More cooling with less air (closing off the nose)
May 14, 2015, 12:42 PM
#31
I dont think it being after the stat is going to tell you anything useful compared to it being before. that is IMO.
I never look at my stock gauge now. if in the same location (before tstat) the stock gauge could maybe tell you if your aftermarket one is failing, or vice versa
I never look at my stock gauge now. if in the same location (before tstat) the stock gauge could maybe tell you if your aftermarket one is failing, or vice versa
May 14, 2015, 02:16 PM
#32
I added dual coolers (tape them off in the winter to keep temps high enough)
I installed them high enough that they peek over the FMIC so that way they still get direct airflow. About 2/3s of the cooler is exposed to direct airflow.
Actual race cars put their cooler completely above in the nose section so they get loads of direct flow.
The entry/exit points on the oil coolers are facing down. This causes the entire oil cooler to not fill up and reduces the heat rejection ability (big air bubble in the top of the oil cooler that is compressed depending on the oil pressure).
The oil coolers appear to be in series. Logic tells me that the first oil cooler will have a higher temperature differential between the temperature of the oil and the ambient air than the second one. The first oil cooler will be more efficient than the second as the oil is cooler by the time it gets to the second cooler. You would likely see a higher heat rejection by routing the oil coolers in parallel so they both have the higher heat differential to ambient air.
May 14, 2015, 03:54 PM
#33
The oil coolers appear to be in series. Logic tells me that the first oil cooler will have a higher temperature differential between the temperature of the oil and the ambient air than the second one. The first oil cooler will be more efficient than the second as the oil is cooler by the time it gets to the second cooler. You would likely see a higher heat rejection by routing the oil coolers in parallel so they both have the higher heat differential to ambient air.
May 15, 2015, 07:39 AM
#34
Yes and your theory of them facing down and not filling all the way is also incorrect.
Our evos are known for running ridiculously high oil pressures. (still need to get the ER oil pump gear).
Adding any pressure let alone over 100PSI will clear out all the air and force oil through the entire system. When the engine is shut off, yes oil wont fully fill the coolers, but once running, the pressure will fill them. Basic hydrodynamics.
So dont worry about any of that.
Our evos are known for running ridiculously high oil pressures. (still need to get the ER oil pump gear).
Adding any pressure let alone over 100PSI will clear out all the air and force oil through the entire system. When the engine is shut off, yes oil wont fully fill the coolers, but once running, the pressure will fill them. Basic hydrodynamics.
So dont worry about any of that.
May 15, 2015, 09:14 AM
#35
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I dont think it being after the stat is going to tell you anything useful compared to it being before. that is IMO.
I never look at my stock gauge now. if in the same location (before tstat) the stock gauge could maybe tell you if your aftermarket one is failing, or vice versa
I never look at my stock gauge now. if in the same location (before tstat) the stock gauge could maybe tell you if your aftermarket one is failing, or vice versa
Yes and your theory of them facing down and not filling all the way is also incorrect.
Our evos are known for running ridiculously high oil pressures. (still need to get the ER oil pump gear).
Adding any pressure let alone over 100PSI will clear out all the air and force oil through the entire system. When the engine is shut off, yes oil wont fully fill the coolers, but once running, the pressure will fill them. Basic hydrodynamics.
So dont worry about any of that.
Our evos are known for running ridiculously high oil pressures. (still need to get the ER oil pump gear).
Adding any pressure let alone over 100PSI will clear out all the air and force oil through the entire system. When the engine is shut off, yes oil wont fully fill the coolers, but once running, the pressure will fill them. Basic hydrodynamics.
So dont worry about any of that.
May 15, 2015, 09:45 AM
#36
^ what do you mean the oil will have more time in the cooler? there's fixed amount of fluid traveling through fixed volume. how can the oil stay in longer based on the rotation of the cooler. inlet and outlet is still at the same spot in relation to the cooler.
