| Author |
Message |
    
Art_vandelay
| | Posted on Wednesday, July 14, 2004 - 11:51 pm: | 
|
My timing has been messed around with countless of times. The only thing that helped was the race ecm. I don't get pings on the street anymore. I have run synthetic and larger oil filter from day one. Still looking to pick up an oil cooler. |
M1combat
| | Posted on Thursday, July 15, 2004 - 12:36 am: |
|
I think our best bet would be to take the actual DT's that we would be working with.
I can't quite put my finger on it, but it seems that your equation is leaving out some details as well. I think your equation would only be correct with the bike stationary in still air. I believe that is also the reason why Blake may have said your example is not thermodynamics. I'm certainly not a math major though  (or a physicist).
I think that you may have left out the fact that an air cooled engine has a lot more surface area for cooling as well (before you get to the radiator anyway).
I guess my only experience with this subject (which is what points me in the direction that your equation forgets air flow) is with CPU's and heatsinks. I assure you, if I turn the fan down on my CPU cooler my CPU would overheat and shut itself down in short order. That being said, water coolers do indeed keep CPU's a bit cooler, but at the expense of having a huge EXTERNAL heat sink, a pump, and the mass of the water. I'll stick with my air cooled PC. It's easier to handle when I take it to LAN parties.
I think your equation also leaves out the efficiency in the implementation of the cooling method. With air cooling we are indeed dropping the engine into pretty constant temperature air. With water cooling we are doing that (although we have less surface area and the air tends to come through the radiator first) and running water through small veins in the block and heads. Lets not forget that we are also using oil to cool an engine in the same manner as we would use water...
In any case, I think that the point is that air works as well as we need it to if not a little better, and we don't have to worry about all the other stuff that goes with it. |
M1combat
| | Posted on Thursday, July 15, 2004 - 12:43 am: |
|
Come to think of it... I don't think I've ever heard of an air cooled bike overheating. I have however driven by overheated water cooled bikes on an air cooled bike. I even stopped to chat with one on route 666 to ask if he needed help. I let my bike idle in the heat for about a minute and nothing bad happened. This was a 750 IL4 that I was on. I don't know what the overheated bike was.
I think the reason for this is the fact that as the engine temperature rises, air cooling becomes more and more efficient whereas water cooling becomes less efficient or stays the same (I'm not sure which). In either case, as your engine temp rises, you need your cooling system efficiency to rise as well. |
Wyckedflesh
| | Posted on Thursday, July 15, 2004 - 12:56 am: |
|
~raises hand~ OH OH OH OH I HAVE! I HAVE! My first CB350 seized on a 100F degree day out in the Anza Borego desert. When I came to a stop oil was spewing out the crank case vent cause it was boiling... |
M1combat
| | Posted on Thursday, July 15, 2004 - 01:11 am: |
|
Yikes... That doesn't sound fun at all. I have to ask though... Are you certain that the oiling system was working properly? Could it have caused the overheat? |
Wyckedflesh
| | Posted on Thursday, July 15, 2004 - 01:45 am: |
|
Isn't the oiling system part of the aircooling system? I mean if the oil isn't getting cooled how is it going to keep the rings from seizing? As far as any mechanical faults of the oiling system, none that we could find. That was the original thought but then we didn't realise it was the rings that seized, we thought it was originally a crank bearing that seized. Once the motor cooled off we were able to rock the motor back and forth until the ring broke free. See even aircooled isn't perfect. This was a case of slow speed riding on a hot day with no wind in the upper rpm range due to conditions. Had it been a watercooled machine it would have spewed its coolent before the rings seized. |
Court
| | Posted on Thursday, July 15, 2004 - 05:36 am: |
|
>>>>Isn't the oiling system part of the aircooling system?
Yes, in all air cooled engines.
My old Cessna 172RG had something like 30 quarts of oil capacity and was approved for flight with like 5 quarts.
MOST of the oil in air cooled engines is simply used to move heat to where it can be dissapated.
