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By pass filter?
- Thread starter KW
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I think you are referring to the sandwich adapter that get mounted between the engine and an oil filter with two ports, one in and one out. The port comming back from the by-pass filter and meeting up with the hole comming back from the oil filter meets with the same flow properties as the hole comming back from the oil filter faces when it meets up with the port from the by-pass filter. The pressure is the same for both sides. Inside the sandwich adapter it is really two holes under pressure that flow down a third hole.quote:
Originally posted by mangusta1969:
Mykro,
I think Dan's question ... (and mine) is whether the bypass filter can work effectively when feeding the filtered oil back to the return port of a two port sandwich adapter instead of draining into a no pressure area in the oil pan or a valve cover. The return port of dual port sandwich adapter will see almost the same pressure as the feed line from the engine.
It's no different than running oil through a hose, splitting the hose with a Y adapter, running it six feet, then joining them back to one hose with another Y adapter. The pressure affect for the left side is the same for the right side. It's the same for a Y adapter, T adapter and sandwich adapter.
What makes the difference is what is creating the resistance on the end. When the by-pass hose is returned to the sandwich adapter, it has an engine with oil galleys that will have more resistance than emptying into on oil pan.
The other difference is oil in the two return holes of the sandwich adapter will have to compete for space to flow which will affect pressure on both sides equally.
The reason 90% flows through the full flow filter is simply a matter of resistance in the by-pass material.
Both the oil filter return holes and the return port on the sandwich adapter are subjected to the same properties. On one side is an oil pump, and on the other are engine galleys.
I guess the real question is how much oil (in gpm or fractional gpm) will flow through the bypass filter when the filtered oil is returned to:
A. A high pressure area (for example, 55 psi) which is the input to the engine oil galleys
- or -
B. A low pressure area (0-1 psi) at the top or bottom of the oil sump
I talked to a fluids engineer the other day. He reminded me that if a bypass filter's output line is fed into a high pressure area, that its output line pressure will rise to equal that of the high pressure area. This, of course, assumes that the input pressure to the bypass filter exceeds that of the high pressure return area. Oil flow will be reduced due to low difference in the input/output pressures.
If the same bypass filter's output line is fed to a low or no pressure area, there will never be any significant pressure in the output line. Oil flow will be increased due to the large difference in the input/output pressures.
Again, the question really comes down to how much hot oil will flow through a given bypass filter in the two return situations above. Noting that the bypass filter eventually gets "hot" to the touch doesn't tell us much about the oil flow rate through the filter.
A. A high pressure area (for example, 55 psi) which is the input to the engine oil galleys
- or -
B. A low pressure area (0-1 psi) at the top or bottom of the oil sump
I talked to a fluids engineer the other day. He reminded me that if a bypass filter's output line is fed into a high pressure area, that its output line pressure will rise to equal that of the high pressure area. This, of course, assumes that the input pressure to the bypass filter exceeds that of the high pressure return area. Oil flow will be reduced due to low difference in the input/output pressures.
If the same bypass filter's output line is fed to a low or no pressure area, there will never be any significant pressure in the output line. Oil flow will be increased due to the large difference in the input/output pressures.
Again, the question really comes down to how much hot oil will flow through a given bypass filter in the two return situations above. Noting that the bypass filter eventually gets "hot" to the touch doesn't tell us much about the oil flow rate through the filter.
Yes, we are saying the same thing, just with a different twist to make our own point. Pressure is a result of resistance. The by-pass has more resistance. Once the oil passes through the by-pass filter material the resistance drops and so does the pressure. Connecting the hose to the return port will provide the resistance to return the psi back to equal the psi of the oil in the sandwich adapter. Now both sides are at 55psi only at different flow rates.quote:
Originally posted by mangusta1969:
I talked to a fluids engineer the other day. He reminded me that if a bypass filter's output line is fed into a high pressure area, that its output line pressure will rise to equal that of the high pressure area. This, of course, assumes that the input pressure to the bypass filter exceeds that of the high pressure return area. Oil flow will be reduced due to low difference in the input/output pressures.