May 15, 2015, 02:16 PM
#37
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yeah nemo was only about 500whp. from most recent motoiq article:
imho it was an engine issue not cooling. the car actually had what i would consider a pretty large cooling opening in the front bumper as well as a lot of air extraction on the hood.
STM makes a modified oem thermostat housing that accepts a water temp sensor which i like better than putting an adapter in the middle of the hose. i think im gonna make an attempt at designing an "experiment" to get some data on this. my bumper is on a quick release so it wouldnt be difficult to change the amount of air blocking over the course of 1 track day so that the ambient conditions were as close as possible.
imho it was an engine issue not cooling. the car actually had what i would consider a pretty large cooling opening in the front bumper as well as a lot of air extraction on the hood.
STM makes a modified oem thermostat housing that accepts a water temp sensor which i like better than putting an adapter in the middle of the hose. i think im gonna make an attempt at designing an "experiment" to get some data on this. my bumper is on a quick release so it wouldnt be difficult to change the amount of air blocking over the course of 1 track day so that the ambient conditions were as close as possible.
All they do is weld an 1/8" npt bung onto the housing. Nothing a local welder couldn't do for anybody..
May 15, 2015, 03:18 PM
#38
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if the inlet/outlet are vertical (on the left side) and you have the oil enter at the bottom and have to fight the pressure gradient to get to the exit at the top, it will be in the cooler longer than if it enters at the top and just falls to the bottom thanks to physics.
May 15, 2015, 06:20 PM
#39
killer, its a closed system with constant pressure and the same volume. gravity will have no affect. (it probably has some impact but its not a real quantifiable amount and therefor a moot point) its going to push through what its going to push through at a given pressure regardless where the ports are and facing. the only time the force of gravity has any affect on that cooler is when the system is off.
May 15, 2015, 11:10 PM
#40
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Oil should always climb through a cooler, not fall through...
May 19, 2015, 01:34 PM
#41
Saying it's a closed system so it won't trap air is pretty crazy. The cooling system is also a closed system yet many overheating issues are due to trapped air. I wouldn't do it inlets down just for the fact they'll be above the pump and try to drain the cooler when you shut the car off. Now with air having to overcome the surface tension in the oil clearances to allow air in...probably not really an issue but I error on the side of caution with oil systems.
Series vs. Parallel, probably won't make a difference on cooling. It will make a difference in pressure drop though. The series setup will have 2X the internal flow speed, which off the top of me head I believe results in 4X the pressure loss?
It will create more turbulence that MIGHT improve heat transfer, but I kind of doubt it as the limiting factor of heat transfer likely isn't on the oil side but the air side. Then again, parallel might drop the flow speed low enough to create laminar flow which will have a big impact on pressure and heat transfer and isn't al all desirable. So in conclusion...yeah you'd need to do some actual calcs to figure it out.
Series vs. Parallel, probably won't make a difference on cooling. It will make a difference in pressure drop though. The series setup will have 2X the internal flow speed, which off the top of me head I believe results in 4X the pressure loss?
It will create more turbulence that MIGHT improve heat transfer, but I kind of doubt it as the limiting factor of heat transfer likely isn't on the oil side but the air side. Then again, parallel might drop the flow speed low enough to create laminar flow which will have a big impact on pressure and heat transfer and isn't al all desirable. So in conclusion...yeah you'd need to do some actual calcs to figure it out.
Last edited by 03whitegsr; May 19, 2015 at 01:37 PM.
May 20, 2015, 08:28 AM
#42
Series vs. Parallel, probably won't make a difference on cooling. It will make a difference in pressure drop though. The series setup will have 2X the internal flow speed, which off the top of me head I believe results in 4X the pressure loss?
It will create more turbulence that MIGHT improve heat transfer, but I kind of doubt it as the limiting factor of heat transfer likely isn't on the oil side but the air side. Then again, parallel might drop the flow speed low enough to create laminar flow which will have a big impact on pressure and heat transfer and isn't al all desirable. So in conclusion...yeah you'd need to do some actual calcs to figure it out.
