| Author | Message | ||
     Rick_A |
I changed to Mobil 1 gear oil...I got smoother shifting, less noise, and a leaky primary. I'll be replacing a couple gaskets and no doubt some components while I'm at it. Automotive energy conserving oils can lead to premature clutch failures...and lack "extreme pressure" additives that protect meshing gears . | ||
| 99x1 |
I tried automotive Mobil1 15W50 in the primary because I understood a previous thread on the new HD synthetic indicated using OEM synthetic 20W50 in both the engine and trans was OK. Clutch works OK - just in neutral with the clutch out it sounds a touch louder. Looking through the thread, the viscosity of SportTrans is 100, Mobil1 75W90 is 106, and 15W50 Mobil1 is 125. (WAG): Because it is thicker it is causing more gears to rattle in neutral? I will put Mobil1 gear oil in next - thought it would actually be a worse choice for the wet clutch. Thanks; John | ||
| Ara |
I switched from SportTrans to Mobil 1 75W90 gear oil and noticed no appreciable difference in shifing or noise. | ||
| Djkaplan |
"How do the cooling fins on our cylinder work?" There is no insulating boundary layer of stagnant oil in a cylinder. "I don't see a film of oil acting there as much of an insulator." The oil does not isulate the inside of the tank, it insulates the volume oil itself from being cooled efficiently. This is not my theory, Blake. It was gleaned from many sources, the main ones being P.E. Irving's excellent books on engine design and the fluid dynamics courses I took while studying mechanical engineering. If what you say is true, then the oil pans of every wet sump engine and the oil tanks of every dry sump system would have cooling fins to take advantage of the relatively inexepensive and easy way to increase surface area and heat transfer. Such is not the case in any modern automotive, motorcycle, or aeronautical application. If a finned oil sump truly had any benefits, designers would have found a way to place them in a cooling airflow. It would have been much easier and inexpensive than adding a relatively difficult to manufacture external oil-cooler. Except for pure stylistic exercises, this is not the case in any production, racing, or industrial application, situations where simplicity and efficiency dictate design. P.E. Irving, Motorcycle Engineering. 326 pp., Los Angeles, CA, Clymer Publications, 1973. P.E. Irving, Motorcycle Technicalities. 97 pp, Sydney, Turton & Armstrong, 1973. P.E. Irvine, Tuning for Speed: How to Increase the Performance of Motorcycle Engines for Touring, Racing and Competition Work. 6th edn., 260 pp., Sydney, Australia, Turton & Armstrong, 1987. | ||
| Blake |
DJ, Warning... Heat Transfer was one of my all time favorite topics.  Do the cylinder bores not support a film of oil? How thick is the boundary layer of oil in an oil tank with hot oil circulating and sloshing around compared to the film thickness developed on the cylinder bores or compared to that within the tubes of an oil cooler? Your references notwithstanding, you may be jumping to conclusions. I think that your assumptions and/or information about why most engines typically do not have cooling fins on their oil reservoirs may be mistaken. Oil reservoirs typically do not have cooling fins, not because they would not aid in cooling, but because they don't need them and because they can actually be highly detrimental to the oil and the operation/efficiency of the engine. Mission one of engine cooling is to keep the critical engine parts and the oil within prescribed operating temperatures. Too much cooling of the oil prevents it from reaching optimum operating temperatures leading to a significant drop in engine efficiency and the accumulation of undesirable moisture and acidic compounds; thus you'll find no oil coolers or fins on the oil reservoirs of most commercial engines. Most engine cooling systems provide virtually all of the cooling the oil needs to keep it and the engine within the proper operational temperature range. Only in engine designs that rely significantly on the oil to carry heat from the engine does special oil cooling become an issue. In those cases the oil is acting as a primary agent for the tranfer of heat out of an engine. A properly designed oil cooling system will most often include a thermostat to prevent or limit cooling until it is actually desirable (when the oil becomes overly hot). A finned oil reservoir could indeed easily provide effective cooling of the oil, but that configuration can be very detrimental in that such an oil cooler/reservoir cannot be bypassed; it will always try to draw heat from the oil. Therefore, fins on an oil reservoir are not undesirable because they would be ineffective. They are undesirable because they would provide continuous, uninterruptable cooling, even when such cooling would be highly undesirable