I decided to try out a non-white background as some viewers say it's hard on the eyes in the dark. So what do you think, this background or the usual white?
When I was trained as an aircraft engine fitter, one of the first questions we were asked was 'what does the oil do?' and we were told that apart from lubrication it was used to cool the engine. With some large air-cooled aircraft engines the oil tank itself was 24 gallons or so and even though these engines used a lot of oil, the oil was cooled by an oil cooler and also by air flow around the tank. Notably gas turbine engines do run hotter in the turbine area but do not use the oil to cool the parts very much. The oil is often used to heat the incoming fuel as kerosene is not good at very low temperatures. However these turbine engines have very small oil tanks, normally only a gallon or two. As they don't use much oil, this is fine. Oil in modern turbocharged engines is also used to cool the turbine and compressor bearings but many of them also use water cooling of the turbocharger. These are especially useful on shut down where the oil can boil in the bearings and cause damage. But you are correct in saying that eventually the engine and its parts are cooled by ambient air.
There is a point in which oil is no longer sufficient for cooking either. After that the most common method is liquid cooling with the fuel. This is jet and rocket territory now but most turbines have a cycle to bring fuel through the engine to cool the turbine as well. Mainly again, in very very powerful turbopump engines and the like. Well past oil at that power level.
in gas turbine engines the oil is pretty much only to remove heat from the bearings, it's all ball and roller bearings so there is no sliding friction. The oil is also very thin
aircraft air cooled engines are someting special because air cooling is not the best choice: at climb at full power is the cooling too low because low speed, at level flight is the cooling perfect but the badest moment is the descend before landing: oil is very hot, the engine is reduced to idle, then the cooling is much to high= the pistons are grow from the oil heat and cylinders shrink due to the airflow and the low heat in the combustion chamber= high risks to size the engine.To avoid this, are air cooled engines made with very large gaps between piston and cyclinder, this increase the overall oil consumption and increase the blow back in cold condition (and make the engine difficult to start in cold condition). A liquid cooled engine avoid such problems because a much better t° regulation, this explain why air cooled engines tend to disapear because they emissions are much higher on such engines because oil consumption+ run rich to avoid knoking...
In the 80's. There were two 911SCRS rally cars in the middle east. One was a factory car, the other a prodrive. The fatory 911 used to overheat in the Gulf rallies. Prodrive simply installed a huge oil cooler, problem was solved.Car won the championship for multiple years.
well the more hotter the oil is it give less protection and lubrication that make more heat and create heat loop. Breaking the oil film loosing compression and power.
I've always wondered about super cooling an engine. I know it's not cost effective but if you could use liquid nitrogen cooling for the exhaust and cylinder head combustion chamber. And for that matter if you could use it on intercoolers for turbos and blowers where it ran through the equivalent of a intercooler that fits in a area below the throttle body so the intake air is cooled to close to 0°C before the fuel is injected.
@@theEVILone0130Think about the drawbacks. If you carry Nitrogen as a coolant, it would have to have a compressor and a complex system to get low-pressure and high pressure zones to obtain said cooling and recycle the nitrogen. And if you just release the Nitrogen, you'd have to carry a heavy tank to store it, and be recharging the Nitrogen constantly. Sounds like a cool concept though.
Some nuclear reactors used by soviet submarines went as far as to use molten metal as the fluid for their cooling system for the sake of compactness. This meant that they could under no circumstance stop the reactor during the submarines' lifespan or else it would solidify.
I like the relative simplicity of an oil cooled engine like the one in my 2001 Bandit, the fact that leaking gaskets will never result in water contaminating the engine oil, and that there are no water pumps or coolant hoses to corrode or fail. An ideal engine for me would be an oil cooled, fuel injected triple with a thermostat and a fan.
An oil cooled engine requires a higher volume oil pump and the increased temperature change of the oil leads to faster degradation. Almost all oil cooled engines have a thermostat. Ideally for power you need to go the liquid cooling path or if reliability is your thing then air it is. Oil is something in between.
@@soldrier Degradation only for the oil. I'm running a suzuki oil burner on 15 psi of boost putting down 250 wheel - 250% of stock power. Oil lasts the same, and the only cooling mod is a larger 19 row racing transmission cooler repirposed to replace the stock one. I had the opposite problem where in fall the bike struggled to keep operating temp from the larger cooler. AFAIK no SACS motors used thermostats, not the 1157s 1127s 750s ect. EXTREMELY reliable, you can be pissing oil and aslong as it's topped off there's no issues. It's also better to not have to worry about deck types and headgasket issues without the waterjackets, never underestimate an old oilboiler.
@@remedia1200 Yes indeed, only oil degradation failed to mention that. Now I don't know what engine we are talking about. I'm only aware of late 80s early 90s sport bikes being oil cooled. I mean in an essence all engines are oil cooled even the 2cv had a radiator. You're right about that it's harder to reach operating temps :).. Now from an engineering standpoint. Having more oil to cool the engine only leads to slower warmup time influencing emissions. Wear in modern engines is not so of a problems as UA-cam mechanics would lead you to be. Also heat in an ICE is highly localised. Yes you can use your bike at 250% power but for how long? Those new castings, open block designs etc. While bad for reliability, are an excellent solution to keep heat down on high powered engines. No wonder nothing else caught on. :)
@@soldrier you'd be surprised - i'm running low number compared to some. There are 400 -500 hp bikes ou there that have been running quarters for years. Good top fueling/cooling with watermeth, rich mixture, intercooler and oil cooler makes them very happy under boost.
As usual your videos are great. I'm a mechanical engineer but since I'm from Italy this videos helps me to learn A LOT of technical words about engineering. Your videos are clear even for a beginner like me 🤣 Thanks for sharing your time with us and create these masterpieces!
I remember talking to a Porsche 911 930 owner. He told me, that the engine is oil-cooled, not air-cooled, because there is 14 liters of oil in the system. When normally in water-cooled 6 cylinder engines it's 6-8 and maybe sometimes up to 10 liters of oil.
I like the comment ‘it’s blurry’ between Air/Oil cooled. I don’t think it has anything to do with there being an oil cooler. The Porsche 911 is both oil cooled and air cooled.
Those 3l Porsche engines are air-cooled. Compare a 6l small block uses ça 5l of oil, 6l if it got an oil cooler, 7l of oil if external filter and external oil cooler are present. 9l if you add a vaccum reservoir for the oil. I build my street racing small blocks with 7l capacity and a very flat oil pan and increased the water circuit by 4l with an external tank riding in the airstream. It's essentially a dry sump and heat radiation from the pan is lower. A finned sump cover could help but in my climate this was not needed. My cars run cool on a 35 Celsius day. 14l oil capacity on a Porsche means that the engine has some serious engineering defects. That's why I stayed away from racing Porsche and my motors and cars are simply better than what Porsche does. 500hp at 5600 and 900kg is fun. A 1800kg Porsche with 400hp/7000 is boring.
I’m a BIG fan of your channel. Your automotive presentations are the best balance of accuracy and accessibility on the web. Having said that, I was surprised to see what I consider a bit of a stumble in this video (engine cooling). Please tell me if you agree with these criticisms of this episode: Combustion, not friction, is the major source of engine heat. Lubrication, not cooling, is the major defense against friction. The function of engine cooling is to remove combustion heat from the engine. Properly lubricated piston rings don’t create engine-damaging heat, rather, they transfer combustion heat to the cylinder walls which are cooled by air or liquid. So, I think your focus on friction in relation to cooling is misplaced and potentially confusing to the uninitiated. No amount of cooling will save a poorly-lubricated engine. Please keep up the good work producing informative, no nonsense automotive videos!
8:57 Classic British bikes used a similar dual oil pump, but the high volume side was to scavenge oil from the sump to the oil tank. In my 1966 Norton 650SS high pressure oil is directed at the underside of the piston crowns to provide cooling, with the heat being dissipated to some extent by the oil tank.
I really wasn't expecting this video to be that dense of information and everything to be explained so well. Really good content keep up the good work!
I've been a subscriber for a while now. Your videos lately have been top notch! This channel will continue growing fast if you just keep up the good work.
I already knew this stuff, saw the video in my recommended and decided to watch out of curiosity and im positively suprised. Everything is explained simply and clearly. so much info for a 14 minute youtube video, it would take me likely something closer to and hour to actually explain all this stuff to someone who doesnt know it. thumbs up.