It will create more turbulence that MIGHT improve heat transfer, but I kind of doubt it as the limiting factor of heat transfer likely isn't on the oil side but the air side. Then again, parallel might drop the flow speed low enough to create laminar flow which will have a big impact on pressure and heat transfer and isn't al all desirable. So in conclusion...yeah you'd need to do some actual calcs to figure it out.
Think of it like this:
If you an infinite number of small exchangers and you put them in series – then you will approach true counter flow service and the hot side outlet temp will equal the cold side inlet temp. A good examples is the feed/effluent exchangers in the NHT where the desire is to maximize heating of the feed and cooling of the reactor effluent.
If you have an infinite number of small exchangers and you put them in parallel – then the best you can do is true parallel flow when the outlet temperatures will equal each other. Usually add additional backs of exchangers due to pressure drop limitations.
If you an infinite number of small exchangers and you put them in series – then you will approach true counter flow service and the hot side outlet temp will equal the cold side inlet temp. A good examples is the feed/effluent exchangers in the NHT where the desire is to maximize heating of the feed and cooling of the reactor effluent.
If you have an infinite number of small exchangers and you put them in parallel – then the best you can do is true parallel flow when the outlet temperatures will equal each other. Usually add additional backs of exchangers due to pressure drop limitations.
Scenario: I have two identical heat exchangers that I can either hook up in series or parallel. Outlet temperature is not a concern. Maximum heat transfer (efficiency) is the objective. Inlet temperature would probably be around 220°F with a flow rate of ~4gpm and pressure of 80psig. The cooling side of the heat exchanger is the ambient air being forced over the surface of the heat exchanger.
Would I get more heat rejection hooking up in parallel or series?
Bob Loblaw stated that typically heat exchangers out here would be applied in series. However, I do not know if that is the general case where the objective is a target outlet temperature or if that is the more efficient setup.
My original hypothesis was that the parallel setup would be more efficient as the mean temperature differential between the heat exchangers and the air would be greatest. In a series configuration, the 2nd heat exchanger would have a lower temperature differential with the ambient air than the 1st heat exchanger or in the case of applying both of them in parallel.
I would think this would be similar to a Cooling Water Tower facility where the cells are setup in parallel (Cooling Water Tower #1). In the Cooling Water Tower case, I would think they would be setup for efficiency (max heat rejection).
So, for the final answer in the case of my identical heat exchangers, what would be the ideal setup?
Would I get more heat rejection hooking up in parallel or series?
Bob Loblaw stated that typically heat exchangers out here would be applied in series. However, I do not know if that is the general case where the objective is a target outlet temperature or if that is the more efficient setup.
My original hypothesis was that the parallel setup would be more efficient as the mean temperature differential between the heat exchangers and the air would be greatest. In a series configuration, the 2nd heat exchanger would have a lower temperature differential with the ambient air than the 1st heat exchanger or in the case of applying both of them in parallel.
I would think this would be similar to a Cooling Water Tower facility where the cells are setup in parallel (Cooling Water Tower #1). In the Cooling Water Tower case, I would think they would be setup for efficiency (max heat rejection).
So, for the final answer in the case of my identical heat exchangers, what would be the ideal setup?
The parallel arrangement is mainly used when pressure drop limitations (coupled with length, diameter and baffle spacing limits) force a reduction in shell-side velocity and thus throughput per unit. For identical units, each exchanger may be separately analyzed using its proportional share of the flow rates.
The purely series arrangement is mainly useful when
a. The single shell with multiple tube passes gives too low a value for F, as previously discussed in the Mean Temperature Difference Concept,
b. There are limitations on shell length and/or diameter, requiring the total area to be disposed in more than one shell.
The shells are usually identical for economy in manufacturing and ease and flexibility of installation, operation and maintenance....
etc.
The purely series arrangement is mainly useful when
a. The single shell with multiple tube passes gives too low a value for F, as previously discussed in the Mean Temperature Difference Concept,
b. There are limitations on shell length and/or diameter, requiring the total area to be disposed in more than one shell.
