When an orifice is needed & when it is not (long)

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All,

Overall this is a question, but I am throwing my logic/understanding in here as well. I am still trying to be sure of myself before I go forward in making my own bypass setup.

Some general facts:

1. There is pressure drop across the filter and other restrictions in the oiling system, even with a positive displacement pump. There is some misguided logic on this BB that I have seen saying that there is none. Positive displacement pumps have a linear relationship between flow and pump RPM. However, pressure at the pump outlet is dictated by the system's restrictions (and the restrictions typically fluctuate with flow rate). However, there is pressure drop on both sides of a filter, as well as across any other obstacles, whether it be a bend, an orifice, etc. Flow rate is the only thing that is constant through the system.

2. In terms of filter performance and safety for the filter media, differential pressure is all that matters. Assuming the outer case was strong enough, the filter media could handle 1,000 psi (or any pressure), assuming the differential pressure was within the correct amount.

3. In a parallel system, the fluid is going to seek the path of least resistance. The pressure required to pump through all of the restrictions combined in parallel is always less than the lowest restriction by itself.


Given all this, I have no question that if I decide to build a single remote system where oil is supplied from the oil pressure sensor and dumped back into the sump or valve cover, I WILL need a properly-sized orifice to restrict flow, because the differential pressure would quite nearly be equal to the absolute pressure read at the pressure sensor. This would be enough to damage the filter, or at least make me severely worried about it. No questions here on what to do...


However for a dual remote system (i.e. one full full, and one bypass filter, connected in parallel), I am seeing conflicting views on the matter. Here's my logic:

1. The filters are in parallel, with connected flow paths before and after each filter. The pressure drop across both of these in this configuration should be slightly lower than the pressure drop across the full flow filter alone. Because the differential pressure is dictated overwhelmingly by the full flow filter, the differential pressure is quite low. This does D.P. not pose a risk to either filter, so I do not see a need for an orifice for the bypass filter.

It seems to me the ONLY risk by not using an orifice is simply that the bypass filter could have very little flow through it, rendering the system marginally better at filtering than the full flow filter on its own.

However, looking at some of Amsoil's dual remote mounts, there is an orifice in the picture, which I can only assume is for the bypass filter. However, I have seen quotes on this BB in a search saying that an engineer at Amsoil says an orifice is not needed on the dual remote systems. Which one is it then?

I feel that my logic is sound, but I am smart enough to second guess myself when "the name" in bypass technology might do it differently.


I welcome input from those that know what they're talking about, but please don't muddy the waters with inaccurate information, I really am trying to make progress in my understanding here.

Thank you!!
 
Originally Posted By: ryaneirich
All,



Given all this, I have no question that if I decide to build a single remote system where oil is supplied from the oil pressure sensor and dumped back into the sump or valve cover, I WILL need a properly-sized orifice to restrict flow, because the differential pressure would quite nearly be equal to the absolute pressure read at the pressure sensor. This would be enough to damage the filter, or at least make me severely worried about it. No questions here on what to do...


I think the real reason you need an orifice is not to protect the filter from differential pressure- the filter's own internal bypass valve will do that just fine. The reason you need an orifice in this kind of system is because many engines can pump a huge volume of oil out the pressure sender port. Without some restriction to maintain pressure in the oil galleries, most of the oil delivered by the oil pump would bypass the relatively tight bearing clearances, squirters, rocker feeds, lifters, etc. and go right out the sender port, to the remote filter, through its bypass valve, and back into the pan. Which would leave the whirly and slidey bits inside the engine grossly under-oiled.
 
FWIW: my thoughts.

If you start tapping off and putting it back in through a valve cover you need an orifice because too much will flow through the bypass starving the engine of oil.

The bypass filter will flow very little compared to the full flow filter. But since the oil is pumped many times per hour it will eventually become very clean.

However.. many engines make it to 300000 or more miles with just a full flow. You add quite abit of complexity and fail points with a remote or bypass setup.
In the engines that fail "early" would "cleaner" oil have made them last longer?

So my question would be.. what is your goal, or target of putting all this money/work into your car? Will it even make it even last any longer.. usually the answer is no.
 
I am doing this to not use so much oil as a consumer (i.e. to be more green), and also I'm an engineer and the whole thing just interests me. I realize that at best I will break even on the cost, after I include all the hardware, the expensive filters, and the UOA's. At the end of the day, if you get enjoyment out of something then go for it.

But to comment on what you said, I don't believe that the bypass filter has the ability to flow too much oil, regardless of pressure. The orifice's only job is to protect the filter media from damage due to excessive differential pressure.
 