I'm sure someone can check the above numbers and provide the actuals, I'm out the door for work.
Court |
R1DynaSquid
| | Posted on Thursday, July 15, 2004 - 05:53 am: |
|
Come to think of it... I don't think I've ever heard of an air cooled bike overheating.
I have seen it first hand. 2000 sturgis rally, take 750,000 people & their bikes & try to move half of them down a 2 lane road towards the Buffalo Chip campground. Longest 2 miles you ever have been on. Bikes were overheating & shutting down. Plenty of them just being pushed because they couldnt handle the heat.
2 fellas in front of me, 1 on a Goldwing & the other on a Valkyrie never shut theirs off. |
Court
| | Posted on Thursday, July 15, 2004 - 06:14 am: |
|
So, let's just say it's "VERY unusual".
Accurate? |
José_quiñones
| | Posted on Thursday, July 15, 2004 - 07:03 am: |
|
Art, get the fan kit it helped me out a lot. |
Blake
| | Posted on Thursday, July 15, 2004 - 09:35 pm: |
|
JQ, and cheerleader Dyna,
Erik is talking about the weight of the frame, not the beefiness of the engine which is what I was talking about. And even then he clearly states that the uniplanar mount eliminates the need for a beefier/heavier frame. Try again. |
R1DynaSquid
| | Posted on Thursday, July 15, 2004 - 09:39 pm: |
|
Blake..read it again my friend.
we were able to make the chassis really quite light...barely 200 pounds, which is a very light chassis. If you took an 80-pound engine, that bike would weigh about 280 pounds - really light, as a full street bike
Hmm Erik mentions the frame being light & if he was able to get a lightweight engine it. Notice the "if" for the 80lb engine. |
Blake
| | Posted on Thursday, July 15, 2004 - 09:48 pm: |
|
On overheating... I had a Yamaha that would spew its guts if left idling in the Summer heat, even with the fan coming on.
Art,
Simple heat transfer does not involve any thermodynamics. Thermodynamics involves conversion of various forms of energy to and from heat energy, most often from chemical to heat to mechanical energy (like in a turbine system used to generate electricity or in an automotive engine to generate kinetic energy/motion). When speaking of the cooling of an engine, we are not concerned with any transformation of the heat energy into any other form of energy, only the transfering of heat energy from one mass to another.
How do you cool the water? Does the liquid in a liquid cooled engine see the same delta temperature as the air in an air-cooled engine? How about the air that ultimately cools the liquid in the liquid cooled engine... does it see the same delta temperature?
Your analysis is on the right track, just incomplete. I suppose it would apply to a boat engine with an unlimited supply of cool liquid coolant.
But again, CP is not more important than delta temperature. They both are equally important and of the same mathematical order in the equations for heat transfer. You've proved that yourself.
As to your career, you've got me beat. I've been stuck working as an engineer for the last 18 years. I love it. |
José_quiñones
| | Posted on Thursday, July 15, 2004 - 09:57 pm: |
|
quote:g9: Did the Uniplanar engine mounts allow you to use a lighter frame?
Oh, definitely. Vibration is a real enemy. Even Singles with a primary balancer still have secondary shaking, and it's just really tough on parts. So the only thing you can do is always make 'em a little heavier and a little beefier...Being able to use the Uniplanar-type isolation system, we were able to make the chassis really quite light...barely 200 pounds, which is a very light chassis. If you took an 80-pound engine, that bike would weigh about 280 pounds - really light, as a full street bike, lights and everything.
It's pretty clear he's saying that the engine's vibrations cause it to have to be built heavier and beffier, so the uniplanar isolation system, by keeping these vibrations from reaching the frame/rider, allows the frame and the whole bike to be lighter than a bike using that engine solidly mounted to the frame.
edited by josé_quiñones on July 15, 2004 |
Blake
| | Posted on Thursday, July 15, 2004 - 10:00 pm: |
|
Dyna,
The engine is heavy because it must support massive torque generated by just two massive cylinders. A single cylinder engine producing half that torque would need to be just as robustly designed. Case in point, the Blast engine. Erik mentioned how light the bike would be with a lightweight 80 LB motor to illustrate how light the frame is, not to imply that the motor was over-designed and heavy to handle vibration.
