receive in an engine? Besides that, I don't even think it's the same material. They were talking about ceramic metals, not ceramic pottery. I don't know what the difference is, but I know that whatever they make coffee cups out of isn't strong enough to be a piston. Whatever. I'm sure they can figure it out. If that means coating everything with teflon or nicasil or a combination of the two, so be it. I just haven't heard anything about it since I read that acticle all those years ago. | ||
| Spiderman |
Hoot, Posrche uses ceramic brake pads and rotors on all there high end production cars and the company that produces it sells the upgrade for almost 10,000$ and they are garanteed to not heat up (too much) or ever wear out. | ||
| Hootowl |
Just googled for ceramic engines. The material of choice these days is Silicon (Si2) which apparently doesn't suffer from friction problems. In fact, they claim there are no lubricants in the engine. It isn't cast like a toilet though. It is compacted at high pressure, stintered and cured, then it's machined into parts. No oil. That just blows me away. | ||
| Hootowl |
Are they ceramic or carbon? I've never heard of ceramic brakes, but that would go along with the abrasive ceramic theory. I think we've all figured out by now that the term "ceramic" describes a number of materials. The Si2 based ceramic in my previous post would not make very good brake pads if it's as slick as the article claims. | ||
| Hootowl |
"Ceramic materials are inorganic, nonmetallic materials. Most ceramics are compounds between metallic and nonmetallic elements for which the interatomic bonds are either totally ionic or predominantly ionic but having some covalent character. The term ceramic comes from the Greek word keramikos, which means burnt stuff, indicating that desirable properties of these materials are normally achieved through a high-temperature heat treatment process called firing" | ||
| Hootowl |
Lots of info here on ceramics. | ||
| Blake |
Oh brother. Hootowl. Try reading my post AGAIN. 
 I don't think so. | ||
| Mikej |
Actually, yes you can. You can also sharpen a knife on a stick of wood, just ask any sideshow huckster selling steak knives.  | ||
| X1glider |
Even if you could, Anyone who sharpens a knife in that manner while sitting on the can is asking for BIG trouble.  | ||
| Mikej |
Only if you try to sharpen the knife on the inside edge of the bowl.   "Medic!" | ||
| Hootowl |
Blake, did I miss something in your post? Are we saying the same thing in different ways? When you get home, rub a knife on the toilet seat and see the streak left behind by pieces of metal being worn off of the knife. I'm not making this up. | ||
| Hootowl |
"How about a carbon fiber reinforced ceramic connecting rod that weighs 1/4 of our standard steel rods? Could be possible?" At the temperature a ceramic engine operates, the carbon fiber would burn. | ||
| X1glider |
The 10k optional Porshce 911 brake rotors are an aluminum-silicon oxide (matrix? composite?) material which has a much higher coefficient of friction, less weight, extremely rapid dissipation of heat and excellent dimensional stability. Because of that, the diameters can be smaller as well, further reducing weight. I've heard in the neighborhood of 5 lbs. each. for a front vented design. They probably go thru pads pretty damn quick tho. But if you can afford a 911, you can afford new pads too. | ||
| X1glider |
Don't forget, carbon fiber, is just that..."carbon", not "carbon and cotton thread", but that does exist also among many other types, depending on the application. Carbon has a melting point of 3652^2 celcius. Still think it will melt? Carbon fibers do look like thread but it is just bonded chains of short or long strands of carbon molecules depending on the loading characteristics needed. | ||
| X1glider |
I should probably clarify that what would melt in CF is the bonding agents. Ok, Blake, since you were challenged directly, you try the knife thing and get back to us. Like Mike said, don't use the inside of the bowl or I won't be seeing you at OHR this weekend!  | ||
| Xgecko |
Ceramic's make great knife sharpeners I finish the edge on all my knives with a piece off a AIM-54 nosecone  It does a great job | ||
| Jim_M |
but is it a sharpener? I know they make great stroppers, but to actually sharpen? Leather makes an excellent stropper as well, but it won't sharpen worth a damn  | ||