^^ Those guys nailed it. Think of the added filters as being in paralell with the engines flow paths. As you lower the filters restrictions more volume diverts thru them and less thru the motor.

If you were to put the paralell filters in Series with the motor now you've lessened that pressure drop so more for the engine.
 
...Although I could be wrong. As the other poster claimed, the bypass valve within the bypass filter would prevent damage to its filter media if it had too much DP. I was not aware that the EaBP filters had an internal bypass. Can anyone confirm or deny this?

Thanks!
 
Originally Posted By: Kawiguy454
^^ Those guys nailed it. Think of the added filters as being in paralell with the engines flow paths. As you lower the filters restrictions more volume diverts thru them and less thru the motor.

If you were to put the paralell filters in Series with the motor now you've lessened that pressure drop so more for the engine.


I'm not sure if I understand what you're saying; it sounds like you're saying to put the full flow filter and the bypass filter in series? This would tremendously increase resistance. And either way, a bypass filter by design is not supposed to see full oil flow. It's only supposed to handle a fraction of the total volumetric flow.
 
I have run an Amsoil bypass setup on a car with a factory oil pressure gauge for tens of thousands of miles. I fed the bypass like most folks; using a tee off the oil pressure sensor and the return through a hole drilled in the oil filler cap. I also installed a shut off valve on the feed line going into the bypass filter. I did this for several reasons...I could warm the car up, drive it for XXXX miles, pull into a gas station with the engine and oil at equilibrium temperature, note the oil pressure, shut the valve, and note the oil pressure again. I could note the oil pressure while driving, pull off the road, shut the valve to remove the bypass from the oil circuit, and pull back onto the road and drive again, noting the oil pressure. Maybe 3 psi difference. If I wanted to show off to my buddies, I could close the shut off and change the bypass filter with the engine running.

I'm not running the Amsoil bypass anymore; I went to a Kleen-Oil bypass...then I went to an NTZ bypass filter...then I went to a Puradyn bypass filter...then back to an NTZ...I'm currently fabricating brackets and going to reinstall my Puradyn together with an NTZ combined with a centrifuge; and then, I may NEVER change my oil again.

My point to you sir, is that those who get all worried and wrapped up in series vs parallel vs differential pressure vs 1000 psi vs the bogeyman starving their engine of oil haven't ever done it. The size of the feed line to the bypass IS the restriction. Bypass filter manufacturers have their own design engineers and they're not going to risk lawsuits, destroyed reputations, bad publicity, etc., if some engine blows to shrapnel and the failure can be traced to being their fault. Every bypass filter from every manufacturer I've ever seen either has a restriction orifice on the input side of the filter housing or simply a connection for an AN 4 line, which is 1/8" ID.

All you need to do is unscrew your full flow oil filter (or take one out of the box at a store) and physically measure the ID of the output hole. This diameter is 100% of your full flow capacity. Mine is 1/2", (Area is .1963) and it doesn't require calculus to realize that a 1/8" feed line (Area .0123) is less than 10% of this volume. If you wish to fabricate your own system, simply use size AN 4 as the supply line, and if you really can't sleep without an orifice, eBay sells ready made ones for turbo setups, simply search for "turbo oil feed restrictors."

Good Luck, have fun, and Welcome to BITOG!
 
I'm sorry, I realize that I did NOT answer or even address your questions. The answers you seek regarding a restrictor needed or not for a dual remote system I do not know. I am an Amsoil customer and user, but I doubt that their technical services department would be very helpful providing general information for someone wanting to fabricate their own system; obviously, they are in business to sell THEIR systems.

There ARE a few things I do know that may interest you; first off, as I alluded to above, restrictor orifices are inexpensively commercially available, here is one on eBay with interchangeable restrictor sizes: http://www.ebay.com/itm/Vibrant-Oil-Restrictor-Fitting-Kit-4-AN-x-1-8-NPT-/122079407829

Secondly, I have a single Amsoil bypass filter adapter I am no longer using. If you would be interested, I would be happy to sell it for slightly less than 1/2 of its new cost. Feel free to PM me if you so choose.

Thirdly, I have a post in which I measured actual oil flow using a 1/8 (AN 4) line, unrestricted, using 5W30, engine fully warmed up and motor revved to approximately 2000 rpm to simulate highway cruising. This is with an NTZ filter which has a 1/8" sized input: http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4101491/Re:_Change_filter_on_it's_own_#Post4101491

The miscalculation I made on this post was that my total output size was 3/4". It is 1/2"; regardless, I'm still at less than 10% of total flow, and my dashboard oil pressure gauge drops only about 3 psi at highway speed running the bypass.

Again, good luck!
 
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