5 more advantages of AC motorcycle bikes, not mentioned in the comments (yet) are: 1) The weight difference - a liquid cooled motorcycle will weigh more. 2) An engine being a complex mechanical machine. You can both hear and listen to the motor more acutely. A water jacket in an engine is a sound insulator. Some would say this is a good thing as liquid cooled engines are quieter than air cooled engines, I just disagree. 3) In air cooling systems, the engine is not subjected to freezing issues (I know, I know... liquid coolant, has anti-freeze properties). 4) No danger of coolant leakage or low level in air cooling system. 5) An air-cooled engine can take up some degree of damage. A broken fin does not affect much while a hole in the radiator may stop a water-cooled engine. Yeah, OK... I'm old school.
less appreciated these days is the difference in consequences of overheating an air cooled engine vs a water cooled one. If a water pumper ever over heats bad enough the block and heads are usually toast... you are usually "done" driving until the engine is fixed or replaced.With an aircooled engine, all that is required is to get over to the side of the road, let it cool down and you are on your way again.
@@caty863 Its an advantage if you like the sound its making, and is a disadvantage if not. Its for the same reason people put louder than stock mufflers on or, why the stereo has volume control and a off button.
I had a Suzuki that go around the problem with uneven cooling on the rear of the engine on an air cooled engine in an interesting way - the front cylinder was air cooled, but the rear cylinder was air/oil cooled. I have a DR650 now, and it has a weirdly large oil cooler for a 650cc engine. But that thing just won't overheat. I'm really digging the new background. I'd love to see more of this.
Always something of value to learn from your excellent presentations. I catch very few misstatements very occasionally and mostly pick up some facts or perspectives. Thanks. You start this presentation with a curious attribution of friction as the primary cause of excess heat. The rest of your presentation shows you know that combustion produces the lion's share of excess heat--the sixty to seventy percent inefficiency of the cycle. Friction's contribution is miniscule compared with that of combustion. In 1971, in a first-year thermodynamics class toward my mechanical engineering major, the professor asked this very question, that is, where does an internal combustion engine's excess heat come from. One of us students immediately answered, "friction." I vividly remember the professor's astonishment at our ignorance. He said something to the effect that if friction were producing anywhere near (within two orders of magnitude) the heat of combustion, the metals subject to such friction would quickly melt, bearing in mind that the local interface of frictional heat generation is instantaneously very small. Remember, too, that gas flow and introduction of evaporative fuel (as you detail) carries off most of the excess heat of inefficiency. Still, as you show, engine cooling is concentrated around the combustion chambers and exhaust ports. Along these lines, Rotax 900 series aviation engines utilize a hybrid cooling system; liquid cooled heads and finned, dry cylinder barrels sufficient to remove the residual heat of combustion carried into the cylinder walls (and, ok, that little bit of ring/wall frictional heat).
Your comment is to the point, it was really a bizzare intro stating that friction is key heat generator in the internal combustiin engine. Total loss of credibility
What most people do not realise is that the oil not only lubricates the engine, it is also a very important coolant within the engine, whether air or water cooled...
Friction is minor heat source, these are combustion engines and that is the main source of heat. Air compressors get hot because of the compression, but the combustion engine compresses and then decompresses the air if there is no fuel and spark added, so the net Heat would be insignificant because the heat would transfer to the air it's self and therefore be exhausted. the movement of air would be cooling. But, when you add Fuel and Then combust the mix by spark, the actual heat coming from this combustion is what runs the engine and an unavoidable consequence is heat. That is the main reason why most ultra efficient engines today have a energy to work conversion of less then 50%, that means that the other 50% is heat and other forms of energy that do not translate to work, or in other words locomotion.
This man somehow makes my ADHD brain keep focused for more than 2 minutes on a complex engineering topic, puts it in a way I actually understand (I'm quite stupid) and makes it enjoyable in the process.
Most of the heat in the engine is from the combustion... Compressors that is basically the same as an engine but without the combustion do not get nearly as hot as a similar sized engine.
Friction is only a miniscule percentage of the heat rejection of an internal combustion engine. This kind of ignorance of basic thermodynamics drives me crazy.
Interesting and easy to understand video like always. I have owned several motorcycles and scooters since I was young. Some of them were air cooled, other water cooled... but I loved them all! I would like to share two ideas: some scooters have a special type of cooling system, "forced air cooling system". The forced air is provided by a small fan moved by the engine. The old Vespino had that interesting system. And many current scooters use that technology. The Spanish engineeres of the humble Vespino were very creative and invented the continously variable transmission. That mechanism is nowadays very common in the scooters and even cars. Nobody knows that this transmission method was created for this low displacement vehicle.
Fantastic video. The other disadvantage of air cooling (and advantage of water cooling) is increased engine noise as the cylinders aren't surrounded by a water jacket which acts to muffle combustion noise.
Great video, I didn`t know that there were engines actually circulating oil around the combustion chambers. I would add that the biggest advantage water has over oil as a cooling fluid is it`s thermal conductivity. Combined with the thermal capacity it makes water about 8 or so times better as a cooling medium. Keep up the great content, I am learning tons from each of your videos.
I enjoy your videos and this time I actually have an addition to add. :) The VW air cooled engines are actually air cooled/oil cooled. They actually have a oil cooling tower in the fan shroud assembly. You can increase the cooling by adding an external oil cooler as well. This increases the oil capacity by ~ 1 - 1.2 quarts depending on the system, as you mentioned. It is a common practice in hotter climates and racing.
I’d imagine that friction is a pretty small amount of the total heat rejected by a typical engine. Heat absorbed from compression and combustion will be the lion’s share of heat rejection.
Superb vid again. Excellent graphics and, as we have come to expect, clear and brilliantly thorough explanation. Also particularly nice to see the Suzuki engines and oil coolers pictured: I used to have a GSX-R1100G slab-side with the engine being talked-of in the vid (they have long-since gone to water). It was certainly light compared to its direct contemporaries, but I think I recall Suzuki claiming it as running cooler etc. If so, they must have been comparing against air-cooling only, as it ran a good deal hotter than any water-cooled bike I ever had, even at the time! (Still one of my faves...)
He didn’t say it directly but did imply that running lean makes things run hot. I just want to put out there that very clearly running lean DOES NOT MAKE YOUR ENGINE RUN HOT. Engineering Explained has an amazing video that breaks down the whole situation. The TLDR version of EEs video is running leaner then what your currently at (usually 12-10:1 afr) will mark things hotter until you hit 14.7:1 and then it cools back down and once your at like 16-20:1 your actually running really cool as well. I really like this video over all its very informative and well put together I’m not trying to hate on D4A I just want clear accurate information available to everyone.
Good video I have a air cooled Harley Davidson. Its amazing to me the air keeps the engine within operating temperature. I prefer the look of air cooled engines on bikes. No big plastic parts, rubber pipes or shrouds covering radiators attached to the engine cluttering the space. Simple and clean.
Rich mixtures in air cooled engines: In aircraft engines this was done during take-off and full power to cool the engine, as was explained. It was said that the flames from the (very short) exhaust pipes due to the excess fuel burning outside the engine could be up to 2 feet long! But once the throttle was pulled back the mixture was set to optimum, to have better fuel consumption.
Air cooled fan here! I love this System. Sincerely, every system has disadvantages, we need to choice one who has disadvantages that are not bad for us.
Great video as always, but are there really less parasitic losses on electric water pump compared to directly driven one? I'd expect that the main reason to use one is to allow cooling of the turbo and rest of the engine even after it is turned off.
@Andrew Ross But that's the thing, isn't it - you need a power source for the electric pump to work and how else do you get it than with an alternator which introduces a mechanical parasitic loss. Except in the case of the pump being electric, you not only lose the power needed to power the pump, you also get additional losses from the inefficiency of the alternator and the electric motor that powers the pump. So driving the pump directly will always be more efficient.
That's not true... The alternator load vs the water resistance on a belt drive is minuscule were talking 1-3hp... The advantages of an electric water pump are being able to cool the engine more at idle, low engine speeds and while the engine is not running... But for all out performance its a wash
Operating RPM plays a big role in answering your question. Mechanical water pump RPM varies with engine RPM, and a design optimized for stop and go traffic at 700 RPM will have measurable losses around 7000 RPM. Optimized for 7000 RPM won’t circulate enough coolant at 700. At relaxed traffic speeds it probably isn’t going to be noticeable to the owner, but manufacturers need every little bit of efficiency to reach MPG goals. On a race car the extra 5 to 20 horsepower can be worth the increased cost and possible supporting modifications to make an electric water pump work.
I suppose it is because it is decoupled from the engine rpm and it could be servo controlled to hit a desired temperature. Like EPS. It is not just the turbo, the engine can get heat soak once switched off. The pump is going at a rate that can empty a swimming pool in relatively short order, then you go to zero on switch off.
