Engine Building Services at DBTuned.
08-17-2010, 09:24 AM
#48
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Call Redline Oil, they'll help you out.
Looser clearance = lower engine oil temp?
Tighter clearance = higher oil temp?
If the engine oil is getting hotter, where is heat coming from?
Tighter clearance = higher oil temp?
If the engine oil is getting hotter, where is heat coming from?
08-17-2010, 09:40 AM
#49
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Pressure would be dictated by the size of the orifice. I this case the the total sum of the oiled parts. That spec remains constant. The oil viscosity, say 40w for instance, is 40w at operating temperature. This is also a constant. The pump is variable speed and variable pressure. That pressure once again is determined by what it has to push against. Take a garden hose for instance, if you turn the water on and let it flow, you end up with high volume, low pressure. Now cover half of it with your finger, you've increased the pressure in the hose, you've also increased the velocity/pressure of the fluid exiting the hose. This velocity has the potential to do work. In this case the work is floating the journal. Within the rod crank bearing assembly pressure is what floats the journal. Not the oil. Oil is just a fluid. It has similar properties to other fluids. One of which is it's resistance to compression. We all know you cannot compress a fluid, (compress=pressure). This is what enables hydraulics to do work. We supply a pressure to a fluid with the intention of performing work. Oil does a few things, removes heat, lubricates, protects, transfers energy.In this case it transfer energy provided by the pump to the journal. That energy is the oil wedge between the metal parts. If you increase the size of the orifice (remove finger from garden hose) you are removing energy from the fluid reducing it's potential to conduct work. You cannot adjust one with out affecting the other. Every component of a hydraulic system is dependent on the other.
08-17-2010, 09:57 AM
#50
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Call Redline Oil, they'll help you out.
Looser clearance = lower engine oil temp?
Tighter clearance = higher oil temp?
If the engine oil is getting hotter, where is heat coming from?
Looser clearance = lower engine oil temp?
Tighter clearance = higher oil temp?
If the engine oil is getting hotter, where is heat coming from?
08-17-2010, 11:02 AM
#52
Do you realize that the first number (5/10) is the viscosity of the oil when its cold and the second number (40) is the viscosity of the oil at operating temperature? Understanding this, how would a 10-40 oil be more appropriate for track use where you are always at operating temperature? The two oils should act the same at this temperature correct?
-- Ed
08-17-2010, 11:21 AM
#53
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?
Do you realize that the first number (5/10) is the viscosity of the oil when its cold and the second number (40) is the viscosity of the oil at operating temperature? Understanding this, how would a 10-40 oil be more appropriate for track use where you are always at operating temperature? The two oils should act the same at this temperature correct?
-- Ed
Do you realize that the first number (5/10) is the viscosity of the oil when its cold and the second number (40) is the viscosity of the oil at operating temperature? Understanding this, how would a 10-40 oil be more appropriate for track use where you are always at operating temperature? The two oils should act the same at this temperature correct?
-- Ed
08-17-2010, 11:22 AM
#54
Pressure would be dictated by the size of the orifice. I this case the the total sum of the oiled parts. That spec remains constant. The oil viscosity, say 40w for instance, is 40w at operating temperature. This is also a constant. The pump is variable speed and variable pressure. That pressure once again is determined by what it has to push against. Take a garden hose for instance, if you turn the water on and let it flow, you end up with high volume, low pressure. Now cover half of it with your finger, you've increased the pressure in the hose, you've also increased the velocity/pressure of the fluid exiting the hose. This velocity has the potential to do work. In this case the work is floating the journal. Within the rod crank bearing assembly pressure is what floats the journal. Not the oil. Oil is just a fluid. It has similar properties to other fluids. One of which is it's resistance to compression. We all know you cannot compress a fluid, (compress=pressure). This is what enables hydraulics to do work. We supply a pressure to a fluid with the intention of performing work. Oil does a few things, removes heat, lubricates, protects, transfers energy.In this case it transfer energy provided by the pump to the journal. That energy is the oil wedge between the metal parts. If you increase the size of the orifice (remove finger from garden hose) you are removing energy from the fluid reducing it's potential to conduct work. You cannot adjust one with out affecting the other. Every component of a hydraulic system is dependent on the other.
Very good explanation. The one thing to remember is that pressure and flow have to do with resistance (the size of orifice) as well as the viscosity of the fluid. With a larger orifice (looser clearance), you can maintain the same oil pressure by increasing the viscosity of the fluid (oil in this case).
The other thing to remember is that pressure, is in essence, resistance to flow. So a higher pressure means that less fluid is actually flowing past the orifice. In terms of engine bearings, the oil is providing pressure to float the journal, and its also cooling the journal and bearing surface as it flows through. As you increase pressure, you inhibit the overall flow which also inhibits cooling.
The trick is to find the correct combination of pressure and flow to maintain enough pressure to float the journal while still maintaining enough flow to allow for proper cooling. This combination is very application specific and the clearance spec and oil viscosity chosen both play major roles.
-- Ed
08-17-2010, 11:30 AM
#55
-- Ed
08-17-2010, 12:16 PM
#56
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Ed:
You asked for a recommendation and a I provided one; either weight oil in the brands that we use work just fine.
With regards to your spec on your motors, and with the data that you have gathered, can you please provide us with this information?
There are several local shops/customers campaigning race cars that would take exception to this statement.
FWIW:
The BMW M series engines, with a bearing clearance of .0007in. requires 10-60 oil.
You asked for a recommendation and a I provided one; either weight oil in the brands that we use work just fine.
With regards to your spec on your motors, and with the data that you have gathered, can you please provide us with this information?
Originally Posted by Me
Looser clearance = higher/lower engine oil temp?
Tighter clearance = higher/lower engine oil temp?
Tighter clearance = higher/lower engine oil temp?
Originally Posted by Ed
The other thing to remember is that pressure, is in essence, resistance to flow. So a higher pressure means that less fluid is actually flowing past the orifice. In terms of engine bearings, the oil is providing pressure to float the journal, and its also cooling the journal and bearing surface as it flows through. As you increase pressure, you inhibit the overall flow which also inhibits cooling.
There are several local shops/customers campaigning race cars that would take exception to this statement.
FWIW:
The BMW M series engines, with a bearing clearance of .0007in. requires 10-60 oil.
08-17-2010, 12:37 PM
#57
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0w oil are being used due to fuel economy ratings and poor care. People are stupid. They think they can get into a car and turn the key and drive away. A 0w oil would be a very poor choice for any sort of performance application..
The question isn't about the oil weight as both cases are using 40w oil.
Pressure is not the resistance of flow. Pressure is a force applied to a specific area. So psi is just that, 1 psi= 1lb distributed throughout and area of one square inch. SO in this case if two said motors, the only variation is the size of the bearing clearance (more specific area) would result in less force per square inch.
The question isn't about the oil weight as both cases are using 40w oil.
Pressure is not the resistance of flow. Pressure is a force applied to a specific area. So psi is just that, 1 psi= 1lb distributed throughout and area of one square inch. SO in this case if two said motors, the only variation is the size of the bearing clearance (more specific area) would result in less force per square inch.
