Liquid Cooling

Discussion in '2-Stroke Engines' started by shell shock, Mar 3, 2012.

  1. shell shock

    shell shock Member

    I am thinking of making a Heat dissipation system for my china girl. Using copper tubes and some sort of coolant to be able to run my bike for long distance (100+ km). Im thinking of using one of my spare cylinder heads as a coiling the copper tubing around the aluminum. Using the principle of hot liquid rises i can make a simple induction system to cycle coolant through my cylinder.

    What do you think. And would this be something you would want a constant update follow through posted on?

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  2. blue 48

    blue 48 Member

    why???? ive done a 200km trip on mine only to stop and refuel and it never over heats dont over complicate these engines i believe.

    any way if you decide to do it keep us posted.
  3. shell shock

    shell shock Member

    Why? Because its cool! I know these engines can do way longer trips, but its just to say, hey look what i did! XP

  4. MikeJ

    MikeJ Member

    Leave the copper tubing off. There is not enough thermal conductivity between the cylinder and the tubing to be of any help. In fact, the tubing will hinder cooling of the cylinder by blocking air flow. ALL liquid cooled engines have the coolant in direct contact with the cylinder sleeve. All but the smallest ones like a 3 HP John Deere single cylinder engine (weighs a couple hundred pounds, 600 rpm max, found only in exhibitions) have forced water flow through a pump. Is found in every auto and truck from a commercial manufacturer.
  5. shell shock

    shell shock Member

    hmm.. this might take more then i thought. This will be moved to my beater engine. I might have to take this to the college machine shop. Thanks for the heads up MikeJ
  6. HeadSmess

    HeadSmess Well-Known Member

    machining a head with some kind of resevoir, so as to heat one can, say, pump it through the handlebars or something for those dark winter nights, then yeah, worth thinking about...

    technical complexities of liquid cooling prevents its widespread application...else youd be seeing every chainsaw n brushcutter with a radiator :jester:

    buuuuut, if youre determined to be different...

    knock out the central fins until theres only the top n bottom, bend up some 3mm ali sheet, to a close fit, get someone to weld it together for you, along with the n out, top n bottom...

    use the heater cores from a car...or two...

    theres electric waterpumps to be had... not entirely necessary depending on radiator size and cylinder design. in fact, on small engines, any engines, too much water flow can be more detrimental than not enough!

    on an r/c boat, for instance, while you can squirt water through fast enough to leave the head lukewarm or colder, its best to throttle it back til its coming out just under boiling point for maximum performance/longevity... oil gets thick when cold. metal likes to sieze when cold, etc etc etc...

    the auto pressurised systems allow you to run the engine over 100 deg c without your coolant boiling. higher pressure, higher boiling point. higher engine temp = more efficiency

    or even use some kind of retro worked fuel pump that works on case pulses? plenty of options really... you dont need masses of flow.
    *suits mechanically inclined*
    Last edited: Mar 4, 2012
  7. shell shock

    shell shock Member

    HeadSmess, that was some great info! Though with every reply and every bit of research im doing seems to make this prodject harder and harder.

    Also, while reading through my texts it seems that copper has a higher degree of thermal conductivity by almost 50% which would lead me to believe that this idea isnt too far fetched.
  8. motorpsycho

    motorpsycho Active Member

    air cooled engines are designed to be air cooled. there's no need to add a water cooling system.
    air cooled engines have been around FOREVER, they work, why mess with a design that has been proven to work already?
    I understand the want to design something different, but in this case, there's no reason to and it wouldn't be of any benefit.
  9. ddesens

    ddesens Member

    I am a firm believer in the K.I.S.S. system. "keep it simple stupid". Liquid cooling would be cool though.
  10. shell shock

    shell shock Member

    Why? *speech music playing* Why not? If we did not have an urge to progress beyond reason what would be of great historical discoveries. I push past logic just because i can! sure these china girls work fine the way they are, but why let that stop us? If people were satisfied with the standard gears, what would have become of shift kits, or what of the speed carbs? its all for the "luls" i say, to see what can be done!
  11. MikeJ

    MikeJ Member

    Now, mind you, an air-cooled to water-cooled engine conversion has been done. Lycoming Corporation makes air-cooled aircraft engines up one side and down the other. But they do offer a water-cooled version. (Just search for water-cooled Lycoming engines.) One of their engines was used to power the Voyager aircraft to around the world record in 1986. The aircraft had both an air-cooled and water-cooled engine. Richard Rutan (can't post his common nickname here), the pilot most of the way, shut off the air-cooled engine to save fuel for the around-the-world flight. The Lycoming site tells of the modifications made to the air-cooled engine for the water-cooled.

    A pressurized cooling system allows the coolant temperature to exceed normal boiling point. A cold engine is very inefficient, as pointed out earlier. Race car engines run pretty hot to squeeze out the horsepower. Grandma's grocery getter? If the thermostat exceeds 180F, I'd be surprised.