I went in to this video just cause I was bored not thinking I was goin to learn, but I did. I thought oil cooled motors were basically just air cooled but they just passed through a radiator on the path to lubricate, i didn’t realize they had cutouts for the flow as well. Thanks for that knowledge
The heat of combustion is by far the biggest source of heat in an internal combustion engine - friction accounts for about 5% of heat generated in an engine. It is possible, at ambient temperatures, to only convert about 25% of the combustion heat into mechanical movement. This was first theoretically understood by Léonard Carnot. The rest has to be dissipated. Typically about 40% of the heat of combustion goes into the exhaust gases, 30% into the cooling medium (air, oil or water), 5% into friction, and the remaining 25% as mechanical energy.
Efficiencies vary in engines with some diesel’s getting near 50% efficiency mainly because the fuel has more energy contained inside and less heat is wasted and actually used to move the vehicle. Gas is typically 25- ~35%
@driving 4 answers Largest downside of air, oil and hybrid air/oil cooled engines is by far Volumetric Efficiency (VE). I'm about to condense a lot of Thermodynamic and Fluid Dynamic information rather quickly, so stick with me: 1. Specific Heat Capacity is the ability of a fluid to absorb or transfer heat per unit mass, usually measured in British Thermal Units per pound mass/kilogram, or BTU/lbm BTU/kg. 2. Cylinder oil film thickness decreases exponentially as piston mean speed increases. 3. A combustion chamber/cylinder at a relatively colder temperature has a lower absolute pressure, meaning that there is a larger pressure differential between the cylinder and the intake tract as the intake valve starts to open. 4. As HP and Torque output per liter increases, the use of a fuel as an additional heat sink becomes more important than the fuel simply being a source of combustion. I have a 2005 Ducati 800 SuperSport, which is an 803cc V-twin SOHC with a hemispherical combustion chamber. From the factory, it makes ~ 74.5 HP at 8250 and 70 NM at 6250, which are respectable. But when put through a horsepower calculator (which you can find at this URL: hpwizard.com/engine-horsepower-calculator.html ) you'll soon see that at 100% VE, this engine should be making 88.82 HP, meaning that the engine itself is not at 100% VE, but rather 91%. And this is under ideal conditions where each cylinder is receiving uniform adequate airflow, which is not always the case. The higher the engine speed, the more drastic the difference becomes. All other things being equal, an equivalent engine set with HP peak at 12,000 RPM will make ~ 130 HP if water cooled, but only 106 HP if remaining Air/oil cooled. A noticeable side effect of air or hybrid air/oil cooling is that fuel consumption is higher than in water cooled examples, primarily due to statement 4 above. For reasoning as to why that is, see this video: ua-cam.com/video/aDSZhy551bo/v-deo.html , which goes into further detail on tuning as far as spark timing vs fuel metering. Keep in mind that air cooled engines tend to have hotter combustion chambers than their water cooled compatriots due solely to heat dissipation dynamics, thereby resulting in higher combustion chamber absolute pressure and lower differential pressure. This can be explored by watching Motor Trend's Engine Masters video 'Heat Kills Power - The How and Why' (Season 4, Episode 43) www.motortrendondemand.com/detail/heat-kills-powerthe-how-and-why/35777/772 And last but not least, in an engine cooled by anything other than water, oil comes into the cooling equation regardless of whether or not it's a dedicated system in the engine's design. Also keep in mind that per statement 2, the oil film thickness decreases exponentially as RPM increases, meaning that the more power you produce (and the higher you spin the engine) the worse the oil's capability to remove heat from the cylinder/piston underside *greatly* decreases, and it's not a linear relationship. Per statement 4, air and oil cooled engines require more fuel introduced into the cylinder to increase the overall capacity of the heat sink, leading to lower fuel mileage in order to maintain reliability and not cause overheating.
This was an informative, and very compact video, packed with useful info. The sponsor spot was in a good place, but most importantly, the green background really felt good on the eye. Edit for spelling errors
Hey D4A, really enjoying your videos. You could do a video about different petrol fuels, E5, E10 and E85 and what the difference is, how it affects combustion, when to use what and so on. I guess that would be quite interesting.
I first realised this with gaming computers - you can only get maximum performance out of your hardware by running water cooling. It's not simple or cheap, however. Great video!
My old 2006 Honda CB600F 599/Hornet was a liquid cool with an oil/coolant heat exchanger. That bike used 4liters of oil. First time I changed oil on that bike I was surprised that a 600cc bike used as much oil as my 1991 Acura Integra 1.8liters.
@@sking2173 yeah so do most all motorcycles, minus Harley, MotoGuzzi, and a few others. None of the other motorcycles I have ever had required as much oil. Even larger more powerful bikes use less.
A major drawback of air cooling is that cylinders have to be spaced further part on multicylinder engines to allow room for fins. This makes the engine longer/wider and thus heavier. Crankshaft has to be longer thus more flexible and then must be made heavier.
Just a minor correction, engines not only create some heat from friction but the brief moment of combustion creates a ton of heat. That’s why the top end of the engine around the cylinders and exhaust headers will be hotter than the lower end despite friction still existing in the crank and other parts. Other than that, the video explains everything well.
In saying that water cooling is the most effective option, i would like to state the truly most effective cooling is the combination of both oil cooling and water cooling. Cooling oil helps with keeping the oil in good condition, not allowing it to get too hot and start to burn and discolor, oil cooling is also considered nessesary when force induction is present on the engine as that can increase engine temperatures, cooling oil can also be benifical to engine longevity as the hydraulic effect of cooler oil is more resistant to dispersing at high pressures compared to hot oil.
sacs was a ww2 aircraft receipt applied in a milestone for superbikes , the gsxr sacs series. Very reliable way to cool the engine and this is the reason that sacs gsxrs are widely used for drag races and not the water cooled editions. Another simple way for cooling was introduced by Kreidler florets in the beginning of 1960 for 50cc mopeds and the same cooling idea was used from yamaha in some underbone two stroke 125s. They use a ventilator which was mounted directly in crankshaft . You can drive your moped in first gear for hours without a problem . The same principal used from chainsaws. The widely use of water cooling become for trade and marketing and mass production reasons.
Thanks for educating me, I knew the original Porsche 6 had a enormous amount of Oil in the engine, now I know why. When Tucker starting using the Hughes Helicopter engine they first add a water jacket to aid in cooling
I had a Suzuki GSX-R 750 1988 streetfighter. Needed to build the engine again. Too much abuse for a 70k driven bike 😂 The Air/Oil 1100 GSX-r my dream bike. After the new ZH2. Now on my second Z1000.
I never thought all that much about my Suzuki bandit having an oil cooler but the details were even cooler than I thought. Great video, another interesting video with some new information.
Great video with much detail and simplicity of information digestion. I’m surprised you didn’t discuss how oil or liquid cool radiators needs a way to mimic air blowing into it while stuck in traffic or idling on a hot day which is where the radiator fans come in. I was so shocked not to see it discussed but still a great video none the less!
One small correction about evaporative cooling. Cooling occurs because water vaporizes (evaporates) taking its heat with it. The hotter it is, the more quickly it vaporizes.
Okay but wait a minute - I would've thought that friction, when managed with a good oil (i.e. film of oil) would be rather minimal - & that by far the largest source of heat in an engine is combustion heat! This to the extent that diesels produce less heat than petrol - not because of any difference in friction, but because of greater combustion efficiency (i.e. more kinetic energy produced, & less heat). Is this dude April fooling us or sumthin'!?
Some American sprint cars run methanol mixtures in the 3.5:1 to 4.8:1 ratios, and therfore have quite small radiators, and cooling systems, because the latent heat of vaporization quality of methanol. A more extreme example of this is a top fuel dragster, which under full load, run AFR mixtures of 1:1, extremely rich.
You say you cannot control the cooling of air cooled. The vw beetle had a thermostat that shut off air flow over cyl until engine reaches operating temp. In the 1940s.
Yes that single example of shutting off only a part of the airflow refutes the thousands other air cooled engines that do nothing and my argument of "how the fins are always there and air is always there". Air cooling is not a closed system thus all attempts at its control are far less effective than in closed systems employing liquid cooling.
I love and enjoy your videos very much!! As physicist I'm of the opinion that in the present video the specific heat capacity, J/(K*kg) could explain matters better! Thanks a lot for your nice work!