like upon start up and in cold ambient temperatures. The cylinders have fins to aid in the convective heat transfer from the metal cylinders to the ambient airflow. The fins provide added surface area through which heat can be transferred through convection from metal to air and also through radiation to the surroundings. Now, apparently, the new Buell XB9 engine, enveloped by frame and airbox, requires the help of the oil to cool the engine. The exposed interior surface area is as important as the external. Relative to their capacity oil coolers provide a HUGE internal surface through which the oil can transfer heat and an even greater finned external surface area through which the air can draw heat from the cooler. Suppose the oil cooler's cooling passages have a capacity of 4 onces (1/8th quart) an internal surface area of 20 square inches and an effective external surface area of 40 square inches. If we assume that we have a 3 quart total oil capacity for the engine/reservoir/filter, the oil cooler represents 1/24th of the total oil system capacity. The equivalent surface area corresponding to the total capacity would be 480 square inches (24 times 20 sq inches). Comparitively, the oil tank would hold roughly 2.5 quarts (5/6 of the total oil system capacity) with an interior and exterior surace area roughly equivalent at around 300 square inches (guesstimate) for an equivalent total capacity surface area of 360 square inches (6/5*300). That's not too far off from the total capacity equivalent volume of the oil cooler. In other words, with the addition of some fins and vigorous airflow, the cooling potential of an aluminum oil tank could be comparable to that of an oil cooler. It's not that the insulatory effect of a well developed boundary layer does not affect the efficiencies of heat exchangers, it's just that oil reservoirs are devoid of fins for a totally different reason than the one you offered. | ||
| Ryan_M2 |
Various automotive manufacturers have used finned oil pans. My 1987 Porsche 944 has a finned aluminum oil pan. Shelby used them on some of his cars in the 60's. And some current V6 Japanese cars apparently have finned oil pans as well. | ||
| Ara |
OK, so my original idea wasn't so original. :-) Question is, would bonding some fins onto the oil reservoir be worth the trouble? And is there a bonding material (JB Weld?) that will transfer the heat from the reservoir to the fins? (I doubt anybody with a pretty alloy reservoir would want to risk welding fins onto it.) I'm pretty sure that Radio Shack sells aluminum cooling fins of different sizes. | ||
| Sarodude |
Russ- Electronics might be a place to start looking for heat conducting adhesives. I know from my PC hotrodding that thermal greases or adhesives are necessary to get a heat sink to optimally leech the heat from something like a CPU. However, best practice is to use AS LITTLE AS POSSIBLE as it will not conduct as well as the heat sink. Some people go so far as to lap the CPU and the heat sink on a flat plate to get the surfaces to really like each other with a minimum of goop needed to fill in the microscopic gaps. I don't know too much about the subject other than this anecdotal stuff. -Saro | ||
| Djkaplan |
"Do the cylinder bores not support a film of oil?" The film of oil left on a cylinder bore after being scraped by the rings is too thin to become an insulating boundary layer. Oil pooled in a sump is a different situation. "In other words, with the addition of some fins and vigorous airflow, the cooling potential of an aluminum oil tank could be comparable to that of an oil cooler." I disagree (respectfully) for the reasons outlined in my earlier post. There would be some benefit, but they wouldn't be nearly as effective as an oil-cooler. The fins would be of greater benefit in an area where oil was splashed on the inside surface, not pooled. "My 1987 Porsche 944 has a finned aluminum oil pan. Shelby used them on some of his cars in the 60's. And some current V6 Japanese cars apparently have finned oil pans as well." Not familiar with the 944 sump, but would be willing to be that fins on an aluminum oil pan are there mainly to increase structural integrity. We can go back and forth on this as much as you want. The topic has been broached many times in many discussions in the past, and the answer is always the same. This very issue was discussed by Kevin Cameron years ago in his TDC column and he also came to the same conclusion. I'll see if I can dig up the article because this is what pointed me to P.E. Irving. I am certainly not clever enough to have developed this argument myself, but I am willing to do the legwork and track down references that will support my explanation. Will be back with more specific references and information. | ||
| Ara |