If the flow rate of the by-pass is tested to be 10% of the full flow and the oil pump pumps at a rate of 3 gallons per minute, then the full flow will flow 2.7 gpm and the by-pass will flow 0.3 gpm to the engine galleys at 55 psi.
If you direct the hose to the oil pan will the oil pump pump more oil? No, it will pump the same 3 gallons per minute. We all agree that the by-pass is the unit with the greatest amount of resistance in the system. The resistance in the by-pass is greater than the resistance hose on the output side of the by-pass in both situations, so we really have not changed the rate of flow through the by-pass by much.
The difference is that by not returning oil to the sandwich adapter, now 0.3 gallons of oil are going directly to the oil pan and by-passing the engine.
I'm not saying this is a problem, or that returning to the sandwich is better because it delivers more oil to the engine. I doubt that any engine manufacturer would design an oil pump to deliver the exact amount of oil the engine needs for lubrication and loss of 10% would be a problem.
A good example is Ford tests the F-150 in Alaska. Talk about an oil flow problem. Do you suppose the engine's by-pass valve opens up when the engine is started at -60*? I don't recall the lowest temp a Triton engine will start at, but I'm thinking it was -60*.
Although this is not a major factor, I disagree, the oil pump will pump somewhat more oil if it sees less overall head pressure. You can look at some representative specs for this by looking at positive displacement deep well water pumps and the amount of gallons pumped vs lift heights.quote:
posted by greencrew
If you direct the hose to the oil pan will the oil pump pump more oil? No, it will pump the same 3 gallons per minute.
The amount of water pumped by these deep well pumps is greatly reduced with high lifts (higher pressure) associated with greater well depths.
However the main factor to consider is that the flow rate THROUGH the bypass filter will also not be at the same gpm rate when the oil is being returned to a high pressure area. In other words, it is not going to remain at 10% (.3 gpm) of the full flow filter in our examples of (55 psi return vs 0 psi return). The higher psi return situation will have significant reductions in oil flow via the bypass line; the flow of the full flow filter may increase to 2.9 gpm or more, as it is relatively less restrictive than the now even more restricted bypass line.
As an example, let's look at some likely numbers for each case:
Bypass filter flows 10% of full flow filter under "no pressure return situation"
Bypass filter flows 1% of full flow filter under "55 psi return situation"
Condition A.
No pressure return situation for bypass filter
Oil pump flow 3 gpm
Full flow filter: 2.7 gpm
Bypass filter flow: .3 gpm
Condition B.
55 psi return situation for bypass filter:
Oil pump flow 2.9 gpm (increased overall head pressure causes reduced flow from the oil pump)
Full flow filter 2.87 gpm
Bypass filter .03 gpm
Whether or not these hypothetical numbers are off by 10, 20, or 50% is not really an issue. What we really need to know is how much oil will flow through a given bypass filter element at several different pressure differentials for that filter.
I will see if I can get some information like this on desired pressure differentials and bypass flow rates rom the bypass filter manufacturers.
I agree, our numbers are hypothetical for the sake of discussion. The numbers I've heard are 10% and 20%. I've always believed the actual numbers change as the temp of the oil changes. On a cold start the oil is not flowing through the by-pass and is forced through the full flow, which also has to much restriction and oil is forced to flow through the filter's by-pass valve.
As for how much oil is pumped, I had to look at slalom44's comments in another related thread: "Oil pumps aren't separate underpowered electric motors that bog down flow with increased resistance. They are powered by the camshaft (in most cars) and therefore the flow is relatively constant regardless of backpressure at the oil pump."
The math of deep well pumps does not apply here, because we are not working with vertical columns. The problem with gallons pumped vs lift hight is due to the fact that the column of water exerts downword pressure against the bottom of the column, and the pump, which increases with hight. The 55 psi in the sandwich adapter is not pushing back against the pump, rather it is created by the pump.
Even in water that is not being pumped the pressure increases as you dive down deeper.
[ December 24, 2003, 11:08 PM: Message edited by: greencrew ]
As for how much oil is pumped, I had to look at slalom44's comments in another related thread: "Oil pumps aren't separate underpowered electric motors that bog down flow with increased resistance. They are powered by the camshaft (in most cars) and therefore the flow is relatively constant regardless of backpressure at the oil pump."