7:39 No, Deutz D2011 is only oil cooled engine, has no air cooling. Pure oil cooling allows engine to run at temperatures above usual, it can not boil easily. Despite not being large, D2011 has about 18L of oil in cooling system. Deutz is company that made first Diesel engine for Rudolf Diesel, company where Benz, Maybach, Bosch and L`Orange learned their trade.
excellent video as always, however I think a more accurate unit of measure for heat capacity is J/kg K (or kJ/kg K) , which would indicate the amount of energy required to heat one kg of matter by one Kelvin. it obviously takes more energy to heat a larger amount of matter by the same temperature difference
I think a proper oil cooler with bigger radiator( like for liquid cooler) along with radiator fan or fans is what needed the most. Nowadays fan is omitted, small radiator etc are convention,to cut cost in smaller cc engines. Liquid cooler is good,but maintenance should be proper or else coolant mixes with oil and that for me is the greatest disadvantage of oil coolers
So the heat generated in an engine is from friction? How come a car going downhill while breaking on the engine doesn't overheat? I think the primary source of the heat comes from the combustion process.
Most of the heat is from the burning of fuel. And that’s why the top end of the engine will be hotter than the lower end because that’s where the power is made. That’s also why the cooling system becomes hot like almost boiling temps and under pressure. It’s like putting a pot of water on the stove.
Seems like oil/air cooling is the best for regular vehicles. minimal added parts. minimal added complexity. if heat capacity is an issue, just increase the flow and widen the radiator. Still more optimal than a massive secondary water system. and there is no need for only 1 flow path for oil, and no reason to not have a thermostat on the cooling loop. seems like water is only needed when you have high horsepower or forced induction
The problem of air cooling can be solved by making arc'ed plate to direct air to the back of engine, although this technique would make your speed "slower" only abit
You didn't directly say that lean tuning results in high temperatures, but you didn't state that mixtures lean of stoichiometric run cooler in a similar manner to how they run cooler rich of stoichiometric. Lean of Peak tuning ("peak" referring to EGTs which are at their highest at stoichiometric) is used in air craft and... people who know about it and have a reason to use it. I used it for years tuning carburetors on air and water cooled automotive engines. Cooler temps, better fuel economy (at the expense of some power, which is the down side), and better throttle response. Also good for emissions, and I've never seen a downside over many cars and years aside from the reduced power (which can be tuned back in at higher loads to get it back when you need it).
I think you will find the fact that we are igniting a fuel/air mixture several thousand times per minute contributes to the heat we have to deal with, especially in the heads...
The only 'real" distinction as to wether an "air cooled" engine is actually oil cooled or "air cooled" is by how much of the heat extraction is done by the oil or the air. Even in air cooled aircraft, the fraction of heat dumped from the heads by air is very close to the amount extracted by the oil, and totally depends on wether the engine has spray oil piston cooling or not as to wether theres more cooling done by the oil or air flowing over the heads. In all cases, the most, by far is the heat rejected by the exhaust! The fractions that I remember are 13% rejected by the air, 10% from the oil, and 40% out the exhaust. More aggressive usage of "oil cooling" can get upwards of 30% of the heat extraction from the oil, (thats what Porsche was able to do), but this requires 15 quarts of oil and humongous oil coolers. Probably a better way to procede is to stop so much of the heat of combustion from getting to the heads and block.
> to stop so much of the heat of combustion from getting to the heads and block. long stroke, double pancake shape ( HEMI ), high RPM ( the longer you wait, the more heat goes into the walls ) => fast piston speeds. Central sparkplug protruding a lot from the roof. A single exhaust valve has a little less surface area .. at least rocket engine like to have less but bigger nozzles. The thin walled exhaust pipe needs to start immediately behind the valve stem ( two exhaust valves: Y combination a welded pipes). Now tight bends in the headers. Extractor headers to pull the heat away. No turbo. 3 cylinder inline engines or hot vee to keep the heat at one place.
@@63turbo In the chamber we need to cool the oil on the walls. But you sure are correct for floor (piston ) and roof ( valves where not touching the seat ). I am all for Ethanol/Methanol and high compression, but water?? I am unsure about turbulence. Can we have so that it stays away from the walls? Squish areas seem bad.
@@ArneChristianRosenfeldt Water has a infinite "octane rating", and is really cheap compared to any fuel, especially these days. Adding alcohol to water makes it easier to evaporate. Both the piston and combustion chamber are the main sources of heat input, and at the point of maximum heat and pressure, (12 to 16 degrees after TDC) the cylinder walls are an insignificant source of heat transfer, because theres so little area at that point in the cycle exposed to the heat, and because the cylinder walls are usually made of something that is a relatively poor conductor of heat anyways. The more efficient the engine is, the less heat there is to get dumped into the cooling system, the less sophisticated the cooling needs to be!
@@63turbo Especially with oversquare engines and the firewall: The sliding surface (for the piston rings) is only exposed after 10 mm travel. Still, the flamefront reaches the oily surface about at that time ( last to burn at 20° after TDC ). Fortunately, pressure goes down from there and adiabatic cooling sets in. And yeah, less pressure means less molecules per area which imping on the poor surface. Just please keep the piston surface flat ( vertical valves => a reason to use 4 ). And the roof also flat so that the piston or valves do not need to compensate with bulge. I wonder if natural oxidization / carbon deposite already creates a heat barrier. For me, Ethanol is water+gasoline in a single molecule. Only one tank, one pump. Water should stay in the water-cooling jacket. Rust is a problem. With relative hot roof and top, it becomes important that the fresh charge is not too turbulent to not suck the heat out of there before the compression. So squish area is better and 2 intake valves. And generally large cylinders. Combined with the high piston velocity and the specced power (in a hybrid ): 3 cylinder engine like BMW i8 .
Most of the heat doesn't come from friction, but comes from the thermodynamic inefficiency of the engine. About a third of the fuel energy is transferred to the metal of the engine (and then the cooling system) rather than doing work on the piston, and another third is lost in the hot exhaust gases.
Some Volkswagens had oil coolers but they were primarily air cooled but still worth noting. I prefer oil cooling if you don't have liquid cooling and the simplicity of oil cooling is better to be then liquid or air cooling in a compact space.
I decided to try out a non-white background as some viewers say it's hard on the eyes in the dark. So what do you think, this background or the usual white?
I really like the new one, its very fresh
I like this background too.
New one is even visible
The new background is nice and easier on the eyes
Looks good.
When I was trained as an aircraft engine fitter, one of the first questions we were asked was 'what does the oil do?' and we were told that apart from lubrication it was used to cool the engine. With some large air-cooled aircraft engines the oil tank itself was 24 gallons or so and even though these engines used a lot of oil, the oil was cooled by an oil cooler and also by air flow around the tank. Notably gas turbine engines do run hotter in the turbine area but do not use the oil to cool the parts very much. The oil is often used to heat the incoming fuel as kerosene is not good at very low temperatures. However these turbine engines have very small oil tanks, normally only a gallon or two. As they don't use much oil, this is fine. Oil in modern turbocharged engines is also used to cool the turbine and compressor bearings but many of them also use water cooling of the turbocharger. These are especially useful on shut down where the oil can boil in the bearings and cause damage.
But you are correct in saying that eventually the engine and its parts are cooled by ambient air.
For my Private Pilot License, I learned that oil:
- lubricates
- seals
- cools
- removes contaminants
There is a point in which oil is no longer sufficient for cooking either.
After that the most common method is liquid cooling with the fuel. This is jet and rocket territory now but most turbines have a cycle to bring fuel through the engine to cool the turbine as well. Mainly again, in very very powerful turbopump engines and the like. Well past oil at that power level.
@@olafzijnbuis Beat me to it.
Yeah learned that in high school mechanics class.
in gas turbine engines the oil is pretty much only to remove heat from the bearings, it's all ball and roller bearings so there is no sliding friction. The oil is also very thin
aircraft air cooled engines are someting special because air cooling is not the best choice: at climb at full power is the cooling too low because low speed, at level flight is the cooling perfect but the badest moment is the descend before landing: oil is very hot, the engine is reduced to idle, then the cooling is much to high= the pistons are grow from the oil heat and cylinders shrink due to the airflow and the low heat in the combustion chamber= high risks to size the engine.To avoid this, are air cooled engines made with very large gaps between piston and cyclinder, this increase the overall oil consumption and increase the blow back in cold condition (and make the engine difficult to start in cold condition). A liquid cooled engine avoid such problems because a much better t° regulation, this explain why air cooled engines tend to disapear because they emissions are much higher on such engines because oil consumption+ run rich to avoid knoking...
In the 80's. There were two 911SCRS rally cars in the middle east. One was a factory car, the other a prodrive. The fatory 911 used to overheat in the Gulf rallies. Prodrive simply installed a huge oil cooler, problem was solved.Car won the championship for multiple years.
well the more hotter the oil is it give less protection and lubrication that make more heat and create heat loop. Breaking the oil film loosing compression and power.
