Answer
Apr 18, 2023 - 05:19 PM
A heat exchanger or oil cooler is not made on the outside. Its made on the inside. We’ve seen sites and old salts with a great deal of experience that say that an oil cooler size is all that matters. That’s really an uninformed answer completely untrue. Heat transfer is based on three things primarily:
Surface area of the cooling tubes (so if the size is the same this cooling area would most often be much the same).
Differential between the cooling fluid and the fluid being cooled (these are environmental circumstances and not related to the cooling device so these remain the same).
Fluid speed of the hot and cold fluid. This is the most important of the three as you can change the amount of cooling you will get by increasing the fluid speed up to the point of erosion. We’ve done this on test boats with engineers and by simply increasing the speed of your fluid pumps you will increase the efficiency of the cooler, dropping the temperature of the engine oil or other cooling fluid.
Fluid speeds can be increased by changing the fluid speed via the pump and also by changing what is called ‘baffling’ on the inside of the cooler. The number of the baffles and how much of the bundle they cover has everything to do with the fluid speed inside of the cooler and therefore significantly impacts proper cooling. In all cases where it is reasonable a responsible aftermarket source would obtain the OEM unit they intend to replace and evaluate the inside of the cooler, duplicating it with much attention to dimensional accuracy so that the fluid speeds and backpressure remain the same.
The term backpressure is another colloquial term in many industries for fluid resistance to movement or fluid friction. Technically there is no such thing as backpressure. It is commonly an increase in pressure due to an incorrectly made cooler or a cooler being used in an unintended way. If you’re measuring the pressure between the pump and the cooler, an incorrectly baffled cooler will have increased pressure which can harm the pumping mechanism. If it has decreased pressure that means that the fluid speed may have decreased to the point where the cooler cannot do its job. And your engine temperatures will tell you if that’s the case.
And here’s the rub: sometimes these standard or same size coolers work just fine when installed. The damage to the pump happens over time and it may be the person you sell your boat to that has to deal with the issue. Standard oil coolers have standard baffling and more frequently than not they are intended to be used as a replacement for an OEM cooler in most cases. They are an emergency replacement or some other interim fix. If someone is trying to sell you a non engineered cooler because they say they know better, you may regret the decision to allow them to proceed. Engineers who work in heat transfer are often very precise in their expectations. Heat transfer is a specialty in mechanical engineering and developing cooling devices is their job. Make sure your cooler is being replaced with an equivalent device.
©2023 Mr. Cool Marine LLC
Surface area of the cooling tubes (so if the size is the same this cooling area would most often be much the same).
Differential between the cooling fluid and the fluid being cooled (these are environmental circumstances and not related to the cooling device so these remain the same).
Fluid speed of the hot and cold fluid. This is the most important of the three as you can change the amount of cooling you will get by increasing the fluid speed up to the point of erosion. We’ve done this on test boats with engineers and by simply increasing the speed of your fluid pumps you will increase the efficiency of the cooler, dropping the temperature of the engine oil or other cooling fluid.
Fluid speeds can be increased by changing the fluid speed via the pump and also by changing what is called ‘baffling’ on the inside of the cooler. The number of the baffles and how much of the bundle they cover has everything to do with the fluid speed inside of the cooler and therefore significantly impacts proper cooling. In all cases where it is reasonable a responsible aftermarket source would obtain the OEM unit they intend to replace and evaluate the inside of the cooler, duplicating it with much attention to dimensional accuracy so that the fluid speeds and backpressure remain the same.
The term backpressure is another colloquial term in many industries for fluid resistance to movement or fluid friction. Technically there is no such thing as backpressure. It is commonly an increase in pressure due to an incorrectly made cooler or a cooler being used in an unintended way. If you’re measuring the pressure between the pump and the cooler, an incorrectly baffled cooler will have increased pressure which can harm the pumping mechanism. If it has decreased pressure that means that the fluid speed may have decreased to the point where the cooler cannot do its job. And your engine temperatures will tell you if that’s the case.
And here’s the rub: sometimes these standard or same size coolers work just fine when installed. The damage to the pump happens over time and it may be the person you sell your boat to that has to deal with the issue. Standard oil coolers have standard baffling and more frequently than not they are intended to be used as a replacement for an OEM cooler in most cases. They are an emergency replacement or some other interim fix. If someone is trying to sell you a non engineered cooler because they say they know better, you may regret the decision to allow them to proceed. Engineers who work in heat transfer are often very precise in their expectations. Heat transfer is a specialty in mechanical engineering and developing cooling devices is their job. Make sure your cooler is being replaced with an equivalent device.
©2023 Mr. Cool Marine LLC
