beehive specific question
11-09-06, 07:47 PM
#26
Jeff, I didn't mention the valve at the heater core, took that as a given that we all knew about it. I know, I should never assume, lol.
Since I can't seem to figure in my head a way around the flow pattern, pressure differentials, Bernouli effect, etc., let me throw out another option.
A Holley kit I bought on eBay a few years ago came with an electric water pump motor and belt. This didn't replace the pump, it simply spun it instead of using the main pulley. If one were to install this type of motor to spin a remote mount fluid pump, you could tap the top and bottom of the radiator and bypass the engine block entirely. With some creative electronics, the pump speed could be varied with engine rpm or temperature of the oil.
I realise this isn't as simple a solution as changing the orifice, it's more like building the space shuttle to go to the grocery store, but it may have enough merit to consider.
Since I can't seem to figure in my head a way around the flow pattern, pressure differentials, Bernouli effect, etc., let me throw out another option.
A Holley kit I bought on eBay a few years ago came with an electric water pump motor and belt. This didn't replace the pump, it simply spun it instead of using the main pulley. If one were to install this type of motor to spin a remote mount fluid pump, you could tap the top and bottom of the radiator and bypass the engine block entirely. With some creative electronics, the pump speed could be varied with engine rpm or temperature of the oil.
I realise this isn't as simple a solution as changing the orifice, it's more like building the space shuttle to go to the grocery store, but it may have enough merit to consider.
11-10-06, 02:10 AM
#27
Lives on the Forum
When Jeff asks a question, you can be sure it will be a good one! 
Going back to the whole theory that you have to slow down the flow to allow the water to "pick up" the heat, well this still doesn't make sense to me. If you place a warm bottle of anything into a cold stream, it will cool down faster in a fast flowing stream than in a cold one. Basically, the water flow isn't "picking up heat" so much as it is cooling the metal of the beehive. A fast flow will cool that better than a slow one, I'm sure. Anybody know what I mean?
Going back to the whole theory that you have to slow down the flow to allow the water to "pick up" the heat, well this still doesn't make sense to me. If you place a warm bottle of anything into a cold stream, it will cool down faster in a fast flowing stream than in a cold one. Basically, the water flow isn't "picking up heat" so much as it is cooling the metal of the beehive. A fast flow will cool that better than a slow one, I'm sure. Anybody know what I mean?
11-10-06, 10:44 AM
#28
400WHP or bust
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Yeah thats because it's in a open environment with more volume of the cooler substance the heat will disipate into the stream, the cooling system is a closed system, and the temp is basically consistant and the surrounding environment is warmer than the coolant, which is why the coolant is taking the heat out of it.. The retriction with also create a pressure differental and will create a "vacuum" to move the coolant faster, like the venturi in a carburator.
At least that is what we were taught in college advanced Hydraulic systems, I'll look more into it.
At least that is what we were taught in college advanced Hydraulic systems, I'll look more into it.
11-10-06, 12:41 PM
#29
So it seems the jury is still out on the usefulness of the restrictor. Thank you everyone for your intput.
I don't want his thread to go away too quickly; it'll drop to the 2nd page within a day without new posts, but I don't really have any more to add. I want others to see it and maybe attempt some experiements with and without the restrictor on their own. I intend to do it myslf, but it may be a little while as I still have about a gazillion projects ahead of it.
It looks like I've reached the limit in my understanding of how and where everything is going to fit in the project (baja bug) without having physically installed the engine yet. I'm sure once the engine is in there, the location of the radiator and exhaust will come to me much like they did with the GLC 20B project, GSL-SE 4 rotor project, my friend's 13B baja bug et al. Yes, I have actually been designing everything about my baja project in my head, but I can only keep track of so many things at once. It sucks too because it's currently on my mind and will have to be put on the back burner in order to finish several other projects before I can get back to it. I'd better get to work instead of spending all this time on the forum.
Please feel free to keep adding to this thread with your thoughts and theories. I'll add to it when I can.