To me, this discussion boils down to a matter of volume vs. surface area. That having been said, putting cooling fins on the oil reservoir would not be entirely ineffective, just less effective than a purpose-designed oil cooler. It could be just enough in certain climates, and certainly insufficient in others. | ||
| Jmartz |
I've always though of cutting grooves to increase surface area in the immediate vicinity of the exhaust valve. Perhaps we could run more compression (with reduced chance of detonation) if the top of the cylinder head was modified to transfer more heat to the oil. The oil could then be taken out to a cooler before recirculating back into the engine. | ||
| Blake |
DJ, You totally ignored the crux of my point. That cooling fins on an oil reservoir are undesirable not because of the effects of an insulating boundary layer, but because such a reservoir would render continuous, possibly detrimental cooling to the oil whether it was desired or not. Also, your use of the term "boundary layer" with respect to a volume of oil in a tank/reservoir is misleading and in truth incorrect. The only way a "boundary layer" can form is through the mechanism of steady laminar flow. I don't see that condition existing inside an oil reservoir, especially that of a Buell motorcycle where oil is being vigorously circulated and sloshed all about as the bike travels down the road. You disagree with that? The boundary layer in laminar fluid flow hinders convective heat transfer from the fluid to the wall/surface of its container; the boundary layer has absolutely no effect on the conductive heat transfer within a homogeneous fluid or from the fluid to the wall/surface of its container. Is oil significantly conductive (more like water), or is it insulative (more like air)? Which mechanism of heat transfer governs the rate of heat transfer between oil and its aluminum container? If the film of oil on the cylinder bores does not act to significantly insulate the cylinder surface, how thick must it be before it does begin to significantly hinder the transfer of heat? How does an aluminum piston shed heat and avoid exceeding its critical operational temperature? Does some of a piston's absorbed heat from combustion get transferred through the film of oil and into the cylinder wall? Interesting stuff. It's not theory; it's the basic science of heat transfer. | ||
| Smadd |
Blake. Not meaning to start another oil thread...  But are you using Mobil-1 15-50 automotive? I think I'm switching to that as it's readily available in my neck of the woods. Seems to me you said it was good stuff. (Don't wanta get too technical!) Steve | ||
| Blake |
That and/or the 20W50 V-Twin stuff. Depends on whether I'm at Walmart or the dealership when I need oil. | ||
| Aesquire |
A good computer store or electronics shop can get you heat conductive glue. It's used to bond heatsinks to motherboard & video chips. Contact must be very flat to get good heat conduction and a minimum of glue. Lapped chips etc are common with the overclocker crowd. ( computer hot rodders ) That said, Blake is right, You want to get the oil hot enough to evaporate the water. My mom used to commute 3 blocks every day, and rusted out exhaust systems at a phenomenal rate because the pipes never got hot enough to boil off the acid laden water vapor that condenses in the pipes (and oil). You REALLY want to run a thermostat on an oil cooler. | ||
| Hootowl |
re. boundry layer at cylinder wall, isn't it this layer that protects the wall from excess heat? When detonation occurs, this layer gets blown away, and damage occurs. Am I confused? | ||
| Djkaplan |
"You totally ignored the crux of my point." Blake, I am not ignoring your point; I am disagreeing with it. If oil could be effectively cooled by a simple sump with fins on it compared to a relatively complex and expensive oil-cooler, then that's what the supplementary, thermostatically controlled oil-coolers would look like if they were added to an oiling system. I'm still looking up the information to support my statements. I haven't looked at my heat transfer and fluid dynamics books in over 20 years; it's taking a while to digest (again). Hope I still have the article by Kevin Cameron where he touches on these very points. As if I didn't have enough to do with my free time! Good stuff, this. Will be back. | ||
| Rick_A |
99X1...Motorcycle specific motor oils are generally designed for use in motors, trannys and wet clutches...they indeed do have different additive packages than automotive oils which are designed for engine efficiency and protection only. | ||
| Sarodude |