The crank is big and heavy not because of vibration, but because it must endure huge forces transmitted by each of the two big cylinders.
Likewise for the cases and everthing else.
The torque producing power pulse of each cylinder is what governs the structural design of the majority of the engine and what determines how heavy it need be.
Compare the weight of a Ducati air cooled twin's engine to its comparably sized and powered Buell engine. They will be close but with the Ducati having less torque (higher revs create comparable power) it will be lighter accordingly, but not by much. The 90 degree Duc engine is perfectly balanced. Case closed. |
Blake
| | Posted on Thursday, July 15, 2004 - 10:06 pm: |
|
It's pretty clear he's saying that the engine's vibrations can cause it to havethe frame to be built heavier and beefier, so the uniplanar isolation system, by keeping these vibrations from reaching the frame/rider, allows the frame and the whole bike to be lighter than a bike using that engine solidly mounted to the frame.
Please read the question which is being answered...
"Did the Uniplanar engine mounts allow you to use a lighter frame?"
Answer... Yes, by reducing/eliminating engine induced vibration within the frame we achieved a significantly lighter weight frame.
Pretty damn simple. |
José_quiñones
| | Posted on Friday, July 16, 2004 - 07:11 am: |
|
Then explain the logic that says that vibration does not affect the engine in the same way it would affect a frame or any other part of the bike.
When you balance your wheel after putting on a new tire what do you do?
When your handlebars vibrate, what do you do?
If you have a naturally unbalanced engine, and you don't add a counterbalancer (which also adds weight, but it then lets you optimise the engine's parts and make them lighter) what do you have to do to the engine? You have to make it beefier and heavier to stand up to it.
If they made the same torque, the naturaly balanced 90 Ducati twin would still be lighter than the naturally unbalanced 45 degree HD twin simply because its individual parts do not have to resist as much vibration.
Yep, pretty damn simple
|
Blake
| | Posted on Friday, July 16, 2004 - 03:12 pm: |
|
Vibration certainly effects the engine and some of its components, but vibrational loads do not govern the design of the heavy parts like the cases and crank or flywheel, or rods, or pistons, or cylinders.
What would need to be stronger would be any mechanical connections, like head bolts, rocker box bolts, case bolts and such. How much weight would going to the next size bolt add?
When you balance a wheel you are usually trying to obtain dynamic balance through simple static balancing of the wheel, usually by adding weights to the rim. Of course you could also balance the wheel by judiciously removing mass from the wheel and/or tire. I don't see your point.
When handlebars vibrate I look for a loose exhaust clamp. Adding mass to handlebars reduces their natural frequency of vibration making them relatively more comfortable for human hands. Structurally speaking, and you should know this from your mechanics of materials class, lowering a structural member's natural frequency of vibration is rarely a good thing and is almost always a very bad thing, structurally speaking. It can be a catch-22... we seek to lighten the structure to reduce vibration loading, but we beef it up to withstand design loads.
The engine parts are designed based upon worst case stresses and fatigue stress allowables. You seem to me to be saying that the stresses due to vibration govern the design of the major engine components. I disagree. The power-stroke loading and other engine loading cases are what govern the sizing of the major engine components.
Are you familiar with the vibrational environment of the air cooled Ducati valvetrain running up to 9,000 rpm? Your assumption that a Duc engine designed to withstand the same torque as a Buell mill would be lighter is a huge leap based on a guess.
The guy who took it upon himself to redesign the suspension rod joint for that Hyat Hotel thought it was pretty damn simple too. He was wrong.
Bottom line, Erik was talking about the frame design, not the engine design.
We'll need to ask him about the engine design some other time.
|
|