I've always wondered about super cooling an engine. I know it's not cost effective but if you could use liquid nitrogen cooling for the exhaust and cylinder head combustion chamber. And for that matter if you could use it on intercoolers for turbos and blowers where it ran through the equivalent of a intercooler that fits in a area below the throttle body so the intake air is cooled to close to 0°C before the fuel is injected.
@@theEVILone0130 That will be very interesting to see, I hope it's tested one day!
@@theEVILone0130Think about the drawbacks.
If you carry Nitrogen as a coolant, it would have to have a compressor and a complex system to get low-pressure and high pressure zones to obtain said cooling and recycle the nitrogen.
And if you just release the Nitrogen, you'd have to carry a heavy tank to store it, and be recharging the Nitrogen constantly.
Sounds like a cool concept though.
Some nuclear reactors used by soviet submarines went as far as to use molten metal as the fluid for their cooling system for the sake of compactness. This meant that they could under no circumstance stop the reactor during the submarines' lifespan or else it would solidify.
That sounds insane. Is there any article, that can give me more information on that?
@@Franko384 en.wikipedia.org/wiki/Liquid_metal_cooled_reactor
@@juanordonezgalban2278 thank you very much sir
Usually it was sodium or some other alkali metal. There were also sodium-cooled valves used in piston engines, which are not so common nowadays.
What the actual fuck
I like the relative simplicity of an oil cooled engine like the one in my 2001 Bandit, the fact that leaking gaskets will never result in water contaminating the engine oil, and that there are no water pumps or coolant hoses to corrode or fail. An ideal engine for me would be an oil cooled, fuel injected triple with a thermostat and a fan.
An oil cooled engine requires a higher volume oil pump and the increased temperature change of the oil leads to faster degradation. Almost all oil cooled engines have a thermostat.
Ideally for power you need to go the liquid cooling path or if reliability is your thing then air it is. Oil is something in between.
@@soldrier Degradation only for the oil. I'm running a suzuki oil burner on 15 psi of boost putting down 250 wheel - 250% of stock power. Oil lasts the same, and the only cooling mod is a larger 19 row racing transmission cooler repirposed to replace the stock one. I had the opposite problem where in fall the bike struggled to keep operating temp from the larger cooler. AFAIK no SACS motors used thermostats, not the 1157s 1127s 750s ect. EXTREMELY reliable, you can be pissing oil and aslong as it's topped off there's no issues. It's also better to not have to worry about deck types and headgasket issues without the waterjackets, never underestimate an old oilboiler.
@@soldrier Something in between suits me fine :)
@@remedia1200 Yes indeed, only oil degradation failed to mention that. Now I don't know what engine we are talking about. I'm only aware of late 80s early 90s sport bikes being oil cooled. I mean in an essence all engines are oil cooled even the 2cv had a radiator. You're right about that it's harder to reach operating temps :)..
Now from an engineering standpoint. Having more oil to cool the engine only leads to slower warmup time influencing emissions. Wear in modern engines is not so of a problems as UA-cam mechanics would lead you to be. Also heat in an ICE is highly localised. Yes you can use your bike at 250% power but for how long? Those new castings, open block designs etc. While bad for reliability, are an excellent solution to keep heat down on high powered engines. No wonder nothing else caught on. :)
@@soldrier you'd be surprised - i'm running low number compared to some. There are 400 -500 hp bikes ou there that have been running quarters for years. Good top fueling/cooling with watermeth, rich mixture, intercooler and oil cooler makes them very happy under boost.
As usual your videos are great. I'm a mechanical engineer but since I'm from Italy this videos helps me to learn A LOT of technical words about engineering. Your videos are clear even for a beginner like me 🤣 Thanks for sharing your time with us and create these masterpieces!
"but since I'm from Italy this videos helps me to learn A LOT of technical words about engineering." Same with me from Poland :D
Ti consiglio il libro "motori endotermici" di dante giacosa. Un pò datato ma molto utile
Are you a mechanical engineer OR a beginner?
I remember talking to a Porsche 911 930 owner. He told me, that the engine is oil-cooled, not air-cooled, because there is 14 liters of oil in the system. When normally in water-cooled 6 cylinder engines it's 6-8 and maybe sometimes up to 10 liters of oil.
I like the comment ‘it’s blurry’ between Air/Oil cooled. I don’t think it has anything to do with there being an oil cooler. The Porsche 911 is both oil cooled and air cooled.
I think you are exaggerating those oil capacities by a few L.
Those 3l Porsche engines are air-cooled. Compare a 6l small block uses ça 5l of oil, 6l if it got an oil cooler, 7l of oil if external filter and external oil cooler are present. 9l if you add a vaccum reservoir for the oil. I build my street racing small blocks with 7l capacity and a very flat oil pan and increased the water circuit by 4l with an external tank riding in the airstream. It's essentially a dry sump and heat radiation from the pan is lower. A finned sump cover could help but in my climate this was not needed. My cars run cool on a 35 Celsius day.
14l oil capacity on a Porsche means that the engine has some serious engineering defects. That's why I stayed away from racing Porsche and my motors and cars are simply better than what Porsche does. 500hp at 5600 and 900kg is fun. A 1800kg Porsche with 400hp/7000 is boring.
@@alienpoker Yup, air for cylinder heads, oil for block.
@@3800S1 No, my 911 from 1977 holds 13 litres.
I’m a BIG fan of your channel. Your automotive presentations are the best balance of accuracy and accessibility on the web.
Having said that, I was surprised to see what I consider a bit of a stumble in this video (engine cooling). Please tell me if you agree with these criticisms of this episode:
Combustion, not friction, is the major source of engine heat.
Lubrication, not cooling, is the major defense against friction.
The function of engine cooling is to remove combustion heat from the engine.
Properly lubricated piston rings don’t create engine-damaging heat, rather, they transfer combustion heat to the cylinder walls which are cooled by air or liquid.
So, I think your focus on friction in relation to cooling is misplaced and potentially confusing to the uninitiated. No amount of cooling will save a poorly-lubricated engine.
Please keep up the good work producing informative, no nonsense automotive videos!
8:57 Classic British bikes used a similar dual oil pump, but the high volume side was to scavenge oil from the sump to the oil tank. In my 1966 Norton 650SS high pressure oil is directed at the underside of the piston crowns to provide cooling, with the heat being dissipated to some extent by the oil tank.
I really wasn't expecting this video to be that dense of information and everything to be explained so well. Really good content keep up the good work!
I've been a subscriber for a while now. Your videos lately have been top notch! This channel will continue growing fast if you just keep up the good work.
I already knew this stuff, saw the video in my recommended and decided to watch out of curiosity and im positively suprised. Everything is explained simply and clearly. so much info for a 14 minute youtube video, it would take me likely something closer to and hour to actually explain all this stuff to someone who doesnt know it. thumbs up.
5 more advantages of AC motorcycle bikes, not mentioned in the comments (yet) are:
1) The weight difference - a liquid cooled motorcycle will weigh more.
2) An engine being a complex mechanical machine. You can both hear and listen to the motor more acutely. A water jacket in an engine is a sound insulator. Some would say this is a good thing as liquid cooled engines are quieter than air cooled engines, I just disagree.
3) In air cooling systems, the engine is not subjected to freezing issues (I know, I know... liquid coolant, has anti-freeze properties).
4) No danger of coolant leakage or low level in air cooling system.
5) An air-cooled engine can take up some degree of damage. A broken fin does not affect much while a hole in the radiator may stop a water-cooled engine.
Yeah, OK... I'm old school.
less appreciated these days is the difference in consequences of overheating an air cooled engine vs a water cooled one. If a water pumper ever over heats bad enough the block and heads are usually toast... you are usually "done" driving until the engine is fixed or replaced.With an aircooled engine, all that is required is to get over to the side of the road, let it cool down and you are on your way again.
So, an engine making more noise is an advantage? Are you a sadist or something?
@@caty863 Its an advantage if you like the sound its making, and is a disadvantage if not. Its for the same reason people put louder than stock mufflers on or, why the stereo has volume control and a off button.
Its the sound of music to some, (like me!) and a "reason" to own a waterpumper for others ua-cam.com/video/VKMGJJ4IyQ4/v-deo.html
@@63turbo Thanks, could not have said it better myself.
I had a Suzuki that go around the problem with uneven cooling on the rear of the engine on an air cooled engine in an interesting way - the front cylinder was air cooled, but the rear cylinder was air/oil cooled.
