ACDelco PF64 - pics
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Patman
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So here is what I'm wondering now, if a filter has the type of media that allows it to flow extremely well, such as with a K&N oil filter, does that mean that it can get away with having a lower bypass pressure setting, because it'll not go into bypass as frequently as a more restrictive media? (like the PF64 probably has).
In other words, lets say the K&N flows twice as much as the AC Delco PF64, does it's 11psi bypass now equal that of the PF64's 22psi bypass?
In other words, lets say the K&N flows twice as much as the AC Delco PF64, does it's 11psi bypass now equal that of the PF64's 22psi bypass?
Originally Posted By: Patman
So here is what I'm wondering now, if a filter has the type of media that allows it to flow extremely well, such as with a K&N oil filter, does that mean that it can get away with having a lower bypass pressure setting, because it'll not go into bypass as frequently as a more restrictive media? (like the PF64 probably has).
In other words, lets say the K&N flows twice as much as the AC Delco PF64, does it's 11psi bypass now equal that of the PF64's 22psi bypass?
A filter that flows well and doesn't produce as much delta-p doesn't really need a very high bypass valve setting. However, the bypass valve should be set high enough to give adeqate headroom so it rarely goes into bypass.
Obviously, the thicker the oil and the more oil volume going through the filter (ie, high volume oil pump at high RPM), both of those factors contribute to creating more delta-p. I could see where a car like a Vette might have higher oil viscosity and high pump flow (especially with track use), but not some of the engines GM has put on the "needs a 22 PSI bypass valve" list. I think they are just going that route to make it easier to cover all thier models with one blanket recommendation. Or they have become concerned about people doing high revs shortly after a really cold start-up.
Subaru has specified their OEM filters with a high bypass setting for years, but some of their engines put out some really high oil pump flow. Some aftermarket filter makers now have specific filters for those applications.
Are those OEM filters more flow restrictive than some of the aftermarket filters? And if so, is that the main reason the bypass valve is set higher? We would never know unless we had a flow vs delta-p graph for a bunch of different brands of filters to compare at both cold and hot oil temperature. That data is very hard to find, and most likely held tight ("propriatary") by manufacturers.
So here is what I'm wondering now, if a filter has the type of media that allows it to flow extremely well, such as with a K&N oil filter, does that mean that it can get away with having a lower bypass pressure setting, because it'll not go into bypass as frequently as a more restrictive media? (like the PF64 probably has).
In other words, lets say the K&N flows twice as much as the AC Delco PF64, does it's 11psi bypass now equal that of the PF64's 22psi bypass?
A filter that flows well and doesn't produce as much delta-p doesn't really need a very high bypass valve setting. However, the bypass valve should be set high enough to give adeqate headroom so it rarely goes into bypass.
Obviously, the thicker the oil and the more oil volume going through the filter (ie, high volume oil pump at high RPM), both of those factors contribute to creating more delta-p. I could see where a car like a Vette might have higher oil viscosity and high pump flow (especially with track use), but not some of the engines GM has put on the "needs a 22 PSI bypass valve" list. I think they are just going that route to make it easier to cover all thier models with one blanket recommendation. Or they have become concerned about people doing high revs shortly after a really cold start-up.
Subaru has specified their OEM filters with a high bypass setting for years, but some of their engines put out some really high oil pump flow. Some aftermarket filter makers now have specific filters for those applications.
Are those OEM filters more flow restrictive than some of the aftermarket filters? And if so, is that the main reason the bypass valve is set higher? We would never know unless we had a flow vs delta-p graph for a bunch of different brands of filters to compare at both cold and hot oil temperature. That data is very hard to find, and most likely held tight ("propriatary") by manufacturers.
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