Theory ... water flow
01-10-2007, 11:04 AM
#31
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Re: Theory ... water flow
I've run 525SC without bypass or thermostat. Water temps were generally 120-140. Oil got up in the low 200s.
When I tried this on a lower hp engine, my oil temp never got over 180 degrees= condensation = bad, mkay?
I switched over to a bypass and tried 140, 160, and 180 degree thermostats.
Like Goldilocks said. 140, the oil was too cold, 180 the oil was too hot, 160, it was just right.
Monitor your block and oil temps. Use a crossover and thermostat if needed.
Gary
When I tried this on a lower hp engine, my oil temp never got over 180 degrees= condensation = bad, mkay?
I switched over to a bypass and tried 140, 160, and 180 degree thermostats.
Like Goldilocks said. 140, the oil was too cold, 180 the oil was too hot, 160, it was just right.
Monitor your block and oil temps. Use a crossover and thermostat if needed.
Gary
01-10-2007, 02:34 PM
#32
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Re: Theory ... water flow
Never ran thermostats in that boat when I had it. Water temps were always about 135 and oil temps were 225.
My current boat doesn't have them either...but it does run a litter colder on the water temp (110-115) and about the same on oil temps.
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Happily retired and living in Heavens waiting room.
01-10-2007, 02:47 PM
#33
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Re: Theory ... water flow
How about, it doesnt make that much difference. Lots of motors have stats, lots dont and they all seem to work fine. Lots of physics review needed here....Wow.
01-10-2007, 06:36 PM
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Re: Theory ... water flow
not a lot of review necessary at all. the physics thermodynamics aspect of this discussion are crystal clear and as simple as it gets.
the ability of one medium to cool ( or heat) another is strictly a function of three elements:
the specific heat of the two compnents
the surface area exposed and in intimate contact
the elapsed time time the surfaces are in contact.
all the rest are constants and nothing else matters.
in the case you guys are arguing ( excuse me, DISCUSSING) all that is really in question is the efficiency that you want to cool at. in the first extreme case where you have zero water pressure and water moving at an EXTREMELY high speed thru the system, it is an entirely possible scenario that each unit volume of water does not spend enough time in intimate contact with the block to sucessfully raise its temperature ( take heat AWAY from the block) before it moves on ... in a sense, your block GENERATES move btus then you can get rid of with the coolant.
in the other extreme, where you have something above the minimum pressure required to assure intimate contact but you move the water too slowly, the the delta T beomes zero, between the two components ( tyhe "coolant" becomes heat saturated ) and you simply create an equilibrium that is higher than you want... right up until the water boils and thats that. remembering of course that the boiling point is raised by the pressure in what is essentially a linear fashion.
so....
the physics and thermodynamics are clear and undeniable. the only real questions are :
what do you really want for operating temperature
versus
how are you going to get rid of the heat youre putting in at the CORRECT rate to create that equilibrium.
the hardware aspect of that answer is whatever you care to make of it.
you want to run no tsat because god told you in your sleep that they are evil ? fine... build enough pressure to ensure intimate contact and slow the water flow down to whatever the rate necessary is to allow the water to heat and therefore tranfer the heat out of the engine. thats what restrictor plates do.
want to operate the boat at a wide variety of speeds and conditions while maintaining the necessary and desireable operating temps as defined by the metallurgy of the components youve selected for internals and clearences ? use a tsat with a sufficient flow rate at wide open to assure your max operating parameters are covered.
i have made known my opinion about running these motors or ANY motors like this overcooled... i think you guys that do that are simply giving up performance and wearing out your motors for no reason what so ever... and im not talking about the 40 psi blower motors you guys tinker with with all the bizzare combinations that you can think of... im talking about your basic normally aspirated big block with a carb and intelligent compression ratio...
my solution has always been.... define the water cooling to make the water temps 180, make the oil cooling such that they are between 210 and 240 all the time including during the most extreme sustained conditions. don't try to make one system do the job of the other.
its nothing i invented. its a concept proven correct by essentially every single manufacturer of internal combustion engines on the planet and just happens ( by shear luck i suppose, ) to be supported by the simple principles as defined by the physics and thermodynamics as they are understood by the real world for the last 150 years or so.
