| Author | Message | ||
     Towjam |
What determines if a bike (such as as the XB) is considered oil cooled or air cooled? or to ask it another way, why are Sportsters considered air cooled but XBs considered oil cooled? (Unless someone has changed the "rules", putting an oil cooler on a Sporty - or any other Harley doesn't make it an oil cooled bike.) | ||
| Cycleaddict |
air draws the majority of the heat out of the motor. IMO buells are air cooled with a oil cooler! | ||
| Towjam |
air draws the majority of the heat out of the motor. IMO buells are air cooled with a oil cooler! Agreed. On the other hand, you have bikes like the BMW boxers which actually have separate oil lines for cooling and for lubrication. In those cases, I can see how they can be classified as "oil cooled". Seems to me that Buell may be stretching just a bit to consider the XB oil cooled. (Not that it really matters, I love my XB - I was just curious...) | ||
| Cycleaddict |
i own an "oilhead" BMW and it has two oil pumps one for lubricating the motor & the other to pump oil to the exhaust valve seat area and the oil cooler. hence the name "oilhead" | ||
| Strato9r |
I'm not exactly sure where the line is drawn where oil becomes an actual coolant medium over and above what it accomplishes while merely lubricating the engine. Oil is not a really great coolant, but, it can be very effective at reducing the operating temperature of critical engine components. Piston cooling jets, as used on a variety of engines, allow significantly higher boost pressures, higher compression ratios, and higher nitrous loads, by cooling the underside of the piston enough to allow the heat built up on the crown of the piston an alternative radiant path, lessening the demand on the ring land areas, which see an enormous amount of heat. In this case, the oil is indeed a coolant. I would imagine that the same effect could be had if oil was ducted passed any area of the engine that heat were prone to build up in; between the exhaust seats of a 4 valve engine, around spark plugs, that sort of thing. From what I gather, XB's have piston cooling jets, maybe that's why they are "Air / Oil" cooled. Let's ask an expert, though. OK, Beemerfolken, what exactly makes an Oilhead an Oilhead? | ||
| Strato9r |
Thanx, Cliff, you answered my question! | ||
| Jaimec |
Actually, doesn't Buell list the XB as being "Air/Oil/Fan cooled?" | ||
| Rocketman |
The GSXR 750 was the first bike of the modern era to employ the use of oil squirters under the pistons. Since this time, circa 1985, the expression 'oil cooled' when referring to motorcycles has meant exactly that. Oil squirters are present under the pistons. The fact many are unaware of such some 20 years later just shows the importance a company like Buell would place on such claims. 'Hey look, we joined the modern era incorporating such technical advancements of oil cooling on our motorcycles'. See how the marketing hype works? It's exactly the same bullshit as all the fancy abbreviated names we are constantly bombarded with by the auto industry. Rocket | ||
| Towjam |
Actually, doesn't Buell list the XB as being "Air/Oil/Fan cooled?" I'm thinking that the fan is necessary due to the rear cylinder's lack of exposure to open air. If this is true, the fan is more of a band-aid than a feature. Still, I prefer it to a water cooled engine. | ||
| Fdl3 |
I'm thinking that the fan is necessary due to the rear cylinder's lack of exposure to open air. If this is true, the fan is more of a band-aid than a feature. Still, I prefer it to a water cooled engine. "Band-aid" is an interesting term to use regarding the rear cylinder fan.  It seems to me the function of that fan is well documented. It's presence is planned and appreciated, not a hap-hazzard "fix". I guess I am not seeing how you understand the concept of the rear cylinder not getting as much air flow as the front cylinder, and yet say the fan is a "band-aid"? | ||
| Altima02 |
Maybe because the fan uses AIR to cool the engine. You don't call your car "water-pump cooled"  | ||
| Towjam |
"Band-aid" is an interesting term to use regarding the rear cylinder fan. It seems to me the function of that fan is well documented. It's presence is planned and appreciated, not a hap-hazzard "fix". I guess I am not seeing how you understand the concept of the rear cylinder not getting as much air flow as the front cylinder, and yet say the fan is a "band-aid"? I didn't say the fan was a "hap-hazzard fix". On the contrary, I think it's a very suitable workaround that's preferable to a full blown water-cooled engine. There's no way you could stick that rear cylinder back behind the twin spars and expect it to get the adequate air cooling without the fan. I may have come across a little harsh in referring to it as a band-aid but it's definitely a workaround. | ||
| Tim |
What determines if a bike (such as as the XB) is considered oil cooled or air cooled? Marketing. | ||
| Teddagreek |
IMO the oil cooler is supplemental VW motors are Air cooled but there is a Oil Cooler under the fan shroud.. | ||
| Ft_bstrd |
Name a single air-cooled engine where the cylinders are NOT in the direct flow of air flow that does NOT have a fan. I can't think of one. | ||