I have a DR650 now, and it has a weirdly large oil cooler for a 650cc engine. But that thing just won't overheat.
I'm really digging the new background. I'd love to see more of this.
Always something of value to learn from your excellent presentations. I catch very few misstatements very occasionally and mostly pick up some facts or perspectives. Thanks. You start this presentation with a curious attribution of friction as the primary cause of excess heat. The rest of your presentation shows you know that combustion produces the lion's share of excess heat--the sixty to seventy percent inefficiency of the cycle. Friction's contribution is miniscule compared with that of combustion. In 1971, in a first-year thermodynamics class toward my mechanical engineering major, the professor asked this very question, that is, where does an internal combustion engine's excess heat come from. One of us students immediately answered, "friction." I vividly remember the professor's astonishment at our ignorance. He said something to the effect that if friction were producing anywhere near (within two orders of magnitude) the heat of combustion, the metals subject to such friction would quickly melt, bearing in mind that the local interface of frictional heat generation is instantaneously very small. Remember, too, that gas flow and introduction of evaporative fuel (as you detail) carries off most of the excess heat of inefficiency. Still, as you show, engine cooling is concentrated around the combustion chambers and exhaust ports. Along these lines, Rotax 900 series aviation engines utilize a hybrid cooling system; liquid cooled heads and finned, dry cylinder barrels sufficient to remove the residual heat of combustion carried into the cylinder walls (and, ok, that little bit of ring/wall frictional heat).
Another thing i found strange is that he mentioned the fuel evaporation cooling effect, but not that the flame of the rich mixture itself burns cooler
Your comment is to the point, it was really a bizzare intro stating that friction is key heat generator in the internal combustiin engine. Total loss of credibility
Totally agree with your comments about heat sources in ICE. But “Excess heat of inefficiency”? What are you trying to say on this?
I love that you greet us as Engineers, I’m really a technician but I LOVE how educational your content is
What most people do not realise is that the oil not only lubricates the engine, it is also a very important coolant within the engine, whether air or water cooled...
Friction is minor heat source, these are combustion engines and that is the main source of heat. Air compressors get hot because of the compression, but the combustion engine compresses and then decompresses the air if there is no fuel and spark added, so the net Heat would be insignificant because the heat would transfer to the air it's self and therefore be exhausted. the movement of air would be cooling. But, when you add Fuel and Then combust the mix by spark, the actual heat coming from this combustion is what runs the engine and an unavoidable consequence is heat. That is the main reason why most ultra efficient engines today have a energy to work conversion of less then 50%, that means that the other 50% is heat and other forms of energy that do not translate to work, or in other words locomotion.
Correct. Combustion is a good way to move heavy stuff but creates a ton of wasted heat energy that has to go somewhere.
This man somehow makes my ADHD brain keep focused for more than 2 minutes on a complex engineering topic, puts it in a way I actually understand (I'm quite stupid) and makes it enjoyable in the process.
Most of the heat in the engine is from the combustion... Compressors that is basically the same as an engine but without the combustion do not get nearly as hot as a similar sized engine.
Friction is only a miniscule percentage of the heat rejection of an internal combustion engine. This kind of ignorance of basic thermodynamics drives me crazy.
And most of the heat will be at the top end of the engine due to combustion being quite hot once warmed up. Friction heat is indeed minimal.
Interesting and easy to understand video like always. I have owned several motorcycles and scooters since I was young. Some of them were air cooled, other water cooled... but I loved them all! I would like to share two ideas: some scooters have a special type of cooling system, "forced air cooling system". The forced air is provided by a small fan moved by the engine. The old Vespino had that interesting system. And many current scooters use that technology. The Spanish engineeres of the humble Vespino were very creative and invented the continously variable transmission. That mechanism is nowadays very common in the scooters and even cars. Nobody knows that this transmission method was created for this low displacement vehicle.
Fantastic video. The other disadvantage of air cooling (and advantage of water cooling) is increased engine noise as the cylinders aren't surrounded by a water jacket which acts to muffle combustion noise.
Great video, I didn`t know that there were engines actually circulating oil around the combustion chambers. I would add that the biggest advantage water has over oil as a cooling fluid is it`s thermal conductivity. Combined with the thermal capacity it makes water about 8 or so times better as a cooling medium. Keep up the great content, I am learning tons from each of your videos.
This is my new favorite channel. There is so much information in these videos
I enjoy your videos and this time I actually have an addition to add. :) The VW air cooled engines are actually air cooled/oil cooled. They actually have a oil cooling tower in the fan shroud assembly. You can increase the cooling by adding an external oil cooler as well. This increases the oil capacity by ~ 1 - 1.2 quarts depending on the system, as you mentioned. It is a common practice in hotter climates and racing.
Very informative for a guy that just bought his first motorcycle and didn`t realize that it doesn`t have a fan until he brought it home.
I’d imagine that friction is a pretty small amount of the total heat rejected by a typical engine. Heat absorbed from compression and combustion will be the lion’s share of heat rejection.
Exactly
Correct.
Superb vid again. Excellent graphics and, as we have come to expect, clear and brilliantly thorough explanation.
Also particularly nice to see the Suzuki engines and oil coolers pictured: I used to have a GSX-R1100G slab-side with the engine being talked-of in the vid (they have long-since gone to water).
It was certainly light compared to its direct contemporaries, but I think I recall Suzuki claiming it as running cooler etc. If so, they must have been comparing against air-cooling only, as it ran a good deal hotter than any water-cooled bike I ever had, even at the time! (Still one of my faves...)
He didn’t say it directly but did imply that running lean makes things run hot. I just want to put out there that very clearly running lean DOES NOT MAKE YOUR ENGINE RUN HOT. Engineering Explained has an amazing video that breaks down the whole situation. The TLDR version of EEs video is running leaner then what your currently at (usually 12-10:1 afr) will mark things hotter until you hit 14.7:1 and then it cools back down and once your at like 16-20:1 your actually running really cool as well. I really like this video over all its very informative and well put together I’m not trying to hate on D4A I just want clear accurate information available to everyone.
Good video I have a air cooled Harley Davidson. Its amazing to me the air keeps the engine within operating temperature. I prefer the look of air cooled engines on bikes. No big plastic parts, rubber pipes or shrouds covering radiators attached to the engine cluttering the space. Simple and clean.
Rich mixtures in air cooled engines: In aircraft engines this was done during take-off and full power to cool the engine, as was explained. It was said that the flames from the (very short) exhaust pipes due to the excess fuel burning outside the engine could be up to 2 feet long! But once the throttle was pulled back the mixture was set to optimum, to have better fuel consumption.
Air cooled fan here! I love this System.
Sincerely, every system has disadvantages, we need to choice one who has disadvantages that are not bad for us.
Great video as always, but are there really less parasitic losses on electric water pump compared to directly driven one? I'd expect that the main reason to use one is to allow cooling of the turbo and rest of the engine even after it is turned off.
@Andrew Ross But that's the thing, isn't it - you need a power source for the electric pump to work and how else do you get it than with an alternator which introduces a mechanical parasitic loss. Except in the case of the pump being electric, you not only lose the power needed to power the pump, you also get additional losses from the inefficiency of the alternator and the electric motor that powers the pump. So driving the pump directly will always be more efficient.
That's not true... The alternator load vs the water resistance on a belt drive is minuscule were talking 1-3hp... The advantages of an electric water pump are being able to cool the engine more at idle, low engine speeds and while the engine is not running... But for all out performance its a wash
Operating RPM plays a big role in answering your question. Mechanical water pump RPM varies with engine RPM, and a design optimized for stop and go traffic at 700 RPM will have measurable losses around 7000 RPM. Optimized for 7000 RPM won’t circulate enough coolant at 700. At relaxed traffic speeds it probably isn’t going to be noticeable to the owner, but manufacturers need every little bit of efficiency to reach MPG goals. On a race car the extra 5 to 20 horsepower can be worth the increased cost and possible supporting modifications to make an electric water pump work.
I suppose it is because it is decoupled from the engine rpm and it could be servo controlled to hit a desired temperature. Like EPS. It is not just the turbo, the engine can get heat soak once switched off. The pump is going at a rate that can empty a swimming pool in relatively short order, then you go to zero on switch off.
I went in to this video just cause I was bored not thinking I was goin to learn, but I did. I thought oil cooled motors were basically just air cooled but they just passed through a radiator on the path to lubricate, i didn’t realize they had cutouts for the flow as well. Thanks for that knowledge
The heat of combustion is by far the biggest source of heat in an internal combustion engine - friction accounts for about 5% of heat generated in an engine.
