Changing the oil filter bypass pressure

[bison]

Bison.....he is talking about the oil FILTER bypass, not the regualtor spring. He wants to push more oil through the filter. There is a bypass spring in the filter adaptor that is completely separate to the "blue" spring REGULATOR. It is a little plunger you can see with the filter/cooler adaptor off. It is below the threaded spud that the filter/cooler adaptor screws onto. THAT is what he wants to "re-spring" Not the pressure regulator. I just remove the bypass valve (it's knocked in like a freeze plug) thread the hole, and install a pipe plug. You MUST use a filter with a bypass in it, or you WILL blow it apart!!! Been there, done that. I actually had one blow up in my face, once. I maybe a slow learner, but at least I LEARN. Never did THAT again. It blew oil EVERYWHERE!!! In my face, eyes, chest, wall, floor, inner fender, battery, ceiling, wall, wall and more on the ceiling. What a MESS! Thank God it happend on start up, and the oil wasn't HOT. That would have been ALOT worse. I didn't realize a PF-52 doesn't have a bypass valve.

I didnt realize what he was doing. I assumed he already blocked that off. Ive known of others who did the same thing you did too. At the track no less. Luckily it happened during the burnout.

 

[Sleeper-6]

Sorry, I haven't had a chance to work on it much further. I have the part numbers here somewhere, but it has been a while since I looked at them. Give me a few days to look it it again and I'll post the numbers up here.

 

[karolko]

that would be awesome.

I have a follow-up question for you guys. If you upgrade this bypass spring to 62.5lbs, no oil will be bypassed unless the oil pressure surpasses that. Now, are there any negative effects of running 70+ psi through a oil filter. I will be running a remote mounted filter that is much much larger than the 52, so should the extra volume and filter media surface area help the added volume of oil wanting to go through the filter?


Adrian

 

[karolko]

i am not too cetain where the oil bypass valve is. I have read that it is in the aluminum adapter for the oil cooler lines. what if you are not running the remote oil filter adapter, do you still have a bypass? Is there a bypass on the timing cover itself?

Photos maybe?

 

[Scott Atk]

That's a third bypass... for the oil cooler if it has blockage.

 

[karolko]

hmmm okay. i guess i will still have modification even though i do not have the oil cooler adapter.

 

[TurboBob]

any updates on this discussion?

The filter bypass is there in case the filter is plugged, or the oil is too thick to get thru it. But the oil flow and pressure changes with RPM and temperature.

There were a few guys blocking it, and using the biggie adapter. I need to search further.

But at idle, warm, lets assume normally the oil pressure is ~15 psi. this is measured after the filter so if the bypass is open then the pump is putting out 35 at idle. My guess is that the bypass may be opening at WOT when the oil flow demand exceeds the capacity of the filter, thus causing a pressure drop and opening the bypass.

Someone should put a pressure gauge before the filter and measure the drop. Does anyone have specs on the pressure drop of the various filters at different flows? And for that matter, how high does the flow rate get in a typical Buick V6? What is the theoretical maximum pumping capacity of the stock Buick oil pump?

Bob

 

[A2000RICH]

any updates on this discussion?

The filter bypass is there in case the filter is plugged, or the oil is too thick to get thru it. But the oil flow and pressure changes with RPM and temperature.

There were a few guys blocking it, and using the biggie adapter. I need to search further.

But at idle, warm, lets assume normally the oil pressure is ~15 psi. this is measured after the filter so if the bypass is open then the pump is putting out 35 at idle. My guess is that the bypass may be opening at WOT when the oil flow demand exceeds the capacity of the filter, thus causing a pressure drop and opening the bypass.

Someone should put a pressure gauge before the filter and measure the drop. Does anyone have specs on the pressure drop of the various filters at different flows? And for that matter, how high does the flow rate get in a typical Buick V6? What is the theoretical maximum pumping capacity of the stock Buick oil pump?

Bob

i actually started working on quantifying this just last week-------not so simple or straight forward-------just because the valve starts to crack at any given pressure it just means oil stars to bypass at a very small rate------one thing is certain------just because the valve starts to flow at a given pressure it takes a large increase to bypass a major portion of the oil especially given the path that it takes--------it would be highly unlikely that a filter would ever clog to the point that all the oil would ever be 100% bypassed--------i am working on a pair of flow meters and intend to graph this with different temp and viscosity oils..........RC

 

[earlbrown]

There's a lot of misconception about how that bypass circuit is laid out.

