2psi differential ?????

[oilforfun]

Hi,
On several occasions I have heard mentioned " 2 psi differential" when refering to a permacool sandwich adaptor.

What is this? I am assuming that it has to do with the flow thru the bypass filter. But how does it work.

For example, if the oil pressure coming thru the pan pickup to the full flow and the sandwich adaptor is say 50psi. Than what does the 2 psi diferential do?
Thank you,
Oilforfun

 

[Gary Allan]

oilforfun (OFF

)

(pardon me if you know all of this - but I don't know your level of understanding here - so bear with me)
For a flow you must have a differential of pressure. This is required for all flow. For example your 50 lbs of pressure is the differential between the pump output and atmospheric pressure (PSIGauge). Through a given opening, there would be a certain flow rate based on that differential. Now let's move to a pressurized environment. How can a 50 psi source flow into a 50 psi environment? It can't. So if you have a 1" supply line ..and tap off of it with another line ..take a longer trip and return to the same 1" line ..you're gonna get NO FLOW through the longer leg. There's no reason for it to make the trip for the simple economy of taking the path of least resistance ..in this case NO resistance* (inconsequenctial qualification*).

SO ..you introduce an engineered restriction to the normal flow path. This will create either a pressure drop below/beyond the restriction ..or, in the case of our oil pumps flow, a pressure elevation upstream of it. This pressure difference (or pressure differential) will compell flow, at whatever rate it may work out to, to the alternate pathway.

The Permacool poppet typically works out to a 2 PSIDifferental. You get whatever flow 2psi produces through the bypass filter. As the oil thins, the spring in the relief of the Permacool closes to maintain that 2psi differential. It will modulate depending on the visc/flow rate of the oil.

 

[oilforfun]

Hi,
Thanks for the explanation. If I understand what your saying, by using a permacool sandwich adaptor the pressure thru our Ralph Motorguards will be 2 psi.

That 2 psi is shunted off the primary full flow feed. Does that reduce the primary full flow feed by 2 psi?

For example, after installation will we see a 2 psi reduction in oil pressure as measured from the sending unit?

Or are you saying that if the primary full flow pressure is 50 psi that the engineered restriction reduces that by 2 psi? Which would result in 48 psi to the primary full flow (reduced from 50 psi)and that the bypass is alloted 50 psi, resulting in flow thru the unit at 50 psi.

Does that reduce overall PSI? Or does the return from the filter negate the 2psi loss system wide?

At how many psi does the sandwich adaptor bypass? For example when the engine is cold and the oil is thick or if the filter becomes obstructed. While bypassing for the aforementioned reasons does the adaptor shunt the psi into the full flow or is it a complete bypass? Bypassing both the full flow and bypass filters.

What would happen if the poppet valve were to malfunction? Say that it got stuck open or closed. Or malfunction inbetween. What would be the result? Would the engine starve for oil?

Thank you very much for your help,
Oilforfun

 

[Gary Allan]

Whoa! You're rapid fire there oilforfun!!

How can I say this here ... There can be a chicken and egg deal going on that ..hmmmm..

Let's just start in "space normal" status..

quote:

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That 2 psi is shunted off the primary full flow feed. Does that reduce the primary full flow feed by 2 psi?

---

No. There is a 2psi elevation on the engine side of the Permacool adapter. The FLOW splits into whatever the flow sees in comparative resistance from the poppet and the bypass filter. The total flow remains the same. The split of the flow may be 99:1, 90:10, 60:40 ..whatever. That is, what's 50psi at the sender (typical location) is 52psi at the engine side of the Permacool/bypass filter. The 2psi is the resultant pressure elevation from oil having to squeeze through the resistance of the poppet and the bypass filter. You're effectively seeing the increase in velocity through the poppet expressed in pressure elevation.

quote:

---

For example, after installation will we see a 2 psi reduction in oil pressure as measured from the sending unit?

---

No. Not unless flow is altered. This can only happen if you reach the pressure relief of the oil pump.

What you're missing (and most of have for most of our lives) is the nature of "flow dictated" pressures. We're all used to pressure/resistance dictated flows in our water faucet and whatnot (electricity, etc.). There, loss of pressure is loss of flow ..and increase in resistance is a loss of flow. This doesn't work that way ..at least normally.

FLOW is in command ..and everything else is altered to make the equations work. The only time flow is altered is when the pressure relief setting of the oil pump is reached. Then the circuit resembles (more or less) the hose and faucet deal where pressure/resistance alters flow.

quote:

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What would happen if the poppet valve were to malfunction?

---

It's a very simple spring and ball setup. It's very reliable. I can't think of a plausible manner that it can fail. I've tried defeating it with aviation Permatex and various sealants ..I've tried to stretch the spring out and that only resulted in the lead sinker that holds the assembly in place getting pushed out. It's pretty much a fail-safe system

As far as the construction/design of the Permacool adapter..it's merely a wall that the oil has to travel around to get to the other side (the big outlet port on the engine side AND the big inlet port on the filter side). You put a major obstacle in the main detour around the wall (the bypass filter) ..so the emergency escape hatch get opened (the poppet) to allow flow to the other side of "the wall".

Note the poppet @ 3 o'clock. This is the engine side of the Permacool sandwich (also note the crusties that my sealant attempts left).

The oil tries to leave by the outlet port on the lower recess there. It hits the virtual dead end of the bypass filter. The poppet relieves the flow to the otherside (mirror image).

 

[oilforfun]

Hi,
Thank you very much for taking the time to explain this subject to us flow challenged people.
Its been a great help.
Thanks again,
Oilforfun

 

[Olaf]

Mind if I horn in here with a related question?