| Jrh |
The Yamaha R1 uses what they are calling a "ceramic-composite" coating on there cylinder bores. | ||
| Hootowl |
Remember folks, "ceramics" means "burnt stuff". There are many types (see links above) The Si2 stuff is apparently slicker than snot. The ceramic that toilets are made of is not. Carbon melts? Maybe in a vacuum. Wouldn't it burn (I did say burn, not melt) long before then? Is the carbon in carbon fiber fundamentally different than the carbon in coal? Is it a carbon compound? I'm asking. I don't know. Carbon can take many forms, like this Buckey ball. This particular form is highly stable and doesn't react with much. Something to do with the shape of the molecule and that the shells are satisfied by the electrons in the other carbon atoms. Do the carbon chains in carbon fiber somehow keep it from oxidizing? | ||
| Hootowl |
CARBONISATION(GRAPHITISATION) involves heating the fibers up to 3000 ° C in an inert atmosphere, the fibers are now nearly 100 % carbon. This is somebody's personal page, but it seems to have a good bit of info on CF if you scroll down a bit. | ||
| José_Quiñones |
Amazing what a little searching will find! Thanks Dave Gess! U.S. Patent Office Type in 4,445,587 in the query Then type in 4,530,315 in the query Have fun, there will be quiz later! | ||
| X1glider |
The basic materials used to produce technical ceramics are extremely pure oxides, nitrides, carbides, borides and silicides and metals such as aluminium, zircon and titanium. So, ceramics don't start out as "burnt stuff." The metals are crushed and ground into a fine powder and are then burned at temperatures of up to 3,000 degrees Celsius. You end up with a high-performance material which is many times more dimensionally stable and resistant to heat and chemicals. All that is left is to apply it, usually by embedding it by shooting it thru a nozzle at mach 2. There are many forms, abrasive and non abrasive, but it's advantages are in it's abilities to handle heat and chemicals as opposed to structural strength, which is where carbon loading comes in. Ceramics have too low a density to be strong. Ceramics such as Zirconium Phosophate are good up to 2800 deg F and Alumina is good between 2700-2900 deg F. The Yamaha cyclinder coating makes wonderful sense. It is extremely durable and slick, unlike the toilet grade ceramic. (Guess that explains the skid marks.  )The extremely thin coating transfers heat to the aluminum walls faster than an iron sleeve would and the aluminum can better do it's job by tranferring heat to the water jacket. Only problem I see is what if you wanna go BIG BORE? Who will re-coat it? Carbon melts? Sure. At 3652^2 deg Celcius or 24,006,819 deg F I would say it does. Look at a diamond which is carbon. It's crystalline structure changes under heat and pressure, but did it actually melt to do it? I doubt it, most likely it was just forged, but the heat was indeed high. The buckey ball...will not oxidize. It is a solved chemical equation with no open valence rings (it take 4 carbon molecules to solve the equation) so it is indeed pure and no ther molecule can attach themselves. It was always carbon, unless they are speaking of the resins are turning into carbon. Couldn't tell. What they are doing is essentially heat treating which changes the structure (graphitizing implies a change in structure even tho it's still carbon). So carbon can take any heat an engine can throw at it plus it's strength to weigh ratio is unmatched. It has excellent dilectric properties too, so it does shed heat. I posted elsewhere of a CF NASA uses with 3 times the thermal conductivity of 1000 series aluminum. Mercedes is testing ceramic valves as we speak...1/2 the weight and therefore allows the use of lighter valve springs, collars and retainers. Perhaps we'll live long enough to see ceramic engines in our bikes. But one step at a time. Valves would be a good start. And CF cases, manifolds, oil tanks and connecting rods would be feasible too. The oil doesn't exceed 300 deg F. Is there a point to all this techno discussion? Just that don't write off ceramics and composites for engine use. But the price will prevent us from seeing it in the next 10 years at least. Maybe water cooled will be a thing of the past. Maybe we'll be riding electric bikes and it won't matter anymore. |