the ability of one medium to cool ( or heat) another is strictly a function of three elements:
the specific heat of the two compnents
the surface area exposed and in intimate contact
the elapsed time time the surfaces are in contact.
all the rest are constants and nothing else matters.
in the case you guys are arguing ( excuse me, DISCUSSING) all that is really in question is the efficiency that you want to cool at. in the first extreme case where you have zero water pressure and water moving at an EXTREMELY high speed thru the system, it is an entirely possible scenario that each unit volume of water does not spend enough time in intimate contact with the block to sucessfully raise its temperature ( take heat AWAY from the block) before it moves on ... in a sense, your block GENERATES move btus then you can get rid of with the coolant.
in the other extreme, where you have something above the minimum pressure required to assure intimate contact but you move the water too slowly, the the delta T beomes zero, between the two components ( tyhe "coolant" becomes heat saturated ) and you simply create an equilibrium that is higher than you want... right up until the water boils and thats that. remembering of course that the boiling point is raised by the pressure in what is essentially a linear fashion.
so....
the physics and thermodynamics are clear and undeniable. the only real questions are :
what do you really want for operating temperature
versus
how are you going to get rid of the heat youre putting in at the CORRECT rate to create that equilibrium.
the hardware aspect of that answer is whatever you care to make of it.
you want to run no tsat because god told you in your sleep that they are evil ? fine... build enough pressure to ensure intimate contact and slow the water flow down to whatever the rate necessary is to allow the water to heat and therefore tranfer the heat out of the engine. thats what restrictor plates do.
want to operate the boat at a wide variety of speeds and conditions while maintaining the necessary and desireable operating temps as defined by the metallurgy of the components youve selected for internals and clearences ? use a tsat with a sufficient flow rate at wide open to assure your max operating parameters are covered.
i have made known my opinion about running these motors or ANY motors like this overcooled... i think you guys that do that are simply giving up performance and wearing out your motors for no reason what so ever... and im not talking about the 40 psi blower motors you guys tinker with with all the bizzare combinations that you can think of... im talking about your basic normally aspirated big block with a carb and intelligent compression ratio...
my solution has always been.... define the water cooling to make the water temps 180, make the oil cooling such that they are between 210 and 240 all the time including during the most extreme sustained conditions. don't try to make one system do the job of the other.
its nothing i invented. its a concept proven correct by essentially every single manufacturer of internal combustion engines on the planet and just happens ( by shear luck i suppose, ) to be supported by the simple principles as defined by the physics and thermodynamics as they are understood by the real world for the last 150 years or so.
Last edited by stevesxm; 01-10-2007 at 06:42 PM.
01-11-2007, 12:58 AM
#36
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Re: Theory ... water flow
The theory stated above that the faster the water is moving the less time it has to pick up heat and therefore the motor will transfer less heat to the water is incorrect. The water temp goes down because the heat is transferred into a greater volume of water so the water temperature does not rise as much as when the flow is lower. If the motor is running at constant load or more specifically generating the same amount of heat over time, raising the velocity/flow of the water will INCREASE the heat transferred since the water is at a lower temperature. The bigger the temperature difference between the block/heads and the water the more heat will be transferred.
For example, if water is flowing at 15 lb/hr and you add 30 BTU of heat to the water in an hour, the water temp will raise 2 degrees since the heat capacity of water is 1 BTU/lb/deg F. If you raise the flow to 30 lb/hr and still transfer 30 BTU of heat to the water in an hour the water temperature will only rise 1 degree.
Any obersvations or problems observed to the contrary are due to other factors. I read an article where Reggie Fountain discussed keeping water pressure up to keep steam from forming in the heads which could occur in low flow areas. The point being that if you reduce flow restrictions in the motor to get more water flow the associated reduction in pressure would cause the problem since water boils at lower temperatures with decreasing pressure. But, more water flow will not in and of itself cause higher block/motor temps. The best situation for cooling problems would be to install a pump that would raise the pressure of the water. That way the increased pressure would cause increased flow, maintain pressure in the block/heads and all should be OK. However, with no pump like that readily available and raising the possibility of blowing intake gaskets with increased pressure the only option is to reduce the resistance to flow to get more water i.e. remove the tstat like I did on my modified 500 hps.
