I have a Focus ZX3 (2.0 DOHC Zetec) and would like to fit a larger filter for the reason outlined in this thread. The Zetec filter has a 16 psi bypass valve according to Wix. The larger SBF filter has a bypass valve (I was incorrect in the other thread) but it is set at 11 psi, again per Wix. Will this be a problem? Last thing I want is oil bypassing the filter a lot. Thanks.
Bypass Valve PSI question
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We're unsure yet how much a bypass actually is in use. The only thing that may happen is that you would be changing it out earlier ...or so I would imagine. If you're one of those who changes your oil and filter more often than is recommended ..or do a time type OCI ..then you're probably not saturating the filter enough to create the PSID needed to open the bypass valve.
My belief is that the bypass valve is more for protecting the media from excessive PSID than it is for anything else...or at least, so far, that's how I think it plays out. If you don't reach the pressure relief in the oil pump, the flow is identical regardless of the filter's bypass valve setting. It just limits the forced velocity of the oil through the media.
That is, any filter setup with a high bypass valve setting is obviously capable of withstanding that PSID.
I would do it without reservations (that's me). If you're of the paranoid type personality for things that you haven't quite indexed in experience (an understandable Chicken Little syndrome) then I would swap it out more often until some hard data from my filter bypass valve test is in.
[ February 27, 2005, 12:13 PM: Message edited by: Gary Allan ]
My belief is that the bypass valve is more for protecting the media from excessive PSID than it is for anything else...or at least, so far, that's how I think it plays out. If you don't reach the pressure relief in the oil pump, the flow is identical regardless of the filter's bypass valve setting. It just limits the forced velocity of the oil through the media.
That is, any filter setup with a high bypass valve setting is obviously capable of withstanding that PSID.
I would do it without reservations (that's me). If you're of the paranoid type personality for things that you haven't quite indexed in experience (an understandable Chicken Little syndrome) then I would swap it out more often until some hard data from my filter bypass valve test is in.
[ February 27, 2005, 12:13 PM: Message edited by: Gary Allan ]
Great post Gary! Thanks for helping me out.
So in reality, the 5 psi difference between the Zetec and SBF filter is most likely well below the operating pressure differential of the filter and therefore nothing to worry about.
The only question I have left is will a large filter be more of a restriction or less of one? I am trying not to carry any preconceptions from air filters where the bigger is better theory holds true.
So in reality, the 5 psi difference between the Zetec and SBF filter is most likely well below the operating pressure differential of the filter and therefore nothing to worry about.
The only question I have left is will a large filter be more of a restriction or less of one? I am trying not to carry any preconceptions from air filters where the bigger is better theory holds true.
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That's my opinion based on adaptive data.
Since you're going from a 16 to an 11 (I got that reversed initially) the WORST effect that I could see is that you may open the bypass sooner as it accumulates particles. The size difference should give you more gms of holding capacity. Normal/typical operation shouldn't be effected, IMHO.
btw- don't they offer a sandwich heat exchanger for the Ztech??? The type that plumbs to the heater hoses???
Every filter that I looked up for your engine shares the common 3/4-16 thread. You should be able to hook up with one of these fairly cheaply. This will stabalize your oil temp a good bit ..letting your coolant thermostat pretty much be the master conductor in your cooling/lubrication symphony....
Since you're going from a 16 to an 11 (I got that reversed initially) the WORST effect that I could see is that you may open the bypass sooner as it accumulates particles. The size difference should give you more gms of holding capacity. Normal/typical operation shouldn't be effected, IMHO.
btw- don't they offer a sandwich heat exchanger for the Ztech??? The type that plumbs to the heater hoses???
Every filter that I looked up for your engine shares the common 3/4-16 thread. You should be able to hook up with one of these fairly cheaply. This will stabalize your oil temp a good bit ..letting your coolant thermostat pretty much be the master conductor in your cooling/lubrication symphony....
There is a sandwich plate heat exchanger for the Zetec of the Focus SVT, however it is so limited in size that it quickly runs of capacity to remove the heat of the oil. I have thought about a larger, non-OEM exchanger but again, the level of complexity is daunting. If I can pic up an SVT unit out of a junkyard I may give it a go just to see.
EDIT - I bought a Mobil1 SBF filter just to see how it fits.
[ February 27, 2005, 03:35 PM: Message edited by: teamDFL ]
EDIT - I bought a Mobil1 SBF filter just to see how it fits.
[ February 27, 2005, 03:35 PM: Message edited by: teamDFL ]
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The options are only limited by your wallet. I'm currently working on adapting one of these to my Caravan
I'll just hack the hoses and fit them with AN/JIC ends and plumb them to a Permacool sandwhich. It's easy if your rad hose is the right diameter and you've got enough room to fit the unit. The nice thing about the sandwich exchangers is that you don't need anything except longer heater hoses.
There are a few more oil/coolant coolers out there (quite a few) that can be had in a variety of configurations/sizes. For that matter, if your situation permits, you can stack the OEM exchangers and go remote for your filter.
I'll just hack the hoses and fit them with AN/JIC ends and plumb them to a Permacool sandwhich. It's easy if your rad hose is the right diameter and you've got enough room to fit the unit. The nice thing about the sandwich exchangers is that you don't need anything except longer heater hoses.
There are a few more oil/coolant coolers out there (quite a few) that can be had in a variety of configurations/sizes. For that matter, if your situation permits, you can stack the OEM exchangers and go remote for your filter.
Thanks for the help, however I am confused by the above statement. I reach the pressure relief on the oil pump all the time as I spin the motor well past 6000 rpm for extended periods. My understanding (that could be very wrong) was that the pressure relief valve in/with the oil pump operates independently of the bypass valve. The bypass valve, I believe, opens when there is a pressure differential between what is coming into the filter versus what is going out. It is the differential that determines the opening of the valve, not the pressure level. So it can be at 30 psi idle pressure or 80 psi blow off pressure but it will only open if the out put from the filter is 16 (or 11) psi below what goes in. I am open to being wrong, in which case I am even more apprehensive about switching filters as I clearly don't even know how the things work!
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Okay ...and up until that point 100% of its flow is going to the engine.
Absolutely correct!
Well, let me rephrase that for you. It's when the exact same flow is creating a differential in excess of the bypass (filter) rating. That is, 5 (choose a number) gpm in ..5 gpm out ..resultant PSID.
Absolutely correct!
Absolutely correct! Except change your perception to "16 (or 11) psi above what the engine sees downstream".
Here's the rub. The total flow to the engine will be identical (variable for oil pump output) up until your relief limit of your oil pump. At that point you don't know how much is shunted back to the suction side of the pump. A higher bypass valve setting on your filter would make your oil pump reach this relief limit earlier as it "can" create higher upstream pressure as the filter accumulates debris The current filter with the 11 psi bypass setting will have you reach your oil pumps relief setting 5 psi "later" ..so to speak. How this impacts flow in those circumstances is unknown. You don't know if that means a whole bunch ..or anything worth thinking about.
I'm of the belief (with "adaptive" data) that your typical PSID across a filter is around 2-4 PSID after warm up. This is different when the oil is cold ..naturally ..but I doubt (at least I hope) that you aren't winding your engine out to 6000 rpm with 50 weight oil when it's stone cold.
[ February 27, 2005, 01:01 PM: Message edited by: Gary Allan ]
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