I'm puzzling over a bypass filter for my Cummins. For the supply line, I 've decided to tap into the test port on the filter head, right next to the line that goes out to the turbocharger; I assume that oil coming out of the two places is at the same pressure. So, the question is this: If oil coming from the test port meets resistance in the bypass system, will it basically get "backed up," and either become static or flow back to where it came from and end up going into the turbo (instead of through the bypass filter)? I'm planning to tap the outflow into a fitting in the oil fill cap. I assume there's some pressure in there, but don't know how much. Any of this make sense?

 

[Gary Allan]

If I catch your drift here, Olaf ..you're not going to see any issues there. The pressure should be pushing equally on both. I doubt you could overload the supply (as in drawing too much oil through the bypass and lowering pressure) ..and that would be your only concern. The only way oil could back flow would be when you turn off the key.

Look at it this way, the bypass filter is just an extension of the plug in the test port ..with a controlled leak that drains where you want it to.

 

[Olaf]

Great. Thanks, Gary!

 

[RalphPWood]

One of my Motor Guard customers came by and showed me his fill cap with a fitting in it that he got from Oilguard. It was a high quality thing. I used a saddle clamp to return the oil to the turbo return tube on a new Dodge Cummins. Similar to the saddle valve you use to tap into a water line for a water filter. I prefer to return the oil down lower so that the filter will drain good at shut down. The hook up for the bypass filter is the same as the oil for the turbo. The turbo gets it's oil from the filter mount and returns it to a low pressure point. I had some Perma-Cool universal 189 adapters set up for the Dodge Cummins. I took the center piece to a machine shop and had them make the center pieces with 1"-16 threads and left the 3/4"-36 threads so that a shorter filter could be used. The stock full flow filter was too long. It didn't go over too well because people thought the engine would starve for oil if they didn't use the stock filter size threads. I didn't waste time having more made. I prefer the sandwich adapters because the filter will work better with less pressure on the element. The oil soaks thru at it's own pace. I think the last Dodge Cummins I did have a metric test plug. The 1/8" didn't start so I used a 1/8" BSPT adapter.
I got started using the Frantz two port sandwich adapters. The Frantz worked very well for me but you can always expect to get someone that notices the oil pressure isn't quite as high as it was. The Frantz didn't have the relief valve. You get that with teeing off at the oil pressure switch also. The advantage to the Perma-Cool adapters is you can drill them to help the relief valve or to keep the internal engine relief valve from opening too much. If you install a Perma-Cool sandwich adapter on most GM engines the relief valve in the filter mount will stay open. The only oil the full flow filter will get is what has already been filtered by the bypass filter. That wouldn't be a problem for me. I would drill the adapter or add a relief valve. If you drill the relief too large the resistance won't be enough to heat up the bypass filter unless it is a bypass filter that has no depth. I have some unusual customers. Some are installing a Perma-Cool remote mount with four ports. They are using two of the ports to hook up the Motor Guards. They are using the pressure drop thru the remote mounted full flow filter to feed the Motor Guards. What works in Southern California might not work up north.

Ralph

 

[oilforfun]

Hi,
Is it common to have to drill the sandwich adaptor on smaller engines? Say four or six cylinders. Or is it only on larger engines with higher oil demands?
Is it common to have to drill them at all?
Thanks,
Oilforfun

 

[oilforfun]

Hi,
How would we know that it needs to be drilled in the first place?
Thanks again,
Oilforfun

 

[Gary Allan]

If you have lower downstream pressure. That means that your oil pump is in internal relief. It's very rare that the poppet on the Permacool isn't enough to move the entire flow of oil that the pump provides through it.

 

[oilforfun]

Hi,
For us pressurly challenged, can you explain what "lower downstream pressure" is?

How would we detect it? Would it be indicated by a lower PSI reasding on our oil pressure gauge? Or some other way?

After installation of a Ralph Motorgaurd, how is it best to determine that the system is operating correctly? Like all newbies, we want to make sure that it is lubricating and filtering correctly.
Is there a procedure or checklist that we should go thru, after we install to verify correct operation? In regards to flow and filtering.

Thank you very much,
Oilforfun

 

[Gary Allan]

No one can say that you leave any stones unturned here, oilforfun

If you have a pressure gauge ..a real one..it's typically tapped just after the filter. Now anytime flow is truly reduced it will result in lower indicated pressure. This only happens when the oil pump is in relief. For this to happen you have to have a fairly high volume oil pump, relatively speaking. Otherwise, your cold oil pressure should be very close to the same as before the installation. Your hot oil pressure should be the same (assuming the same temps/rpms/etc.). So, you wouldn't necessarily drill a hole if you lost 5psi of cold oil pressure if your hot oil pressure was the same. You want to keep the "self regulating" nature of the poppet valve intact, otherwise you could have very limited flow through your bypass filter after full warm up.

If I only had an idiot light, I would rely on valve train noise (assuming that I didn't already have valve train noise) or like symptoms.

Again, it's a rare instance where you have to alter anything in the Permacool setup. Trust me, when I saw the size of that poppet port ..I really thought that Ralph was FOS and that there was no way that it could handle the full flow of oil to any engine. I was wrong. After I set up my before and after gauges ..and drilled holes and had things NOT work, I realized that he was right all along. That's why you don't see him think too much about it and how he appears to react so casually about these types of concerns. That is, most of them are unfounded.

[ November 27, 2005, 03:48 PM: Message edited by: Gary Allan ]