| Jaimec |
Ummmm... you're not thinking hard enough... Every single "modern" pushrod Harley Davidson made? Not only is the rear cylinder blocked by the front cylinder, but the hottest part of the rear cylinder (the exhaust port) is even further out of the cooling airflow. Of course, since Harleys aren't tuned as highly as Buells that under MOST circumstances it isn't a problem (but then again, read the boards around the time the TwinCam 96 engines came out to see what kinds of cooling problems Harley had with them). Even before the TC96, my friends with Evos often had to shut their bikes down and pull over to the side of the road in summer bumper-to-bumper traffic here in New York. If they didn't, the pinging became intolerable (not to mention what was happening inside the engine to produce all that detonation). Face it, that Sportster-derived engine is really a POOR design for a high performance engine requiring all kinds of workarounds to get around its inherent design. For a lot of readers here, though, loud annoying fans and weird, asymmetric air scoops seem to be preferred over simple, proven water cooling. Go figure. But there really isn't that much of a need to jump both feet into water cooling either! Increase the number and depth of the cooling fins on the heads, increase the size of the oil cooler and work on improving airflow through it. Open up the oil passages more and go hardcore oil cooling. Why not? The GSXR eventually had to go water cooled due to the amount of hp-per-liter it was producing, but the Buell engine is nowhere near that level yet so shouldn't need that level of cooling. $.02 | ||
| Old_man |
They're all air cooled, even the bikes with radiators. The water is just an intermediate step to the air cooling it. | ||
| Skully |
For a lot of readers here, though, loud annoying fans and weird, asymmetric air scoops seem to be preferred over simple, proven water cooling. Go figure. Is having water pump, water and glycol coolant, fans, hoses, and an ugly radiator really more simple? I've had radiators and water pumps fail leaving me stranded. Plus the added maintenance of having to change hoses and coolant periodically. I ride my XB in traffic and race here in Texas in July. I've never once had it overheat (go into skip-spark mode). I love the simplicity of this motor and am willing to live with less power/cubic inch. When I purchased my Buell, I had just sold a Softail. I had enough $$ to cover a brand new Ducati 999. The simplicity of the XB won and I've never regretted the decision.  | ||
| Towjam |
The fact that it isn't water cooled is one of the reasons I like Buells. I'll choose the fan and other workarounds of an air/oil cooled engine over the added complexity, weight and maintenance of a water cooled bike. | ||
| Ridrx |
Alright, my HD knowledge is non-existent. I have wondered for a while now why the cooling fins are perpindicular to the cyl. centerline and not parallel to the air flow. I'm far from an engineer, but it seems like you could increase the volume/speed of the air over the cyl. by having the fins in a horizontal arrangement. Is this one of those "design features" that's used only to accentuate the 45 angle of the HD twin? OR do they promote more even cooling in the current configuration? | ||
| Ft_bstrd |
Ummmm... you're not thinking hard enough... Every single "modern" pushrod Harley Davidson made? Not only is the rear cylinder blocked by the front cylinder, but the hottest part of the rear cylinder (the exhaust port) is even further out of the cooling airflow. They ARE in direct airflow. Although the air to the rear cylinder is decreased compared to the direct airflow of the front cylinder, it is in the airflow. The frame is also much less restrictive to airflow. Buell has the problem of having the rear cylinder nearly completely covered by the frame, seat, transmission, and intake track. The airflow is simply insufficient to provide adequate cooling. Ergo, the fan is a simple way to increase airflow. The same solution is used by VW, Porsche, Corvair, Citroen, etc where direct airflow is insufficient. It isn't a band-aid fix but rather a solution that is tested and dependable. | ||
| Blake |
Skully nailed it.  The cooling fan along with the rest of the Buell XB computer-controlled, ducted, multi-speed, forced-air cooling system is an extremely solid solution to a complex ages old engineering problem. A radiator with thermostat, glycol, water pump, and all the complex plumbing and water jacketing of a liquid cooling system address the same exact problem, preventing overheating and maintaining engine temperatures within a desired range of consistency. Referring to the fan as a "band-aid" implies to me that the author sees the fan as a cheap fix meant to cover up a problem. It is a heck of a lot more than that. Some day maybe it will even be quite. | ||
| Reepicheep |
Funny this should come up. I had to put an extra half gallon of coolant into my Saturn just to be able to get to work this morning. It was 35 degrees and raining, otherwise I would have taken my more reliable air cooled Buell Looks like I will be spending time during the next few days diagnosing a weepy Saturn cooling system. |
