What size engines use air ,oil & water/antifreeze cooling? Why?

[DuciD03]

This came form another post for a slightly different question; it raises many intresting mechanical & engineering questions about duc engines; cooling, heat generated vs hp vs engine size ...

Why and what size Duc engines can effectively be air cooled; oil cooled and water / antifreeze cooled?. (question slightly revised to clarify se2809 at 8:30 pm pacific time)  

Further; is this limit is due to overheating of the cyl rings? At what temp is air cooled not enough?  I imagine its that traffic jam stop and go low speed in an Rome heatwave that there thinking about ... has anyone ever had an engine seize due to overheating???

So

What size engines have been engineered by Ducati  for air ,oil & water/antifreeze applications? Why use water as opposed to oil?  

by my recollection ....

air cooled; yrs? - 400; 600 620

Oil cooled; Yrs? - 750 ? to 02; 800 ; 900; 1k 1.1k - 2 valvers (and what about the oil cooled cyl jacket Nate mentioned; intresting)

water antifreeze cooled Yrs? Its related to the 4 cyl valves right?- 749? 848? 849? 916? 999? 1k etc

s4rs and race bikes ... and they also have an oil cooler right?

(added) SO ... as heman points out below  ....more valves = more power = more heat = more cooling requirement (seems simple enough; but I know theres gotta be more technical details to it than that)

[ducpainter]

I'll reiterate from the other thread...

To the best of my knowledge the early 900s were the only air/oil cooled engines. It actually used an oil jacket around the cylinders to assist in cooling the cylinders.

An oil cooler does not mean the engine is oil cooled. It simply means the oil is cooled.

[Juan]

I'll reiterate from the other thread...

To the best of my knowledge the early 900s were the only air/oil cooled engines. It actually used an oil jacket around the cylinders to assist in cooling the cylinders.

An oil cooler does not mean the engine is oil cooled. It simply means the oil is cooled.

+ 1 and because the oil is cooled by air they are still called air cool.
Maybe Stu can give us some more light into this..! 

[Bill in OKC]

If I understand the original question correctly, the reason for the progression from air to oil to water relates more to the state of tune than the engine size or number of valves.  I don't know what the biggest engine that can be air cooled is, but it is bigger than most motorcycle engines.  Older VWs were air cooled, the larger Porsches were air/oil cooled and now they are water cooled.  Suzuki GSXRs went from oil to water cooling when the heat output of their engines exceeded the oil cooling's capability.  Suzuki's engines had to make more and more power to keep up with the competition and they just needed more cooling to run reliably at the level of tune.

[He Man]

More power = more heat.

999cc 2v = less power less heat, than a 999cc 4v

4v burns more air and fuel per a cycle than a 2v hence more power more heat.

[herm]

If I understand the original question correctly, the reason for the progression from air to oil to water relates more to the state of tune than the engine size or number of valves.  I don't know what the biggest engine that can be air cooled is, but it is bigger than most motorcycle engines.  Older VWs were air cooled, the larger Porsches were air/oil cooled and now they are water cooled.  Suzuki GSXRs went from oil to water cooling when the heat output of their engines exceeded the oil cooling's capability.  Suzuki's engines had to make more and more power to keep up with the competition and they just needed more cooling to run reliably at the level of tune.

biggest i am aware of...

[DuciD03]

so.  After reading through all this.  Water cooled vs. Air cooled in the traditional sense would be antifreeze/water vs. Just Oil.  I get that.  I am thinking an oil cooler is not necessarily what makes a bike oil cooled.  Is it jackets and channels in the motor to allow the oil to cool the engine that make it oil cooled.  These sound like places the oil is doing something other than lubricating. 

A straight up explanation would be great.

On a side note.  up until 1996 the Porsche 911 was air cooled.  Least that is what people said, I believe in actuality it was oil cooled as it took 9 quarts of oil and had an oil cooler up front where you would find a radiator on normal cars. 

I assume my s2r1000 is oil cooled. 

from other thread ...

