Originally Posted By: Gary Allan
I guess you will make me go through all the hardware rigging. I had a great platform to do this lame stuff on with my minivan ..but it goes stolen ..with a good bit of my hardware in it.
..but if you insist.. I will show you low volume with high differential at cold temps ..and I will show you high volume at cold temps with virtually no differential. I will also show you high volume with virtually no differential.
You'll have one out for weasel room. I won't be able to quote volume ..but ..if we're genuinely trying to work on "seeing" ..you'll forgo the opportunity to skate.
How do you think I came up with all this? Just pulled it out of my behind?
No, pal. It's REAL
But your missing the whole point ... it's the VOLUME that's going to make or break this whole discussion. It's the volume in question that makes this situation different than in most cars on the road. Any engine that puts out tons of oil volume is going to have to use a filter that is capable of working correctly in that environment. What kind of filters are used on race cars that put out tons of oil volume? Tell you something.
My whole point here is that the Subaru's oiling system under discussion has uncommonly high volume output for a road car.
If the pump puts out high volume under hot conditions (per the spec), then it will also put out a relatively high volume output under cold oil conditions, as compared to other vehicles. That's because the oiling system is much more unrestrictive than what you are use to seeing and playing with. An unrestrictive system will flow more cold oil than a restrictive one ... and that means the filter used on it will also have to handle a higher cold oil flow volume.
Can you get your head around on just how much 12.4 gpm is? - that's like a wide open garden hose flowing. If the engine only holds say 5 quarts, that means the entire sump volume is exchanged nearly 10 times every minute if the engine was running at 5000 RPM. That's HUGE, and yes somewhat hard to believe - but we have to believe Subaru's specs unless proven false somehow.
If the system on that engine can flow 12.4 gpm with 176 deg F oil, and it only requires 43 psi of supply pressure to do so (much less than the pump's relief pressure setting), then the oiling system can not be a very restrictive compared to some other cars. In fact, it even has some margin in it's performance to flow the full 12.4 gpm with oil colder than 176 deg F, meaning you could increase the oil viscosity to the point until the pump bumps up against its 85 psi relief setting to push the 12.4 gpm through the system.
I think you are under the impression that this oiling system is like 99% of all the others on the road ... forget what you think it should do and look at what it does based on the specs from Subaru.
If you did a test where you could flow 12.4 gpm of oil (at say whatever oil temp keeps the pump just a hair below the 85 psi relief setting), I'm sure you'd see MUCH MORE than a few PSID across the element. That's why Subaru has specified a 23 psi filter bypass setting (at least on their specific OEM filter), so that they ensure the bypass doesn't open when it shouldn't.
I guess you will make me go through all the hardware rigging. I had a great platform to do this lame stuff on with my minivan ..but it goes stolen ..with a good bit of my hardware in it.
..but if you insist.. I will show you low volume with high differential at cold temps ..and I will show you high volume at cold temps with virtually no differential. I will also show you high volume with virtually no differential.
You'll have one out for weasel room. I won't be able to quote volume ..but ..if we're genuinely trying to work on "seeing" ..you'll forgo the opportunity to skate.
How do you think I came up with all this? Just pulled it out of my behind?
But your missing the whole point ... it's the VOLUME that's going to make or break this whole discussion. It's the volume in question that makes this situation different than in most cars on the road. Any engine that puts out tons of oil volume is going to have to use a filter that is capable of working correctly in that environment. What kind of filters are used on race cars that put out tons of oil volume? Tell you something.
My whole point here is that the Subaru's oiling system under discussion has uncommonly high volume output for a road car.
If the pump puts out high volume under hot conditions (per the spec), then it will also put out a relatively high volume output under cold oil conditions, as compared to other vehicles. That's because the oiling system is much more unrestrictive than what you are use to seeing and playing with. An unrestrictive system will flow more cold oil than a restrictive one ... and that means the filter used on it will also have to handle a higher cold oil flow volume.
Can you get your head around on just how much 12.4 gpm is? - that's like a wide open garden hose flowing. If the engine only holds say 5 quarts, that means the entire sump volume is exchanged nearly 10 times every minute if the engine was running at 5000 RPM. That's HUGE, and yes somewhat hard to believe - but we have to believe Subaru's specs unless proven false somehow.
If the system on that engine can flow 12.4 gpm with 176 deg F oil, and it only requires 43 psi of supply pressure to do so (much less than the pump's relief pressure setting), then the oiling system can not be a very restrictive compared to some other cars. In fact, it even has some margin in it's performance to flow the full 12.4 gpm with oil colder than 176 deg F, meaning you could increase the oil viscosity to the point until the pump bumps up against its 85 psi relief setting to push the 12.4 gpm through the system.
I think you are under the impression that this oiling system is like 99% of all the others on the road ... forget what you think it should do and look at what it does based on the specs from Subaru.
If you did a test where you could flow 12.4 gpm of oil (at say whatever oil temp keeps the pump just a hair below the 85 psi relief setting), I'm sure you'd see MUCH MORE than a few PSID across the element. That's why Subaru has specified a 23 psi filter bypass setting (at least on their specific OEM filter), so that they ensure the bypass doesn't open when it shouldn't.