I don't want his thread to go away too quickly; it'll drop to the 2nd page within a day without new posts, but I don't really have any more to add. I want others to see it and maybe attempt some experiements with and without the restrictor on their own. I intend to do it myslf, but it may be a little while as I still have about a gazillion projects ahead of it.
It looks like I've reached the limit in my understanding of how and where everything is going to fit in the project (baja bug) without having physically installed the engine yet. I'm sure once the engine is in there, the location of the radiator and exhaust will come to me much like they did with the GLC 20B project, GSL-SE 4 rotor project, my friend's 13B baja bug et al. Yes, I have actually been designing everything about my baja project in my head, but I can only keep track of so many things at once. It sucks too because it's currently on my mind and will have to be put on the back burner in order to finish several other projects before I can get back to it. I'd better get to work instead of spending all this time on the forum.
Please feel free to keep adding to this thread with your thoughts and theories. I'll add to it when I can.
05-20-07, 08:05 PM
#30
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Any updates on this? I'm now very interested in adding a beehive rather than a fmoc, on my new 4port 13b project, just because I dont feel like buying a fmoc and dealing w/ everything needed to hook it up (fittings,hoses,etc.) Also the 12a plate already has everything needed to just hook right up. Any advice?
05-20-07, 08:32 PM
#32
I have some updates. I quite recently rebuilt a 12A and installed a beehive. The heater core tube on the car didn't have a restrictor in it. Quite interesting.
Guess how hot it gets? I have no idea lol but the temp guage stays comfortably low, and it's a fresh rebuild, which tend to run hotter than fully broken in engines. Looks like the beehive is functioning perfectly.
Some more news. My friend's baja does great with a 13B and a beehive with the radiator in the back. It's a huge aluminum one, basically overkill, but that's a good idea in a baja. It never overheats.
+2 for the beehive and no restrictor.
Guess how hot it gets? I have no idea lol but the temp guage stays comfortably low, and it's a fresh rebuild, which tend to run hotter than fully broken in engines. Looks like the beehive is functioning perfectly.
Some more news. My friend's baja does great with a 13B and a beehive with the radiator in the back. It's a huge aluminum one, basically overkill, but that's a good idea in a baja. It never overheats.
+2 for the beehive and no restrictor.
05-21-07, 10:46 AM
#34
No. Imagine a standard Mazda heater core pipe. You know aproximately how large it is just looking at it. Now imagine a washer brazed onto the end that heads over to the top coolant fitting on the beehive. This washer (restrictor) is located under the firewall fitting. There is a T fitting there. The vertical one goes up into the heater core. The horizontal one has the restrictor and heads over to the beehive.
I think the hole is just large enough to pass a normal 8mm x 1.25 bolt threaded section. That's the common size with the 12mm head you find all over the engine. You know those two raised threaded holes on top of the rotor housings and the flat slanted surface on the intermediate plate? That's the hole size in the restrictor.
I think the hole is just large enough to pass a normal 8mm x 1.25 bolt threaded section. That's the common size with the 12mm head you find all over the engine. You know those two raised threaded holes on top of the rotor housings and the flat slanted surface on the intermediate plate? That's the hole size in the restrictor.
05-21-07, 08:01 PM
#35
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Cool I'm gonna go take a look now. I met a guy who ran 13b w/nos and NO oil cooler. Ran under 11 sec. I asked him why and he stated that for 1/4 mile racing its not needed. Hmmm, my thing is I dont really race and I only drive my baby on the weekends for about 20 min tops! I think the beehive w/no restrictor will work for my driving.
03-31-09, 01:37 PM
#38
Comment to Nismo Convert 86.
Higher flowrate of water over the heat transfer surface will result in more heat transferred from the oil (assuming of course that the water is colder than the oil). The higher flowrate results in a higher surface heat transfer coefficient on the water side of the exchanger. The increase in the water temperature will be less, but the total heat removed will be greater because of the higher flowrate. This is a basic engineering fact.
Your understanding that the heat transfer medium "needs time" to transfer the heat is a common misconception. In my line of work (designing steam generators), I have demonstrated to doubting power plant operators over the last +30 years that this is true.
