I have a crazy oil pressure question for the mechs in here.
#11
06-10-2009 | 04:35 PM
Road Warrior
Joined: Nov 2008
Posts: 1,296
Likes: 1
From: Cheltenham, UK
I am no expert in the specific design of the engine so I am reluctant to speculate on the damage that overpressurisation will achieve, but...
I don't believe the damage will manifest itself as seal damage as the seals (and certainly gaskets) are all at crank case pressure which is vented, hence atmospheric pressure irrespective of pump pressure.
From purely a hydraulics perspective, Power = Pressure x Flow. The pumps are positive and fixed displacement pumps, which means the flow they deliver will be consistant for a given engine RPM irrespective of pressure (in theory). So, practically speaking by drawing the extra pressure you require more power to turn the pump so you will suffer a loss in brake HP, but most importantly you are doing no work with that extra power so it goes entirely to heat, so your engine will run hotter.
How much hotter and how much power loss I cannot so as I do not know the displacement of the pumps, but the bottom line is you are losing both ways.
In addition to this, I would be concerned about excessive wear on the pump as they are almsot certainly optomised for lower pressures
I don't believe the damage will manifest itself as seal damage as the seals (and certainly gaskets) are all at crank case pressure which is vented, hence atmospheric pressure irrespective of pump pressure.
From purely a hydraulics perspective, Power = Pressure x Flow. The pumps are positive and fixed displacement pumps, which means the flow they deliver will be consistant for a given engine RPM irrespective of pressure (in theory). So, practically speaking by drawing the extra pressure you require more power to turn the pump so you will suffer a loss in brake HP, but most importantly you are doing no work with that extra power so it goes entirely to heat, so your engine will run hotter.
How much hotter and how much power loss I cannot so as I do not know the displacement of the pumps, but the bottom line is you are losing both ways.
In addition to this, I would be concerned about excessive wear on the pump as they are almsot certainly optomised for lower pressures
#12
06-10-2009 | 08:17 PM
Thread Starter
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Road Warrior
Joined: Jun 2008
Posts: 1,282
Likes: 2
From: Yukon, OK
I am no expert in the specific design of the engine so I am reluctant to speculate on the damage that overpressurisation will achieve, but...
I don't believe the damage will manifest itself as seal damage as the seals (and certainly gaskets) are all at crank case pressure which is vented, hence atmospheric pressure irrespective of pump pressure.
From purely a hydraulics perspective, Power = Pressure x Flow. The pumps are positive and fixed displacement pumps, which means the flow they deliver will be consistant for a given engine RPM irrespective of pressure (in theory). So, practically speaking by drawing the extra pressure you require more power to turn the pump so you will suffer a loss in brake HP, but most importantly you are doing no work with that extra power so it goes entirely to heat, so your engine will run hotter.
How much hotter and how much power loss I cannot so as I do not know the displacement of the pumps, but the bottom line is you are losing both ways.
In addition to this, I would be concerned about excessive wear on the pump as they are almsot certainly optomised for lower pressures
I don't believe the damage will manifest itself as seal damage as the seals (and certainly gaskets) are all at crank case pressure which is vented, hence atmospheric pressure irrespective of pump pressure.
From purely a hydraulics perspective, Power = Pressure x Flow. The pumps are positive and fixed displacement pumps, which means the flow they deliver will be consistant for a given engine RPM irrespective of pressure (in theory). So, practically speaking by drawing the extra pressure you require more power to turn the pump so you will suffer a loss in brake HP, but most importantly you are doing no work with that extra power so it goes entirely to heat, so your engine will run hotter.
How much hotter and how much power loss I cannot so as I do not know the displacement of the pumps, but the bottom line is you are losing both ways.
In addition to this, I would be concerned about excessive wear on the pump as they are almsot certainly optomised for lower pressures
#13
06-10-2009 | 08:44 PM
Banned
Joined: Mar 2007
Posts: 3,706
Likes: 6
From: Woodstock, Ont , Can
I am no expert in the specific design of the engine so I am reluctant to speculate on the damage that overpressurisation will achieve, but...
I don't believe the damage will manifest itself as seal damage as the seals (and certainly gaskets) are all at crank case pressure which is vented, hence atmospheric pressure irrespective of pump pressure.
From purely a hydraulics perspective, Power = Pressure x Flow. The pumps are positive and fixed displacement pumps, which means the flow they deliver will be consistant for a given engine RPM irrespective of pressure (in theory). So, practically speaking by drawing the extra pressure you require more power to turn the pump so you will suffer a loss in brake HP, but most importantly you are doing no work with that extra power so it goes entirely to heat, so your engine will run hotter.
How much hotter and how much power loss I cannot so as I do not know the displacement of the pumps, but the bottom line is you are losing both ways.
In addition to this, I would be concerned about excessive wear on the pump as they are almsot certainly optomised for lower pressures
I don't believe the damage will manifest itself as seal damage as the seals (and certainly gaskets) are all at crank case pressure which is vented, hence atmospheric pressure irrespective of pump pressure.
From purely a hydraulics perspective, Power = Pressure x Flow. The pumps are positive and fixed displacement pumps, which means the flow they deliver will be consistant for a given engine RPM irrespective of pressure (in theory). So, practically speaking by drawing the extra pressure you require more power to turn the pump so you will suffer a loss in brake HP, but most importantly you are doing no work with that extra power so it goes entirely to heat, so your engine will run hotter.
How much hotter and how much power loss I cannot so as I do not know the displacement of the pumps, but the bottom line is you are losing both ways.
In addition to this, I would be concerned about excessive wear on the pump as they are almsot certainly optomised for lower pressures
Ron
#16
06-11-2009 | 10:25 PM
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Joined: Jul 2008
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Likes: 67
One of the reasons the newer 96 inch twins need to idle at 950-1000 rpms is to address the problem of low oil flow at low rpms. Most of us have noticed that the newer fuel injection bikes do not have that old familiar "pototo-potato" exhause note. Those older carbed bikes would idle at 750-850 rpms or so. The newer bikes need a few more rpms to keep oil flowing across the bottom skirts of the pistonians. They seem to be happy with 32lbs or a wee bit more at cruising speed and 8 lbs or so at hot idle. If your bike shows something like that then all in Harleyville should be happy.
#17
06-11-2009 | 11:08 PM
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Road Warrior
Joined: Jun 2008
Posts: 1,282
Likes: 2
From: Yukon, OK
One of the reasons the newer 96 inch twins need to idle at 950-1000 rpms is to address the problem of low oil flow at low rpms. Most of us have noticed that the newer fuel injection bikes do not have that old familiar "pototo-potato" exhause note. Those older carbed bikes would idle at 750-850 rpms or so. The newer bikes need a few more rpms to keep oil flowing across the bottom skirts of the pistonians. They seem to be happy with 32lbs or a wee bit more at cruising speed and 8 lbs or so at hot idle. If your bike shows something like that then all in Harleyville should be happy.
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