DJ & Blake- Maybe the disagreement from you guys comes from a misunderstanding... I THINK DJ claims that a low surface / volume (surface is wrt OIL contact) device won't cool oil as effectively as a properly designed device like an oil cooler. This is aside from the boudary layer stuff... I THINK what Blake is saying is that something is better than nothing... An aluminum oil tank is better (at cooling) than a steel one. Words like "good", "bad", and "effective" are dangerous. Loli has been trying to get me to "take it easy" during my workouts. I have been - by my definition. Apparently not by hers. I don't know if she can cite an Exercise Physilogy text that quantifies "Take It Easy" as some magic formula combining caloric burn, heart rate, and hat size. She thinks I've been ignoring her. I've just been taking it easy as I know how. -Saro | ||
| José_Quiñones |
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| Blake |
DJ, "If oil could be effectively cooled by a simple sump with fins on it compared to a relatively complex and expensive oil-cooler, then that's what the supplementary, thermostatically controlled oil-coolers would look like if they were added to an oiling system." Why would you use a large, ~3 quart, capacity heat exchanger when all you need is a 4 once one? That makes absolutely NO sense to me. An oil cooler is the optimum form of an inline, controllable heat exchanger. A 3 quart finned aluminum tank is not. Can you see why? What I'm saying is that a 3 quart aluminum oil reservoir with fins that are exposed to ambient airflow could shed comparable amounts of heat as a little 4 once oil cooler. JQ is trying to show us the exposed bottom surface of the crankcase/sump of the V-Rod. It appears to have integrally cast stiffening ribs that would also act to enhance engine cooling. But mainly they are for added strength to protect against possible impact damage. Way to go JQ. You may need a new title... Chief BadWeB Photo Journalist. | ||
| Bomber |
Blake . . . . I've had an ephiphany! Thanks . . . . after years of tryin to be able to explain what I had deduced at some subconscious level, I GET IT! thanks ps, have you considered going into teaching, and getting paid for what you do for free here on the web> | ||
| Sparky |
I just switched engine oil to Harley's Syn3 20-50 in the Firebolt at the 10k mile service. After driving it around town for the first 30 miles or so all seemed normal as compared to when it had the non-synth oil, but the first time I made a high speed pass, I was astounded at how quickly it went from 80 to 110 mph. I don't recall it accelerating this fast from 80 before. I realize this is just a seat of pants impression and maybe I am wanting to believe it is faster, so I'm wondering if there is something in this oil that would make a difference in performance and would this show up on the dyno? Sparky | ||
| Blake |
Bomber, Yes. Send money!  | ||
| Blake |
Ara, We used to use a silver filled epoxy to repair the passive RF (radio frequency) surfaces of earth station satellite antennas. It is conductive electrically and so should also work well thermally. Try... a Google Search for... conductive silver epoxy. Lots of hits. | ||
| Bomber |
Blake I'll buy you a beer this August . . . beer is coin of the realm, yes? I remember seeing an BMW in the late 70's (R90s, mebbe?) tricked out with every accessory know to upright mankind . . . one of them was an oil pan that had tubes running through it fore and aft, to allow the passage of air "through" the pan . . . more effective than nothing at speed, I guess (although Ihave no idea what happens to the airflow just aft of the front wheel that clse to the ground), although pretty useless at parade speeds and redlights . .. when I asked what he did duyring cold weather ops, the rider showed my a pocketful of appropriately sized corks . . .. odd, those bimmer riders | ||
| Blake |
I know of a few holes I'd like to see corked. ![:]](http://www.badweatherbikers.com/buell/clipart/proud.gif) | ||
| Bomber |
ba-dum-bum . . .. (chuckle) | ||
| Reepicheep |
Just a note to everyone using the big Ford filter (FL1A?) on their Buells. Do safety wire it. Otherwise, you might be blowing down your favorite set of twisties (Ahem... River Road), notice a big cloud of white smoke behind you, suddenly notice you have zero back brake, and wonder why the back end feels so squirelly. You would then have to pull over (Ahem... Procter and Gamble Research Facility parking lot) only to find your entire motorcycle from the front head back and down SOAKED with oil, including your right pants leg. Fortunately, you would probably still have a quart of oil in the tank, enough to get you to the nearest auto parts dealer (Ahem... Napa) and add more oil (Ahem... Valvoline 20w50 synthetic at $4.79 a quart). Another $2 for the nearest car wash (apply soapy water liberally to both bike and pants leg), and you are again good to go. So add a big hose clamp and a tie down to those big filters. I've heard stuff like this could happen. Bill "Huh? who me?" Kilgallon | ||
| Djkaplan |