It's not a dump valve so a lot of math can't be accurate. The valve itself is a variable bleed not a quick dump valve (must like our wastegates)

The cracking pressure is not just the spring inside. It's a difference in pressure on the entrance to the filter housing (the square hole) and the final pressure port leading to the engine. The front side of the valve has oil pump output trying to push it down. The back side has a spring pushing on it PLUS the output pressure of the pump (what shows up on our oil pressure gauges). It's just like our fuel pressure regulators. They have a boost/vac on one side and a spring + fuel pressure on the other)

Let's say the cracking pressure on the bypass spring is exactly 20 pounds. Just to keep things simple lets say the bypass valve is like a light switch, it's either on or off. (just to keep things simpler)

In this example the pump is putting out 100psi and the oil pressure gauge is reading 85PSI at WOT. In that example the bypass valve is closed as there's only a 15psi delta on the valve.

Next we decided that an orange filter would look cool and a Fram was mounted that has extremely poor flow. The pump is putting out the same 100PSI and the filter is starving output side of the pump. Now the bypass valve has the same 100PSI on the front, the same 20# spring on the rear but it's lost pressure on the backside of the valve. Now the difference is pressure has exceeded 20# and the valve opens. (must the same as if the vac line blows off the AFPR on the top end. fuel pressure drops to 45 and KERBLAM).

Now we learned our lesson about Fram filters and we bought a biggie kit and put a Mobil1/PureOne/K&N, etc.. filter on there. Now we've got the same 100PSI on the front of the valve, the same 20# spring on the back and even MORE pressure on the backside of the valve due to the bigger filter that flows better. Since the filter flows more, the oil pressure gauge on the dash reads 95PSI now. Since the deltaT is 5 pounds the bypass valve isn't even thinking about opening.

Now we're getting cocky about our new badass filtering arrangement. Rather than use that thin expensive synthic oil we're going to run 90W115 gear dope. That thick stuff should protect the hell out of our engine.

Now the pumps, putting out 150PSI at WOT. None of that crap can get through our biggie filter and the backside of the valve doesn't get it's boost to help the spring out. The valve's wide open and the gear dope is oozing out the filter and the little bitty valve at a snail's pace. The timing set has an extra 100HP worth of parasitic losses and oil's in no hurry to get to all the bearings in time.

So the moral of the story is that the best thing to do for filtering is to make an efficient filter arrangement. If you insist on having restrictive filtering yet really feel the need to filter ever last drop of oil at any cost... then blocking the bypass is the way to go. Personally I'd rather leave it alone and set it up where it doesn't have to do anything.


Now here's the kicker. On all those examples I was using even numbers of pump pressure going into the filter.... The way the pressure relief valve works is to set the pressure coming OUT of the pump. Not the actual pump pressure.

What that means is if you have an 85# spring, that's not what the pump makes. The pump has to make as many PSI's as it takes to end up with that 85#s. In a perfect world it's only have to make 85. In real life, the pump has to overcome flow restrictions, sharp edges, mismatches shoulders, etc... So the more drag you give it the harder the pump has to load the engine and heat the oil.



I'm sure there's more and I'm sure my thoughts were a little out of order.....

...but I'm tired (and been playing with timing covers too much lately)

 

[TurboBob]

i actually started working on quantifying this just last week-------not so simple or straight forward-------just because the valve starts to crack at any given pressure it just means oil stars to bypass at a very small rate------one thing is certain------just because the valve starts to flow at a given pressure it takes a large increase to bypass a major portion of the oil especially given the path that it takes--------it would be highly unlikely that a filter would ever clog to the point that all the oil would ever be 100% bypassed--------i am working on a pair of flow meters and intend to graph this with different temp and viscosity oils..........RC

Could even quantify a few different oil filters as well (perhaps)

Bob

 

[Nick Micale]

...........So the moral of the story is that the best thing to do for filtering is to make an efficient filter arrangement. If you insist on having restrictive filtering yet really feel the need to filter ever last drop of oil at any cost... then blocking the bypass is the way to go. Personally I'd rather leave it alone and set it up where it doesn't have to do anything..............but I'm tired (and been playing with timing covers too much lately)

Just like many discussions here, there is no one-size-fits-all answer as first the conditions of use need to be defined. I do agree with Earl, leave the bypass valve alone.