For example, if water is flowing at 15 lb/hr and you add 30 BTU of heat to the water in an hour, the water temp will raise 2 degrees since the heat capacity of water is 1 BTU/lb/deg F. If you raise the flow to 30 lb/hr and still transfer 30 BTU of heat to the water in an hour the water temperature will only rise 1 degree.
Any obersvations or problems observed to the contrary are due to other factors. I read an article where Reggie Fountain discussed keeping water pressure up to keep steam from forming in the heads which could occur in low flow areas. The point being that if you reduce flow restrictions in the motor to get more water flow the associated reduction in pressure would cause the problem since water boils at lower temperatures with decreasing pressure. But, more water flow will not in and of itself cause higher block/motor temps. The best situation for cooling problems would be to install a pump that would raise the pressure of the water. That way the increased pressure would cause increased flow, maintain pressure in the block/heads and all should be OK. However, with no pump like that readily available and raising the possibility of blowing intake gaskets with increased pressure the only option is to reduce the resistance to flow to get more water i.e. remove the tstat like I did on my modified 500 hps.
01-11-2007, 12:28 PM
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Re: Theory ... water flow
with all due respect, moving the water too quickly is not a theory. it is fact.
pick up a physics book and read it. heat transfer is a strict function of time. in a closed loop system , the limiting factor becomes the heat exchanger unit... water to air. in a total loss system the limiting factor is flow rate and that and that alone controls the thermal equilibrium. if each unit volume transfers only a small amount because the flow rate is too high, you are required to run an EXTREMELY high flow rate to compensate... the total heat in HAS to equal the total heat out.... if you use only 1 % of the thermal transfer capacity of the coolant per cc because you never give it a chance to transfer then you need 100 times the flow rate to compensate... which mean pumping and friction losses and alll SORTS stupidity that is avoided simply by doing it right the first time. can you make it WORK ??? sure by why in gods name would you ?
in the case of steam pockets its the same thing. his OBSERVATION is correct but his analysis is flawed. you run pressure to keep the water in intimate contact AND to raise the boiling point . IF you do these two things then no steam pockets are possible. THAT critical pressure is a function of the hardware scheme and is NOT a one size fits all answer. steam pockets are the RESULT of failing to do either... NOT the REASON you do. the REASON you do it is because it is the CORRECT way to make a cooling system. like ANY system, if you design it correctly according to the science as opposed to voodoo and folklore, you don't HAVE mysterious problems to solve.... because they don't happen in the first place.
pick up a physics book and read it. heat transfer is a strict function of time. in a closed loop system , the limiting factor becomes the heat exchanger unit... water to air. in a total loss system the limiting factor is flow rate and that and that alone controls the thermal equilibrium. if each unit volume transfers only a small amount because the flow rate is too high, you are required to run an EXTREMELY high flow rate to compensate... the total heat in HAS to equal the total heat out.... if you use only 1 % of the thermal transfer capacity of the coolant per cc because you never give it a chance to transfer then you need 100 times the flow rate to compensate... which mean pumping and friction losses and alll SORTS stupidity that is avoided simply by doing it right the first time. can you make it WORK ??? sure by why in gods name would you ?
in the case of steam pockets its the same thing. his OBSERVATION is correct but his analysis is flawed. you run pressure to keep the water in intimate contact AND to raise the boiling point . IF you do these two things then no steam pockets are possible. THAT critical pressure is a function of the hardware scheme and is NOT a one size fits all answer. steam pockets are the RESULT of failing to do either... NOT the REASON you do. the REASON you do it is because it is the CORRECT way to make a cooling system. like ANY system, if you design it correctly according to the science as opposed to voodoo and folklore, you don't HAVE mysterious problems to solve.... because they don't happen in the first place.