    In thermodynamics, a theory is that the hotter you can run an engine (before the lubricant breaks down and bearings melt down), the more efficient the engine runs. A mercury-cooled engine running at 500F is a lot more efficient than what we have today in pressurized water-based cooled engines. (Somehow, running around with 200 pounds of mercury in your cooling system would not set well with the EPA folks.)

    If you pursue this engineering endeavor, keep us posted. I'm confident it can be done. If not too costly, you will have a whole new engine when you get finished.
  12. motorpsycho

    motorpsycho Active Member

    yes, i understand your point, but seriously, this would be a waste of time in my opinon.
    develop something to make these little engines make more power instead.
    develop a v-twin, develop a better shift kit, something that would be worth the effort.
    Yes, without ideas that sound crazy at forst, we wouldn't be where we are now, but liquid cooling won't help you at all with an engine that was originally designed to be air cooled.
    go back and look at the dirt bikes from the late 70's (2 stroke- air cooled monsters.) then fast forward to the mid 80's when they introduced liquid cooled 2 strokes. they were a whole different design, not just an air cooled engine modified to be liquid cooled.
    you need to have a cylinder with water (or liquid) jackets machined into it to cool the cylinder and piston, The head also has to have water jackets machined into it. you would need to have a thermostat to regulate the engine temp for optimum performance because an engine that's running too cold will not run efficiently and it will shorten it's life span. you need a way to regulate the coolant to stay at the same temp all the time once it gets warmed up for it to be effective (just like a car.). running coils around the head won't do anything to help cooling in my opinion. If anything, by removing the center fins on the head, you've just reduced the surface area of the heat sink (which are the fins) and your engine will run hotter even if you do have coils running on top of the head with coolant in them.
  13. motorpsycho

    motorpsycho Active Member

    an air craft engine is a whole different animal wheather it's air cooled or liquid cooled. they are designed to run in very cold air, and they also run on high octane airplane fuel, not 87 octane gasoline.

    in todays cars, they are made to run hot for less emissions, but do those hotter temps make them have better performance? NO.
    racecars are a far different animal, and i gurantee you that the run a coolant additive to help reduce the temp of the coolant because big horsepower engines make big heat.
  14. HeadSmess

    HeadSmess Well-Known Member

    a hotter engine is more efficient. simple thermodynamics.

    air entering engine is at a certain temperature, therefore density.

    expansion is proprtional to temperature.

    the hotter that air can become, the more it expands.

    more expansion in a sealed cylinder equals more pressure.

    more pressure (on a piston) equals more power.

    so a hotter engine makes more power, unless the oil film is breaking down in which case its about to blow up 3/4 way down the strip...

    higher temps also burn fuel better, releasing more power than an old smoker with 6:1 CR which just clumps lots of carbon together as ash and soot... a win win for efficiency AND emissions :D
  15. motorpsycho

    motorpsycho Active Member

    so what your saying is that an engine that is running at 350-400 degrees makes more power than an engine that's running at 200 degrees?
    if that's the case, why is the most commonly used thermostat for a daily driver rated at 195 degrees?
    why is the most commonly used thermostat in a race car rated at 160 degrees?
    race cars make a lot more power than daily drivers, but yet they use lower rated thermostats, bigger radiators and coolant additives to reduce heat.
    daily drivers need to run hot to stay efficent and to reduce emissions, but yet they don't make a ton of power. if hotter engines made more power, we'd see 400 horsepower mini-vans running around.
    yes, a hotter engine makes more power, but there is a point to where an engine is too hot and it will begin to lose power.
    Last edited: Mar 5, 2012
  16. cloud_2901

    cloud_2901 Member

    Didn't some russian bloke make his own watercooled cylinder on here?

    Just sayin.. If they can do it there..
  17. HeadSmess

    HeadSmess Well-Known Member

    your race car is under some serious load, doing some major work. there is a limit to what abuse oils can withstand without losing their properties. once exceeded, the engine is compromised, failure imminent.

    there is a limit to the abuse the metals can withstand. aluminium gets weaker as it gets hotter, and then is expected to somehow accelerate then stop over 200 times a second? and keep doing it for a few hours at times?

    they have to get rid of that heat somehow. an ideal engine would convert ALL heat produced from combustion into mechanical energy.

    the world doesnt work like that, so you have to accept that over half your energy is wasted in just noise and heat. that heat has to go somewhere.

    the race engine producing more power for longer needs to get rid of a lot more heat. its oil has to stay slippery for the whole race. its pistons need to hold together, its conrods need to hold together...

    but, if we had the materials capable of making an engine that could operate at , say, 2000 degrees... we dont. dammit. not cheap ones, anyway :p

    russians? russians are crazy :) i like russians. they do interesting stuff :)
  18. motorpsycho

    motorpsycho Active Member

    makes sense to me.