It is possible, at ambient temperatures, to only convert about 25% of the combustion heat into mechanical movement. This was first theoretically understood by Léonard Carnot. The rest has to be dissipated.
Typically about 40% of the heat of combustion goes into the exhaust gases, 30% into the cooling medium (air, oil or water), 5% into friction, and the remaining 25% as mechanical energy.
Efficiencies vary in engines with some diesel’s getting near 50% efficiency mainly because the fuel has more energy contained inside and less heat is wasted and actually used to move the vehicle. Gas is typically 25- ~35%
You make automotive educational content that's very easy to digest, and as a young car enthusiast I sincerely thank you for that!
@driving 4 answers
Largest downside of air, oil and hybrid air/oil cooled engines is by far Volumetric Efficiency (VE). I'm about to condense a lot of Thermodynamic and Fluid Dynamic information rather quickly, so stick with me:
1. Specific Heat Capacity is the ability of a fluid to absorb or transfer heat per unit mass, usually measured in British Thermal Units per pound mass/kilogram, or BTU/lbm BTU/kg.
2. Cylinder oil film thickness decreases exponentially as piston mean speed increases.
3. A combustion chamber/cylinder at a relatively colder temperature has a lower absolute pressure, meaning that there is a larger pressure differential between the cylinder and the intake tract as the intake valve starts to open.
4. As HP and Torque output per liter increases, the use of a fuel as an additional heat sink becomes more important than the fuel simply being a source of combustion.
I have a 2005 Ducati 800 SuperSport, which is an 803cc V-twin SOHC with a hemispherical combustion chamber. From the factory, it makes ~ 74.5 HP at 8250 and 70 NM at 6250, which are respectable. But when put through a horsepower calculator (which you can find at this URL: hpwizard.com/engine-horsepower-calculator.html ) you'll soon see that at 100% VE, this engine should be making 88.82 HP, meaning that the engine itself is not at 100% VE, but rather 91%. And this is under ideal conditions where each cylinder is receiving uniform adequate airflow, which is not always the case. The higher the engine speed, the more drastic the difference becomes. All other things being equal, an equivalent engine set with HP peak at 12,000 RPM will make ~ 130 HP if water cooled, but only 106 HP if remaining Air/oil cooled. A noticeable side effect of air or hybrid air/oil cooling is that fuel consumption is higher than in water cooled examples, primarily due to statement 4 above. For reasoning as to why that is, see this video: ua-cam.com/video/aDSZhy551bo/v-deo.html , which goes into further detail on tuning as far as spark timing vs fuel metering.
Keep in mind that air cooled engines tend to have hotter combustion chambers than their water cooled compatriots due solely to heat dissipation dynamics, thereby resulting in higher combustion chamber absolute pressure and lower differential pressure. This can be explored by watching Motor Trend's Engine Masters video 'Heat Kills Power - The How and Why' (Season 4, Episode 43) www.motortrendondemand.com/detail/heat-kills-powerthe-how-and-why/35777/772
And last but not least, in an engine cooled by anything other than water, oil comes into the cooling equation regardless of whether or not it's a dedicated system in the engine's design. Also keep in mind that per statement 2, the oil film thickness decreases exponentially as RPM increases, meaning that the more power you produce (and the higher you spin the engine) the worse the oil's capability to remove heat from the cylinder/piston underside *greatly* decreases, and it's not a linear relationship.
Per statement 4, air and oil cooled engines require more fuel introduced into the cylinder to increase the overall capacity of the heat sink, leading to lower fuel mileage in order to maintain reliability and not cause overheating.
My vespa px is rich as fuck for this reason
This was an informative, and very compact video, packed with useful info. The sponsor spot was in a good place, but most importantly, the green background really felt good on the eye.
Edit for spelling errors
Change is awesome when its good 👌🏽
Loved that you changed the background
There is so much afford in each of your videos, always a pleasure to see a new one uploaded.
What?
@@quinndenver4075 effort
The grammar and spelling is weak with this one.
@@MurCurieux true
I am no engine expert but I'd say that 90+%of the heat in the engine is caused by combusting the fuel
Hey D4A, really enjoying your videos. You could do a video about different petrol fuels, E5, E10 and E85 and what the difference is, how it affects combustion, when to use what and so on. I guess that would be quite interesting.
I first realised this with gaming computers - you can only get maximum performance out of your hardware by running water cooling. It's not simple or cheap, however. Great video!
Nope, that is not true, because it is the wrong conclusion. ua-cam.com/video/7VzXHUTqE7E/v-deo.html
Another great example of your teaching skill.
My old 2006 Honda CB600F 599/Hornet was a liquid cool with an oil/coolant heat exchanger. That bike used 4liters of oil. First time I changed oil on that bike I was surprised that a 600cc bike used as much oil as my 1991 Acura Integra 1.8liters.
The CB600F also uses the same oil for both engine and transmission lubrication ...
@@sking2173 yeah so do most all motorcycles, minus Harley, MotoGuzzi, and a few others. None of the other motorcycles I have ever had required as much oil. Even larger more powerful bikes use less.
A major drawback of air cooling is that cylinders have to be spaced further part on multicylinder engines to allow room for fins. This makes the engine longer/wider and thus heavier. Crankshaft has to be longer thus more flexible and then must be made heavier.
I had an 86 GSX-R 1100 I'm 6"2 it was a torture device 😆😆
Impressive how much he knows and prepares for his videos. Top notch expert.
This video is so interesting and well explained that I’ve even put lot of attention to the Squarespace sponsor ad included
Just a minor correction, engines not only create some heat from friction but the brief moment of combustion creates a ton of heat. That’s why the top end of the engine around the cylinders and exhaust headers will be hotter than the lower end despite friction still existing in the crank and other parts. Other than that, the video explains everything well.
Yeah, green is the go!
Another great video you utter champion!
In saying that water cooling is the most effective option, i would like to state the truly most effective cooling is the combination of both oil cooling and water cooling. Cooling oil helps with keeping the oil in good condition, not allowing it to get too hot and start to burn and discolor, oil cooling is also considered nessesary when force induction is present on the engine as that can increase engine temperatures, cooling oil can also be benifical to engine longevity as the hydraulic effect of cooler oil is more resistant to dispersing at high pressures compared to hot oil.
sacs was a ww2 aircraft receipt applied in a milestone for superbikes , the gsxr sacs series. Very reliable way to cool the engine and this is the reason that sacs gsxrs are widely used for drag races and not the water cooled editions. Another simple way for cooling was introduced by Kreidler florets in the beginning of 1960 for 50cc mopeds and the same cooling idea was used from yamaha in some underbone two stroke 125s. They use a ventilator which was mounted directly in crankshaft . You can drive your moped in first gear for hours without a problem . The same principal used from chainsaws. The widely use of water cooling become for trade and marketing and mass production reasons.
Thank you for another informative quality video. These videos make my sundays perfect. Looking forward for the next one.
Love the animations. Make it very easy to understand how internal processes work in engines. You always go above and beyond.
I own suzuki bandit….such a good engine
This channel is gold
Thanks for educating me, I knew the original Porsche 6 had a enormous amount of Oil in the engine, now I know why. When Tucker starting using the Hughes Helicopter engine they first add a water jacket to aid in cooling
I had a Suzuki GSX-R 750 1988 streetfighter. Needed to build the engine again. Too much abuse for a 70k driven bike 😂 The Air/Oil 1100 GSX-r my dream bike. After the new ZH2. Now on my second Z1000.
I never thought all that much about my Suzuki bandit having an oil cooler but the details were even cooler than I thought. Great video, another interesting video with some new information.
Cool video as usual, gotta love your chill and breezy explanations ;)
Thanks bro for this Detailed knowledge 🥰🥰🥰
Great video with much detail and simplicity of information digestion. I’m surprised you didn’t discuss how oil or liquid cool radiators needs a way to mimic air blowing into it while stuck in traffic or idling on a hot day which is where the radiator fans come in. I was so shocked not to see it discussed but still a great video none the less!
Your channel is excellent - thank you.
Another Gold Star...thanks...Looks better.
You even covered Suzuki's SOCS which were used on their older bikes and the new GIXXER 250, nice!
One small correction about evaporative cooling. Cooling occurs because water vaporizes (evaporates) taking its heat with it. The hotter it is, the more quickly it vaporizes.
Okay but wait a minute - I would've thought that friction, when managed with a good oil (i.e. film of oil) would be rather minimal - & that by far the largest source of heat in an engine is combustion heat! This to the extent that diesels produce less heat than petrol - not because of any difference in friction, but because of greater combustion efficiency (i.e. more kinetic energy produced, & less heat).