Depending on the oil pressure, what the use will be - RPM range especially upper limits, HP and boost developed, weather temp range and many other variables can help determine what oil filter will work best for a given application.

Since I do have lots of experience [and mis-experience ] with race applications, including other makes, not just Buicks, and would like to address that area first.

I doubt that most street engines do not see over 7000 RPM, high boost and HP very often and have an engine costing in excess of $20K, so I will start here.

We MUST have sufficient, un-interupeted oil flow at all times. Most filters will not handle this properly because of the filter media. It is usually too "fine" [8-15 microns] to pass the volume of oil needed.

At high oil pressure like at cold start, the oil will be forced through at the weakest areas and the result is "tracking". So say they claim 400 sq" of filter area, how much of this is actually used? Usually these filters also have a bypass internally to compensate for this issue.

The race filters from Wix and Fram address this issue, but still may have an internal bypass valve, but a higher micron number. The K&N and Mobile I have great specs, but do not flow well for performance use. This is not just an opinion as I have opened MANY race filters and seen distorted and clogged filter media.

The best filter I have found and do use in the race application is the stainless steel mesh in a 40-45 micron which does NOT need or use a bypass as they do not "channel" or clog. My engine gained 5-10 PSI oil pressure over the entire RPM range.

To continue along the lines of what Earl posted, if you have the right oil and filter for your application, you do not need to worry about the small amount and time oil is bypassed.

For a street application, the very small micron media filter probably does more harm than good, since the very small particles do no harm.

Good oil FLOW is also needed to help cool the internal engine parts. About 30-40 percent of oil cooling is done be the oil, the rest by water/coolant.

 

[turbofabricator]

But....But......I SAW the Fram commercials on TV and all the top NASCAR teams run them in their racecars!!!! Say it isn't so...........

Awwwwww, now you're gonna tell me that Al Gore has been trying to scam us with global warming? You all are off your rockers! If it wasn't true, they couldn't say it in a commercial or on TV. I mean there are laws about false advertising............right?:biggrin:

 

[KL Mallender]

I can tell you that blocking the oil filter relief "WILL" force all the oil to go through the filter, right up untill the filter's internals collapse inward and block off it's outward flow , you will know when this happens when the filters sealing ring spews oil all over the place making for quite a mess and a fire hazzard in one fell swoop. The head pressure the stock pump is capable of is beyond what most filters can really safely handle.
For this to work you must increase the size of oil lines and filtration surface areas to deal with cold start-up problems, and I'm not just talking about below 68* degrees. You might now understand why professional racers warm their oil before running and take the precautions they do, big differences between production and racing needs and requirements, but is the only real way to truely "Filter" engine oil.


Kevin.

 

[blacksix]

So what's the short uncluttered answer to this question? At what approximate pressure does the oil bypass the filter, stock version? 10 psi? 20? 100? It doesn't seem reasonable to me that GM would like to bypass the filter anytime the engine goes past 4000 RPM (40 psi) . . .

And will that change when going to a remote system like the Turbo Saver?

 

[87GN_70GS]

So what's the short uncluttered answer to this question? At what approximate pressure does the oil bypass the filter, stock version? 10 psi? 20? 100? It doesn't seem reasonable to me that GM would like to bypass the filter anytime the engine goes past 4000 RPM (40 psi) . . .

And will that change when going to a remote system like the Turbo Saver?

The answer is 20 psi across the filter. It really has (almost) nothing to do with what you see on your oil pressure gauge.

If the filter is low restriction, there will be only a small pressure drop across it (a few psi). This is less than the bypass cracking pressure so the bypass stays closed and no oil is bypassed.

If the filter is highly restricted, the pressure drop across it will be more than bypass cracking, and oil will be bypassed.

 

[TurboBob]

The answer is 20 psi across the filter. It really has (almost) nothing to do with what you see on your oil pressure gauge.

If the filter is low restriction, there will be only a small pressure drop across it (a few psi). This is less than the bypass cracking pressure so the bypass stays closed and no oil is bypassed.

If the filter is highly restricted, the pressure drop across it will be more than bypass cracking, and oil will be bypassed.

Sounds about right, I talked to the Canton guys about the pressure drop on their filters and its really low, so the bypass will stay shut under all normal conditions.

The filter is a very nice piece, got it from Mark at TR Custom. Very happy with it.


Bob