Without looking at the Mazda system more closely, I really can't say why they put a restriction orifice in the line, but I think that the comments considering balancing heat removal/distribution through the entire system are most likely correct. Economy always plays some role as well.
Carl
Higher flowrate of water over the heat transfer surface will result in more heat transferred from the oil (assuming of course that the water is colder than the oil). The higher flowrate results in a higher surface heat transfer coefficient on the water side of the exchanger. The increase in the water temperature will be less, but the total heat removed will be greater because of the higher flowrate. This is a basic engineering fact.
Your understanding that the heat transfer medium "needs time" to transfer the heat is a common misconception. In my line of work (designing steam generators), I have demonstrated to doubting power plant operators over the last +30 years that this is true.
Without looking at the Mazda system more closely, I really can't say why they put a restriction orifice in the line, but I think that the comments considering balancing heat removal/distribution through the entire system are most likely correct. Economy always plays some role as well.
Carl
03-31-09, 04:56 PM
#40
I totally agree with Carl.
A quick test anybody can do to prove that he's correct is to take two identical metal objects (a pair of spoons for instance) heat them up in a pot of hot or boiling water (whichever you're comfortable with and won't burn yourself much). Then fill two large cups with cold water. Dunk both spoons in the cold water taking care to swish one around while holding the other stationary, you know, to give the water "more time" to absorb the heat. Do this for hmm let's say 2 seconds. Pull them both out and check the temperature of both. I'll bet dollars to doughnuts the spoon you swished around will be a lot cooler than the other you just let sit there. Why do you s'pose that is? Carl answered it.
A quick test anybody can do to prove that he's correct is to take two identical metal objects (a pair of spoons for instance) heat them up in a pot of hot or boiling water (whichever you're comfortable with and won't burn yourself much). Then fill two large cups with cold water. Dunk both spoons in the cold water taking care to swish one around while holding the other stationary, you know, to give the water "more time" to absorb the heat. Do this for hmm let's say 2 seconds. Pull them both out and check the temperature of both. I'll bet dollars to doughnuts the spoon you swished around will be a lot cooler than the other you just let sit there. Why do you s'pose that is? Carl answered it.
04-01-09, 04:51 PM
#41
Jeff, while your arguement appears sound at first, there is a flaw in it. One spoon is transfering heat through a static environment, the other through a dynamic environment. The static one builds up stratified layers of increasingly hotter water around it, with the coolest water contacting the surface. The dynamic one is constantly exposed to the hottest water. Think of it as how wind chill works and how heat stratifies in layers in your house during the winter.
I went out to the shop and looked at the only 7 that still has the stock beehive setup. That, along with looking at the coolant flow diagram in the FSM and Rogue Woulf's comment that the flow from the heater goes back to the lower radiator line leads me to one supposition and one food for thought. I still believe the restrictor directs more coolant through the heater core, the supposition.
The food for thought is, since where the beehive is located, the restrictor may limit the total amount of coolant pulled back through to the lower hose so it can instead continue it's path forward on the passenger side of the engine to the radiator.
If that's the case, that may account for why there is a bypass in the waterpump housing. Another reason for the bypass may simply be to prevent cavitation around the waterpump impellers, which most boaters know wears out props faster than staying immersed in water does.
I went out to the shop and looked at the only 7 that still has the stock beehive setup. That, along with looking at the coolant flow diagram in the FSM and Rogue Woulf's comment that the flow from the heater goes back to the lower radiator line leads me to one supposition and one food for thought. I still believe the restrictor directs more coolant through the heater core, the supposition.
The food for thought is, since where the beehive is located, the restrictor may limit the total amount of coolant pulled back through to the lower hose so it can instead continue it's path forward on the passenger side of the engine to the radiator.
If that's the case, that may account for why there is a bypass in the waterpump housing. Another reason for the bypass may simply be to prevent cavitation around the waterpump impellers, which most boaters know wears out props faster than staying immersed in water does.
04-01-09, 09:42 PM
#43
Trochoid, you explained perfectly why higher velocity improves heat transfer. Is that what you had in mind? The dynamic condition (more dynamic as velocity increases) is what improves the heat transfer.