Is this dude April fooling us or sumthin'!?
Some American sprint cars run methanol mixtures in the 3.5:1 to 4.8:1 ratios, and therfore have quite small radiators, and cooling systems, because the latent heat of vaporization quality of methanol. A more extreme example of this is a top fuel dragster, which under full load, run AFR mixtures of 1:1, extremely rich.
Super clear and super interesting! Thanks a lot for the good work!
Great video, and nice graphics with well-sorted dialog.
You say you cannot control the cooling of air cooled.
The vw beetle had a thermostat that shut off air flow over cyl until engine reaches operating temp.
In the 1940s.
Yes that single example of shutting off only a part of the airflow refutes the thousands other air cooled engines that do nothing and my argument of "how the fins are always there and air is always there". Air cooling is not a closed system thus all attempts at its control are far less effective than in closed systems employing liquid cooling.
Very nice presentation of the subject! Good balance between illustration and narrative. Audio quality is a treat.
I love and enjoy your videos very much!!
As physicist I'm of the opinion that in the present video the specific heat capacity, J/(K*kg) could explain matters better!
Thanks a lot for your nice work!
i think that the numbers showed here were already specific heats, he probably forgot the kg part in the animation
Another advantage to water cooled engines is the cylinder to piston gap can be tighter because air cooled engines don't have as even cooling.
Because of you I am going to mechanic school thank u
7:39 No, Deutz D2011 is only oil cooled engine, has no air cooling.
Pure oil cooling allows engine to run at temperatures above usual, it can not boil easily.
Despite not being large, D2011 has about 18L of oil in cooling system.
Deutz is company that made first Diesel engine for Rudolf Diesel, company where Benz, Maybach, Bosch and L`Orange learned their trade.
Excellent upload, extremely informative, thank you. 👍
I have only watched a handfull of your vids which were good, you seemed to haved missed some important points early on but i will continue to watch
excellent video as always, however I think a more accurate unit of measure for heat capacity is J/kg K (or kJ/kg K) , which would indicate the amount of energy required to heat one kg of matter by one Kelvin. it obviously takes more energy to heat a larger amount of matter by the same temperature difference
Awesome video, thanks for the going so in depth on Air cooled engines
I think a proper oil cooler with bigger radiator( like for liquid cooler) along with radiator fan or fans is what needed the most. Nowadays fan is omitted, small radiator etc are convention,to cut cost in smaller cc engines. Liquid cooler is good,but maintenance should be proper or else coolant mixes with oil and that for me is the greatest disadvantage of oil coolers
So the heat generated in an engine is from friction? How come a car going downhill while breaking on the engine doesn't overheat?
I think the primary source of the heat comes from the combustion process.
Most of the heat is from the burning of fuel. And that’s why the top end of the engine will be hotter than the lower end because that’s where the power is made. That’s also why the cooling system becomes hot like almost boiling temps and under pressure. It’s like putting a pot of water on the stove.
Seems like oil/air cooling is the best for regular vehicles. minimal added parts. minimal added complexity.
if heat capacity is an issue, just increase the flow and widen the radiator. Still more optimal than a massive secondary water system.
and there is no need for only 1 flow path for oil, and no reason to not have a thermostat on the cooling loop.
seems like water is only needed when you have high horsepower or forced induction
Very interesting and helpful video, thank you for posting!
The problem of air cooling can be solved by making arc'ed plate to direct air to the back of engine, although this technique would make your speed "slower" only abit
You didn't directly say that lean tuning results in high temperatures, but you didn't state that mixtures lean of stoichiometric run cooler in a similar manner to how they run cooler rich of stoichiometric. Lean of Peak tuning ("peak" referring to EGTs which are at their highest at stoichiometric) is used in air craft and... people who know about it and have a reason to use it. I used it for years tuning carburetors on air and water cooled automotive engines. Cooler temps, better fuel economy (at the expense of some power, which is the down side), and better throttle response. Also good for emissions, and I've never seen a downside over many cars and years aside from the reduced power (which can be tuned back in at higher loads to get it back when you need it).
I love your videos by the way. What about coolant fluids that you can use instead of water?
Anyone else see the square space ad where the photography genius doesn't do weddings but only "takes photos of nice kids"
This was the first video that I saw from you. Result: subscribed!
I feel like iv5e watched so many of his videos. But I somehow don't know his name. Or else I'd recommend him for a Nobel prize. 🏆
I think you will find the fact that we are igniting a fuel/air mixture several thousand times per minute contributes to the heat we have to deal with, especially in the heads...
Great information. Well done
The only 'real" distinction as to wether an "air cooled" engine is actually oil cooled or "air cooled" is by how much of the heat extraction is done by the oil or the air. Even in air cooled aircraft, the fraction of heat dumped from the heads by air is very close to the amount extracted by the oil, and totally depends on wether the engine has spray oil piston cooling or not as to wether theres more cooling done by the oil or air flowing over the heads. In all cases, the most, by far is the heat rejected by the exhaust! The fractions that I remember are 13% rejected by the air, 10% from the oil, and 40% out the exhaust. More aggressive usage of "oil cooling" can get upwards of 30% of the heat extraction from the oil,
(thats what Porsche was able to do), but this requires 15 quarts of oil and humongous oil coolers. Probably a better way to procede is to stop so much of the heat of combustion from getting to the heads and block.
> to stop so much of the heat of combustion from getting to the heads and block.
long stroke, double pancake shape ( HEMI ), high RPM ( the longer you wait, the more heat goes into the walls ) => fast piston speeds. Central sparkplug protruding a lot from the roof. A single exhaust valve has a little less surface area .. at least rocket engine like to have less but bigger nozzles. The thin walled exhaust pipe needs to start immediately behind the valve stem ( two exhaust valves: Y combination a welded pipes). Now tight bends in the headers. Extractor headers to pull the heat away. No turbo. 3 cylinder inline engines or hot vee to keep the heat at one place.
@@ArneChristianRosenfeldt Thermal barriers in the combustion chamber and exhaust port + water/methanol injection works on anything.
@@63turbo In the chamber we need to cool the oil on the walls. But you sure are correct for floor (piston ) and roof ( valves where not touching the seat ).
I am all for Ethanol/Methanol and high compression, but water?? I am unsure about turbulence. Can we have so that it stays away from the walls? Squish areas seem bad.
@@ArneChristianRosenfeldt Water has a infinite "octane rating", and is really cheap compared to any fuel, especially these days. Adding alcohol to water makes it easier to evaporate. Both the piston and combustion chamber are the main sources of heat input, and at the point of maximum heat and pressure, (12 to 16 degrees after TDC) the cylinder walls are an insignificant source of heat transfer, because theres so little area at that point in the cycle exposed to the heat, and because the cylinder walls are usually made of something that is a relatively poor conductor of heat anyways. The more efficient the engine is, the less heat there is to get dumped into the cooling system, the less sophisticated the cooling needs to be!
@@63turbo Especially with oversquare engines and the firewall: The sliding surface (for the piston rings) is only exposed after 10 mm travel. Still, the flamefront reaches the oily surface about at that time ( last to burn at 20° after TDC ). Fortunately, pressure goes down from there and adiabatic cooling sets in. And yeah, less pressure means less molecules per area which imping on the poor surface.
Just please keep the piston surface flat ( vertical valves => a reason to use 4 ). And the roof also flat so that the piston or valves do not need to compensate with bulge. I wonder if natural oxidization / carbon deposite already creates a heat barrier. For me, Ethanol is water+gasoline in a single molecule. Only one tank, one pump. Water should stay in the water-cooling jacket. Rust is a problem.
With relative hot roof and top, it becomes important that the fresh charge is not too turbulent to not suck the heat out of there before the compression. So squish area is better and 2 intake valves. And generally large cylinders. Combined with the high piston velocity and the specced power (in a hybrid ): 3 cylinder engine like BMW i8 .
Most of the heat doesn't come from friction, but comes from the thermodynamic inefficiency of the engine. About a third of the fuel energy is transferred to the metal of the engine (and then the cooling system) rather than doing work on the piston, and another third is lost in the hot exhaust gases.
I love all 4 of my air-cooled engines.
On an oil cooled engine proper oil changes must be even more important with so many small channels to get clogged.
Thanks, I learned some new things !
Some Volkswagens had oil coolers but they were primarily air cooled but still worth noting. I prefer oil cooling if you don't have liquid cooling and the simplicity of oil cooling is better to be then liquid or air cooling in a compact space.
I'd love to see a detailed video on engine braking and how it works.
Compression. It’s as simple as that.