[He Man]

If your asking why they use water over oil for cooling. I think the answer is in heat absorbtion.


Water's specific heat capcity is 4.16 kJ/kg K. That is it takes 4160 joules of energy to heat 1 kg of water 1 kelven.
4160 joules of energy.

I looked it up, and most oils are around 2kj/kgK.

[Speeddog]

Well, this engine is pretty big, Pratt & Whitney 4360:

[Speeddog]

Big advantages to water over oil for cooling; thermal conductivity is good and specific heat is good.

In simple terms, it can pull heat out of the engine quickly, and can store a lot of heat per pound.
So it can be a smaller and lighter cooling system if you use water instead of oil.

Advantage of oil cooling, you don't have an extra 'system', and you can put oil where you can't put water.
For example, many Duc engines spray oil on the bottom of the piston.

[Bizzarrini]

Perhaps another variable in the equation is the location of the engine? I can imagine that air cooling is a bit difficult if it's fully enclosed in bodywork, even if the displacement or the state of tune is relatively low? Interesting topic though!

[Scissors]

In an ultimate sense, true cooling of the engine itself is achieved through convection and radiation.

Convection carries heat away by transferring it to the air.  Most of the heat lost through air is actually the air coming from the exhaust; most of the rest is shed via the air which moves through the fins found on radiators and engines themselves.

Heat is also lost in the form of radiation, primarily infrared but also long-wavelength visible light in extremely hot components such as an exhaust header at WOT near redline.

Some of the geeks may be thinking "what about conduction?"  But conduction, for the most part, does not take heat from the engine except where the engine touches other components such as the frame which carry the heat away.  What conduction does do is move heat to another area, such as an engine cooling fin or coolant which will be circulated through a radiator, where the heat will actually be shed through convection and radiation.

Ultimately, all motorcycle engines are "air-cooled" but reasonable people understand that the term "air-cooled" specifically refers to engines which shed heat without the assistance of a dedicated liquid circuit.  Is there a limit to engine size due to air-cooling?  Not at all.

What water cooling allows is much more precise control over the temperature of the engine through the use of the thermostat (a valve which determines the engine's minimum running temperature) and a cooling fan (which determines the engine's maximum running temperature).  You can't very well just shut off the supply of oil, now can you?  This precise control results in one less variable and thus makes it easier to design an engine with far tighter tolerances; it also allows you to keep an engine at a temperature which is superior for power and emissions.

On an air-cooled engine, the best you can do is use a fan on an oil cooler to provide a maximum operating temp, but there's no real control to prevent the temperature from dropping too far.

[DuciD03]

 ooow; yes, yes, yes ...

yyyyyooooouuu guyyyyyyyyyys .... are good!  ......... told ya theres more to it! I knew it.

keep it comming; ita a multifacited question ...

[scott_araujo]

Also, water cooling allows you to maintain a very specific operating temperature.  The operating temperature of air cooled engines vary widely because you can only put so much control over the air flow around the engine and the ambient temperature.  A thermostat in a radiator can open and close to keep the temperature right where you want it.  The significant advantage here is that since the engine has a limited operating temperature range you can make then tolerances on everything in the engine tighter.  This means more efficiency, more power.  Air cooled engines have to be looser for the larger temperature ranges they operate in.

Airplane engines are great candidates for air cooling.  There's always plenty of cool air around and then tend to run at set speeds rather than throttling up and down like land vehicles.  It also removes the water cooling system, just another system that could fail.  They are no doubt among the largest and most powerful air cooled engines.

For more traditional land based vehicles, the twin turbo Porsches that ran at Le Mans through the late 60s and early 70s (I think) were staggeringly powerful.

Scott

[Keld]

Airplane engines are great candidates for air cooling.  There's always plenty of cool air around and then tend to run at set speeds rather than throttling up and down like land vehicles.  It also removes the water cooling system, just another system that could fail.  They are no doubt among the largest and most powerful air cooled engines.

You also save some weight, a good thing when airborne