Lascelles, heat transfer is not more efficient at laminar flow for the same reason Trochoid stated above. Laminar flow is kind of like the static that he describes. I have attached a pretty clear text book explanation of the phenomenon. It is the same that I sent to a power plant engineer a few months ago to help explain some observations he had made.
Carl
Lascelles, heat transfer is not more efficient at laminar flow for the same reason Trochoid stated above. Laminar flow is kind of like the static that he describes. I have attached a pretty clear text book explanation of the phenomenon. It is the same that I sent to a power plant engineer a few months ago to help explain some observations he had made.
Carl
04-02-09, 03:10 AM
#44
Carl, while I understand a small part of those 4 pages, most of it's way over my head. I've had 1 course in fluid dynamics and 1 in statics for my degree. To me, the above pages look to be Masters or PHD course work. You must have a very interesting and challenging job.
I've had 1 course in fluid dynamics and 1 in statics for my degree. To me, the above pages look to be Masters or PHD course work. You must have a very interesting and challenging job.
04-02-09, 09:32 AM
#45
I wasn't trying to be a smart *** or anything. Just trying to give an explanation that had some substance to it (ie something other than opinion).
There is a lot of engineering jargon that can be confusing in the pages I included. Here is a distillation using the author's own words.
"In laminar flow through a duct, just as for laminar flow over a plate, there is no mixing of warmer and colder fluid particles by eddy motion and the heat transfer takes place solely by conduction. Since all fluids ..... have small thermal conductivities, the heat transfer coefficients in laminar flow are relatively small. In transitional flow (ed. higher velocity) a certain amount of mixing occurs by means of eddies which carry warmer fluid into cooler regions, and vice versa. Since the mixing motion, even it if is only on a small scale, accelerates the transfer of heat considerably, a marked increase in the heat transfer coefficient occurs....(at least one page later)...An increase of the flow velocity yields higher heat transfer coefficients.......Whenever possible, laminar flow is avoided in heat exchange equipment because of the low heat transfer coefficients obtained." Kreith "Principles of Heat Transfer". The textbook is actually for an undergraduate mechanical or chemical engineering course.
There are also some comments about compromises for economic design, something that I am sure the Mazda engineers had to take into consideration.
I hope this helps the general understanding of beehive (or air-cooled) oil coolers. It is of course a bit off the original track of why the restrictor is in the water line. When I get my race car back off the trailer (in storage) to do some exhaust mods, I will have to look more closely at the water and oil routing of the beehive cooler. I have a 2nd gen air cooler, I have been thinking of putting on the car. This whole discussion might speed up the conversion.
Carl
There is a lot of engineering jargon that can be confusing in the pages I included. Here is a distillation using the author's own words.
"In laminar flow through a duct, just as for laminar flow over a plate, there is no mixing of warmer and colder fluid particles by eddy motion and the heat transfer takes place solely by conduction. Since all fluids ..... have small thermal conductivities, the heat transfer coefficients in laminar flow are relatively small. In transitional flow (ed. higher velocity) a certain amount of mixing occurs by means of eddies which carry warmer fluid into cooler regions, and vice versa. Since the mixing motion, even it if is only on a small scale, accelerates the transfer of heat considerably, a marked increase in the heat transfer coefficient occurs....(at least one page later)...An increase of the flow velocity yields higher heat transfer coefficients.......Whenever possible, laminar flow is avoided in heat exchange equipment because of the low heat transfer coefficients obtained." Kreith "Principles of Heat Transfer". The textbook is actually for an undergraduate mechanical or chemical engineering course.
There are also some comments about compromises for economic design, something that I am sure the Mazda engineers had to take into consideration.
I hope this helps the general understanding of beehive (or air-cooled) oil coolers. It is of course a bit off the original track of why the restrictor is in the water line. When I get my race car back off the trailer (in storage) to do some exhaust mods, I will have to look more closely at the water and oil routing of the beehive cooler. I have a 2nd gen air cooler, I have been thinking of putting on the car. This whole discussion might speed up the conversion.
Carl
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