Blake, Sorry about the late response. Current events kind of got me away from our discussion about the validity of using fins on an oil tank for effective cooling. I come with references to support my earlier statements and will use them to counter specific statements posted by you - all in good fun, of course. My clumsy explanation of an "insulating boundary layer" was the result of dredging up information logged away 20 years ago with an imperfect information system (my memory). The layer I speak of is the layer of fluid that actually contacts the inside surface of any container that holds it. **Since the velocity of the fluid layer adjacent to [a] wall is zero, the heat transfer between the surface and [the] fluid layer must be by conduction alone.** pg. 197, Analysis of Convection Heat Transfer Basic Heat Transfer Krieth and Black Harper & Row This layer of fluid that exist in any container that holds oil can never be turbulent if the velocity is zero. This is what I meant by an "insulating layer", the conduction at the interface (more on this later). But this is ultimately not the only reason why a sump with fins can not be as efficient as a small oil-cooler. The explanation is more complex than my simplistic earlier responses implied. I'd like to get straight to the point and counter a specific statement you posted. This statement pretty much sums up the information I disagreed with in earlier posts. "Suppose the oil cooler's cooling passages have a capacity of 4 onces (1/8th quart) an internal surface area of 20 square inches and an effective external surface area of 40 square inches. If we assume that we have a 3 quart total oil capacity for the engine/reservoir/filter, the oil cooler represents 1/24th of the total oil system capacity. The equivalent surface area corresponding to the total capacity would be 480 square inches (24 times 20 sq inches). Comparitively, the oil tank would hold roughly 2.5 quarts (5/6 of the total oil system capacity) with an interior and exterior surace area roughly equivalent at around 300 square inches (guesstimate) for an equivalent total capacity surface area of 360 square inches (6/5*300). That's not too far off from the total capacity equivalent volume of the oil cooler. In other words, with the addition of some fins and vigorous airflow, the cooling potential of an aluminum oil tank could be comparable to that of an oil cooler." This can not be true. You are only taking into account surface area for a sump vs. oil cooler and disregarding two important considerations: a) fluid velocity b) the ratio of inside surface area/fluid volume FLUID VELOCITY In forced convection, fluid velocity has a direct bearing on heat transfer. **The temperature gradient at the wall depends on the flow field, with higher velocities being able to produce larger temperature gradients and higher rates of heat transfer. pg. 197, Analysis of Convection Heat Transfer Basic Heat Transfer Krieth and Black Harper & Row The flow in the small passages of an oil-cooler are much higher than the flow of oil circulating through an oil storage tank. The rate of heat transfer (even if surface areas are equal) is much higher in an oil-cooler based on just this one premise. Remember, we're talking about velocity here and not volume. RATIO of INSIDE SURFACE AREA/FLUID VOLUME Oil-coolers have large area to volume ratios simply because of their construction. A long, thin, flat box is going to have more surface area than a short, fat, deep one if they surround the same volume. If heat transfer along a surface is conductive, more efficient heat transfer takes place when you have a relatively small amount of hot fluid moving past a given surface area than a large amount of hot fluid moving past the same surface area. I didn't say more heat transfer, I said more efficient heat transfer. The conduction taking place at the interface between the fluid and the inside surface of the container places a limit on the heat that can be transferred from a large volume of oil regardless of the surface area on the outside, hence, my feeble attempt to describe an "insulating layer". I should have said "bounding layer" of insulating oil. There are examples using free convection that are simple sumps of oil with cooling fins though; we see them every day on top of poles that carry electrical equipment. These are applications where long term maintenance is troublesome and not financially viable. Of course, the answers are even more complicated than my simplistic attempts to explain can convey, but I still stand by my arguments. I disagree that, "a 3 quart aluminum oil reservoir with fins that are exposed to ambient airflow could shed comparable amounts of heat as a little 4 once oil cooler". Please realize I never said you were wrong; fins on a sump will offer some benefit, just not nearly as much as you would think. I am awaiting your response. Whether I like it or not, I (re)learn something every time I reply. |