01-11-2007, 01:52 PM
#38
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Re: Theory ... water flow
with all due respect, moving the water too quickly is not a theory. it is fact.
pick up a physics book and read it. heat transfer is a strict function of time. in a closed loop system , the limiting factor becomes the heat exchanger unit... water to air. in a total loss system the limiting factor is flow rate and that and that alone controls the thermal equilibrium. if each unit volume transfers only a small amount because the flow rate is too high, you are required to run an EXTREMELY high flow rate to compensate... the total heat in HAS to equal the total heat out.... if you use only 1 % of the thermal transfer capacity of the coolant per cc because you never give it a chance to transfer then you need 100 times the flow rate to compensate... which mean pumping and friction losses and alll SORTS stupidity that is avoided simply by doing it right the first time. can you make it WORK ??? sure by why in gods name would you ?
in the case of steam pockets its the same thing. his OBSERVATION is correct but his analysis is flawed. you run pressure to keep the water in intimate contact AND to raise the boiling point . IF you do these two things then no steam pockets are possible. THAT critical pressure is a function of the hardware scheme and is NOT a one size fits all answer. steam pockets are the RESULT of failing to do either... NOT the REASON you do. the REASON you do it is because it is the CORRECT way to make a cooling system. like ANY system, if you design it correctly according to the science as opposed to voodoo and folklore, you don't HAVE mysterious problems to solve.... because they don't happen in the first place.
pick up a physics book and read it. heat transfer is a strict function of time. in a closed loop system , the limiting factor becomes the heat exchanger unit... water to air. in a total loss system the limiting factor is flow rate and that and that alone controls the thermal equilibrium. if each unit volume transfers only a small amount because the flow rate is too high, you are required to run an EXTREMELY high flow rate to compensate... the total heat in HAS to equal the total heat out.... if you use only 1 % of the thermal transfer capacity of the coolant per cc because you never give it a chance to transfer then you need 100 times the flow rate to compensate... which mean pumping and friction losses and alll SORTS stupidity that is avoided simply by doing it right the first time. can you make it WORK ??? sure by why in gods name would you ?
in the case of steam pockets its the same thing. his OBSERVATION is correct but his analysis is flawed. you run pressure to keep the water in intimate contact AND to raise the boiling point . IF you do these two things then no steam pockets are possible. THAT critical pressure is a function of the hardware scheme and is NOT a one size fits all answer. steam pockets are the RESULT of failing to do either... NOT the REASON you do. the REASON you do it is because it is the CORRECT way to make a cooling system. like ANY system, if you design it correctly according to the science as opposed to voodoo and folklore, you don't HAVE mysterious problems to solve.... because they don't happen in the first place.
01-11-2007, 07:10 PM
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Re: Theory ... water flow
Steve, If the water does not stay in contact with the block long enough what is the "too fast" water replaced with? It is replaced with cold water if the flow rate is high. What does the new water do, pickls up heat. Right you are though, keep block pressure between 15 and 20 with sufficient flow and all will be well.
Make sure plenty of water is able to exit the exhaust, high flow t-stat and dump the excess pressure off after the oil cooler.
Make sure plenty of water is able to exit the exhaust, high flow t-stat and dump the excess pressure off after the oil cooler.
01-11-2007, 07:13 PM
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Re: Theory ... water flow
also the idea of stats on a high perf engine is not a good one.
many of the conflicting posts, and book theories, and " i read this in hot boat" and the rest of it, is all nonsense. theory is not reality. and until you have been there and done that you should not make a decision for someone else.
i stand as stated ,,,,,,,,,,,, no stat.
has little to do with oil temps and milk shake. thats what the oil cooler and stat take care of.
why is it no auto's have oil temp gauges.
you are talking about an engine which is designed to run at high rpm's for an extended amount of time.not idlinmg in traffic or shifting.
heat transfer, molecules, intimate contact.
horse poo, none of that truly has a dramatic effect at 5500 / 6000 rpm when you have it bricked for an hour on a poker run. do you really think your gonaa remove all the little tiny air bubbles,,,,,,,,,,,,,,,,,,,,,,no..
stock being too critical, aand go blow your stuff up.
lol, good luck