The math of deep well pumps does not apply here, because we are not working with vertical columns. The problem with gallons pumped vs lift hight is due to the fact that the column of water exerts downword pressure against the bottom of the column, and the pump, which increases with hight. The 55 psi in the sandwich adapter is not pushing back against the pump, rather it is created by the pump.
Even in water that is not being pumped the pressure increases as you dive down deeper.
[ December 24, 2003, 11:08 PM: Message edited by: greencrew ]
Perhaps I used a bad example (pump flow vs pressure/water column height) previously, but the physical properties at work are pretty similar. I used the well pump example because many people have seen published flow and pressure specs for this type of pump. No such information is readily available for engine oil pumps.
In the engine example, the "55 psi" pressure area for the output of the bypass filter into a return port of the sandwich adapter exists solely due to the flow restrictions imposed by the engines oil galleys and bearings. This high pressure area is similar to that caused by the weight of the water column above the deep well pump. Yes, different formulas would apply for theoretical calculations between the two examples.
In both cases, (engine oil pump and deep well water pump) each pump's output pressure would be essentially zero without the resistance to flow from the external factors (restricted bearing passages or weight of vertical water column and pipe restrictions). Think of a garden hose - with the same city water pressure source at the house, you will measure little to no pressure inside the hose until you restrict the water flow with your thumb. Increased pressures are caused by the flow restriction, not the pump itself. I think we are on the same trail here, because you said in a previous post that "pressure was caused by resistance."
In all of these cases, the maximum pressure that can build up is controlled by the maximum head pressure of the source. Perhaps that is what you meant to say about the 55 psi return pressure being "created by the oil pump".
Anyway, my concern here is about the reduced oil flow that the bypass filter will have when returning oil to a 50-55 psi area (sandwich adapter return), versus the same filter returning oil to a 0 psi area (e.g. valve cover return).
The other major factor is any oil flow restrictions that filter designers have implemented within the sandwich or other adapters. Because these extra flow restrictions are being inserted after the engine's internal oil pressure/flow control valve, they are somewhat reducing oil flow to the engine's bearing surfaces. The only way to know whether this reduction is significant or not to your engine's bearings is to know what the actual flow and pressure numbers are.
We do know that the several bypass filters' measured maximum flow rate (typically .25 gpm at 50 psi input) is pretty insignificant when compared to a modern engine's overall oil flow (5-10 gpm or more).
In the engine example, the "55 psi" pressure area for the output of the bypass filter into a return port of the sandwich adapter exists solely due to the flow restrictions imposed by the engines oil galleys and bearings. This high pressure area is similar to that caused by the weight of the water column above the deep well pump. Yes, different formulas would apply for theoretical calculations between the two examples.
In both cases, (engine oil pump and deep well water pump) each pump's output pressure would be essentially zero without the resistance to flow from the external factors (restricted bearing passages or weight of vertical water column and pipe restrictions). Think of a garden hose - with the same city water pressure source at the house, you will measure little to no pressure inside the hose until you restrict the water flow with your thumb. Increased pressures are caused by the flow restriction, not the pump itself. I think we are on the same trail here, because you said in a previous post that "pressure was caused by resistance."
In all of these cases, the maximum pressure that can build up is controlled by the maximum head pressure of the source. Perhaps that is what you meant to say about the 55 psi return pressure being "created by the oil pump".
Anyway, my concern here is about the reduced oil flow that the bypass filter will have when returning oil to a 50-55 psi area (sandwich adapter return), versus the same filter returning oil to a 0 psi area (e.g. valve cover return).
The other major factor is any oil flow restrictions that filter designers have implemented within the sandwich or other adapters. Because these extra flow restrictions are being inserted after the engine's internal oil pressure/flow control valve, they are somewhat reducing oil flow to the engine's bearing surfaces. The only way to know whether this reduction is significant or not to your engine's bearings is to know what the actual flow and pressure numbers are.
