So which is it, John?
Well this month, I’m going out on a limb. I plan to use a littlepersonal common sense and let you know how I feel about oil-coolers.Here’s the official disclaimer: this is my opinion, and not theopinion of Mr. Ball, Sin Wu or anyone else. You are welcome to sharein my ramblings, think I’m a genius, recommend me for a gold star, orfeel free to shower me with praise next time you see me. At the sametime, you are more than welcome to disagree with me, tell all yourfriends what an idiot I am, or scorn me for ever more. Differentopinions make this an amazing country to live in, right or wrong.
Get to the point, John.
During the hot summer months, riders seek to insure that theirbikes don’t overheat. If you own an American bike, and its not aV-Rod, you’ve got an air-cooled motor. Most of our metric bikefriends, and the V-Rod riders, have water-cooled engines. As basicas this sounds, either water and air, or oil and air cools yourbike’s engine. Why? I’ll tell ya. Because you are being propelleddown the road by an internal combustion engine. Combustion (theexplosion) of your fuel (gasoline) moves the pistons in your motor,which generates heat. On top of that, the movement, in closeproximity, of the internal components of your motor (rods, pistons,gears and the like) create friction, which generates additional heat.If you don’t control the heat associated with these mechanicalfunctions, all this metal stuff in your motor will melt together likecandle wax and you’ll end up on the side of the road. Not good.
Yeah, yeah, get to the goddamn point, John.
If you’re reading closely, the common cooling feature found ineither water-cooled or air-cooled engines is AIR. Air is the commondenominator that cools your motor, whether you have just oil runningthrough it, or oil and circulating water (anti-freeze coolant)flowing though pockets inside your crankcase. The ultimate goal isto dissipate the heat generated in your motor into the atmosphere.
Yippee, get to the point, will ya.
If you’ve got a water-cooled engine, you’ll be sporting a radiatorsomewhere on your machine. Normally it’s a rather ugly piece of gearaptly named because it radiates the heat captured in the water that’scirculating through your motor. A typical radiator is composed ofthin circuits of compressed tubing through which the water or”coolant” flows. Air passes by the radiator fins, and the heatenergy is dissipated into the atmosphere, so the coolant can onceagain flow into the motor to cool the hot cylinders. If your vehicleis sitting still and no air is flowing through your radiator, heatwill build up and you’ll overheat your motor. To alleviate thiscondition, vehicle manufacturers place electric fans in front ofradiators to assist the flow of air. Flowing air is the mostimportant component to transfer the heat.
This is all about cooling an American V-Twin, John.
Your American V-Twin is a time-honored, incredibly good-lookingdesign, which incorporates an air-cooled motor. Confused yet? Yes,air does cool your motor, but it’s also the oil in your motor that iscirculating and dissipating the heat being generated. Most V-Twinshave only a 3-quart capacity of oil that circulates in and out of themotor. If you’re a quart low on oil, you’ve reduced your coolingcapacity by about 30%. That’s why it is very important not to runyour bike low on motor-oil–even more so when it’s hot outside. Theoil is also flowing at a relatively low pressure in your motor. Theoil pump, depending on the oil temperature, generates only 5 to 15pounds of oil pressure. If you’re oil is extremely hot, you’ll looseoil pressure and that results in engine damage. Sounds like you needan oil cooler, right? Well, not so fast. I’m still trying to get tomy point here, bear with me.
Oil lubes the engine. It doesn’t cool the engine, John. Ifit did, the oil would be stored in a radiator-type contraption. Whatare you trying to say, John.
Air is the key to cooling your V-Twin. That’s why your motor haslarge fins all around the cylinders, which add more surface area forwind to cool. This additional surface area that you see on yourHarley type motor works just like a radiator on the water-cooledmotor. Air passes over the fins when you’re moving, and that coolsyour engine and it’s components, including the oil circulating fromyour oil tank into your motor. If you’ve got an oil cooler it willadd an additional “radiator” type unit, to your oil circulationsystem, to dissipate the heat stored in the oil.
Yeah? As far as I’m concerned that’s cool.
As much as you’d like to run out and buy an oil-cooler, I’d adviseyou to keep your wallet in your pocket. Now, I’m finally gettingaround to my Covington Code regarding why I think you should skipputting an oil-cooler on your bike (see disclaimer above). An oilcooler only works if you’ve got air blowing through it. When you’removing, an air-cooled V-twin motor cools just fine, because you’vegot air blowing through it. The same principal applies to youraccessory oil-cooler; it needs air to circulate through its radiatorto cool your motor. The problem is that I’ve yet to see an oilcooler designed for a V-Twin that includes an auxiliary fan, like awater-cooled radiator.
Ah, your notion is beginning to slip, John. More fins from acooler add surface area to the cooling process while the bike ismoving. The only reason we have internal combustions engines is to”move”. If you must stop, hopefully the oil and engine has cooledenough to survive the pause.
About the only time your bike is going to overheat is when you’resitting still, low on oil, or you’re pondering another route toavoid the traffic jam you’re stuck in. If you’ve got an oil-cooleron your bike, sitting still with your motor running, you’ll bereducing the oil pressure by forcing the oil through the cooler. Thewhiz-bang oil cooler won’t be cooling your oil because it has no aircirculating through it, so you’re in double “heat” jeopardy. Plusyou’ve added about four more oil hose fitting locations creating moreplaces for oil to leak from your bike. If you’re leaking oil, you’reloosing the cooling property and contents of your oil-bag andreducing the ability of your air-cooled motor to cool properly. Note:Harleys don’t leak; they just mark their spot.
One of the reasons I run coolers is to enhance my motor oilcapacity, goddamnit.
Last but not least, I can hear you “Oil-Cooler Advocates” yellingright now that it’s 120 degrees out here in the desert, and you needall the help you can get. Bah-humbug. Your V-Twin is well designedto run at around 215 degrees of oil temperature. If the ambient airtemperature is 90 or 120, your motor really could care less as longas it has air blowing through it, regardless of the air temperature.I’d rather have more oil pressure lubricating my internal combustionengine to keep me going, than a $150 oil-leaking accessory bolted tomy bike that’s not helping me cool my motor.
Okay John, but what about the Twin Cam engines that run 240degrees plus? I installed a H-D cooler and tested it on the run toBarstow. It generally ran 20-25 degrees cooler. Is that bad? Plus thecooler and lines added to my 4-quart capacity.
In summary, I think the best thing you can do in the DesertSouthwest is change your motor oil often, make sure your oil level istopped off, and avoid traffic jams. I also run 25/60-weight oil inthe summer, vs. the standard 20/50-weight oil normally used in yourlate model bike to add an extra margin of heat protection that thehigher viscosity oil will provide. I say keep your money in yourpocket next time somebody tries to sell you an oil-cooler. Spendyour cash on a date for those hot nights Give her a ride to the showon your bike, have a good time, the air-conditioning in the theateris amazing this time of year. That’s way cool.
Here’s a couple more thoughts to consider. The guys at thefactory told me that H-D oil is rated to 360 degrees. During our testmy brother’s Evo dresser ran an easy 90 degrees less than the TwinCam King. What does that mean? Evos are already cool? I’d rather runa cooler and be safe.
One more thought. Evos run substantially cooler, but withconsiderably less capacity. My Dyna only held about 2.5 quarts. Ifoil volume is a consideration and you’re running 2.5, you could addto that number with a cooler.–Bandit
Keep the rubber side down,
John Covington
www.musclebikes.com
Back to the Surgical Steeds…