The shells are usually identical for economy in manufacturing and ease and flexibility of installation, operation and maintenance....
etc.
May 29, 2015, 10:32 AM
#43
Recognize you are dealing with real systems here, not infinite. You are asking "general engineering" questions when you are really interested in application specific results.
1. Series arrangement will absolutely increase pressure drop, more than double.
2. The majority of cooling capacity (which encompasses thermal efficiency) is dependent on frontal area of the coolers. Series vs. Parallel is on an order of magnitude lower in importance, IMO. As long as you have the frontal area and ambient airflow into AND OUT OF the heat exchangers, it's going to be within a few percent of maximum cooling capacity, regardless of plumbing.
The simple question, is 2X or more pressure drop worth that small increase in efficiency? The 4G63 does have excess pressure issues in many cars so maybe it's worth it to run series for you. It also simplifies cooler plumbing.
Point is, I wouldn't get too wrapped up in the theoretical difference here, focus on the practical.
1. Series arrangement will absolutely increase pressure drop, more than double.
2. The majority of cooling capacity (which encompasses thermal efficiency) is dependent on frontal area of the coolers. Series vs. Parallel is on an order of magnitude lower in importance, IMO. As long as you have the frontal area and ambient airflow into AND OUT OF the heat exchangers, it's going to be within a few percent of maximum cooling capacity, regardless of plumbing.
The simple question, is 2X or more pressure drop worth that small increase in efficiency? The 4G63 does have excess pressure issues in many cars so maybe it's worth it to run series for you. It also simplifies cooler plumbing.
Point is, I wouldn't get too wrapped up in the theoretical difference here, focus on the practical.
Jun 20, 2015, 07:52 AM
#44
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well cooling has no become a priority, and im not sure which step to take first (of course its a money issue at this point)
yesterday at NJMP in 85 degree ambient with some decent humidity, i was able to get my oil temp in the pan up to 235-240 degrees in 5-7 laps (25 minute sessions) and i was having to take 2+ slow laps to try and get it back down to 220 just to get 2 more hot laps in before the alarm went off again. i did reinstall the factory bumper duct prior to this event, but it is still partially blocked by my brake duct, as well as my fender liners being pretty torn up so the louvres behind the oil cooler are pretty much gone which may be hindering how much air is pulled through?
stock coolant gauge never budged from dead center. so i have no idea if i should start with a radiator or an oil cooler. i found a super street test of an oem evo rad vs koyo and there was about a 7 degree drop in coolant temp when doing a dyno pull as well as a sustained 60 second speed hold in 4th gear at 5psi of boost...but will that even be worth it?
ambient air net month in south jersey will probably be 10 degrees hotter...
yesterday at NJMP in 85 degree ambient with some decent humidity, i was able to get my oil temp in the pan up to 235-240 degrees in 5-7 laps (25 minute sessions) and i was having to take 2+ slow laps to try and get it back down to 220 just to get 2 more hot laps in before the alarm went off again. i did reinstall the factory bumper duct prior to this event, but it is still partially blocked by my brake duct, as well as my fender liners being pretty torn up so the louvres behind the oil cooler are pretty much gone which may be hindering how much air is pulled through?
stock coolant gauge never budged from dead center. so i have no idea if i should start with a radiator or an oil cooler. i found a super street test of an oem evo rad vs koyo and there was about a 7 degree drop in coolant temp when doing a dyno pull as well as a sustained 60 second speed hold in 4th gear at 5psi of boost...but will that even be worth it?
ambient air net month in south jersey will probably be 10 degrees hotter...
Jun 20, 2015, 09:11 AM
#45
great thread. posting to subscribe.
my tuner advised me to stay with the OEM radiator due to it's efficiency and size. i did some research and found the same as above: aftermarket doesn't seem to work that much better. personally, i've decided to stay OEM.
my tuner advised me to stay with the OEM radiator due to it's efficiency and size. i did some research and found the same as above: aftermarket doesn't seem to work that much better. personally, i've decided to stay OEM.