We do know that the several bypass filters' measured maximum flow rate (typically .25 gpm at 50 psi input) is pretty insignificant when compared to a modern engine's overall oil flow (5-10 gpm or more).
Anytime a fluid flows it is subject to pressure, and there is less pressure on the end of the hose the fluid is flowing to, (gravity flow excluded.) The psi in a garden hose is significantly reduced, but still there. Even water in a pond is subject to atmospheric pressure of 14.7 per Ken's post:
2 1/2 feet of column. At 100' the pressure at the bottom of the column (near the pump) is 54.7 psi. If the pump creates a pressure of 55 psi at the bottom of the column the difference is 55-54.7 or .3 psi to move the water.
In both the sandwich adapter and the oil pan the oil is at 14.7 atmospheric pressure. If the pump creates a pressure of 55 psi the difference is 55 - 14.7 or 40.3 psi. The difference between the two will be the resistance designed into each. Since the DB and sandwich adapter have more hardware and oil galleys at the end, the resistance will be higher and the pressure will go up accordingly.
Pressure in the sandwich adapter will be created by both the return oil flowing from the by-pass (10%) and the return oil flowing from the full flow filter (90%). That pressure will be less than 55 psi. The pressure in a hose to the oil pan will be even more less than 55 psi due to lack of resistance. End of 5 psi examples.
Generally speaking, since there is significant resistance in the sandwich adapter/by-pass, one of two things will happen. Either flow will slow, or pressure will increase, as a result of that resistance. In the case of a cold engine start, or high rpm, you can see pressure increase on your gage.
For the flow to be reduced one of two things need to happen. Either the pump is slowed down, or the oil leaks out of the system. In an electronic controlled engine the computer increases fuel to maintain rpm. We do know that there is a slight amount of oil that sneaks past the gears of an engine oil pump, but believe that amount not to be significant.
The only remaining leak of oil would be the by-pass safety system in the engine. I don't know the number, but I thought it was high, as it is designed to protect the oil filter from damage, not to control oil flow.
[ December 27, 2003, 07:48 PM: Message edited by: greencrew ]
Water in a vertical column is subject to atmosphere pressure of 14.7 plus 1 psi for everyquote:
It takes about a 2-1/2 foot vertical column of oil to equal 1 psi. In any case, the additional 3" drop of oil in the hose down to the pan would exactly equal entering the oil pan 3" under the oil surface.
A 33' tall column of water exerts one atmosphere of pressure...14.7 psi... Ken
2 1/2 feet of column. At 100' the pressure at the bottom of the column (near the pump) is 54.7 psi. If the pump creates a pressure of 55 psi at the bottom of the column the difference is 55-54.7 or .3 psi to move the water.
In both the sandwich adapter and the oil pan the oil is at 14.7 atmospheric pressure. If the pump creates a pressure of 55 psi the difference is 55 - 14.7 or 40.3 psi. The difference between the two will be the resistance designed into each. Since the DB and sandwich adapter have more hardware and oil galleys at the end, the resistance will be higher and the pressure will go up accordingly.
Pressure in the sandwich adapter will be created by both the return oil flowing from the by-pass (10%) and the return oil flowing from the full flow filter (90%). That pressure will be less than 55 psi. The pressure in a hose to the oil pan will be even more less than 55 psi due to lack of resistance. End of 5 psi examples.
Generally speaking, since there is significant resistance in the sandwich adapter/by-pass, one of two things will happen. Either flow will slow, or pressure will increase, as a result of that resistance. In the case of a cold engine start, or high rpm, you can see pressure increase on your gage.
For the flow to be reduced one of two things need to happen. Either the pump is slowed down, or the oil leaks out of the system. In an electronic controlled engine the computer increases fuel to maintain rpm. We do know that there is a slight amount of oil that sneaks past the gears of an engine oil pump, but believe that amount not to be significant.
The only remaining leak of oil would be the by-pass safety system in the engine. I don't know the number, but I thought it was high, as it is designed to protect the oil filter from damage, not to control oil flow.
[ December 27, 2003, 07:48 PM: Message edited by: greencrew ]
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