OT- Best way to pipe oil manifold

GregSY · Jul 16, 2020

I have a friendly argument going. This oil manifold is fed from single source, and all of the branches feeding Machines A-D are the same size.

Expert #1 says the best way to plumb this oil manifold is from one end only, let's use X. Using this method, each machine (A through D) will get a good and equal supply of oil.

Expert #2 says it's better to 'loop' plumb the supply from X and Y so that the manifold is more equally pressurized. This way, Machine D won't see less pressure than Machine A when you feed oil in from X.

Expert #1 says if you plumb from both ends, the oil flow from X and Y will 'smash' into each other as opposing forces and create a situation where there will be good pressure but poor flow.

Expert #3 says if you single-feed the manifold from X, the oil will want to flow past ABC and will end up over-feeding D as it is the last branch. C will get more oil than B, but both will get less than D. A will get the least oil of all.

So who understands real-world flow results? Lots of theory, as you can see, but what matters is what really happens.

EmGo · Jul 16, 2020

Is it under pressure or just flowing ? Oil is incompressible, I believe ?

CarlBoyd · Jul 16, 2020

GregSY said:
I have a friendly argument going. This oil manifold is fed from single source, and all of the branches feeding Machines A-D are the same size.

Expert #1 says the best way to plumb this oil manifold is from one end only, let's use X. Using this method, each machine (A through D) will get a good and equal supply of oil.

Expert #2 says it's better to 'loop' plumb the supply from X and Y so that the manifold is more equally pressurized. This way, Machine D won't see less pressure than Machine A when you feed oil in from X.

Expert #1 says if you plumb from both ends, the oil flow from X and Y will 'smash' into each other as opposing forces and create a situation where there will be good pressure but poor flow.

Expert #3 says if you single-feed the manifold from X, the oil will want to flow past ABC and will end up over-feeding D as it is the last branch. C will get more oil than B, but both will get less than D. A will get the least oil of all.

So who understands real-world flow results? Lots of theory, as you can see, but what matters is what really happens.

View attachment 294271

If the manifold is significantly bigger than the most restrictive point in any of the down stream ports it really doesn't matter from a practical perspective.
IF that's not the case feeding from both ends is a good idea.

Expert #3 is wrong, as in free energy wrong.

Expert #1 also reasons incorrectly. flow to the 4 ports is dependent on pressure, if you have good pressure the oil flow, it doesn't matter if 1 oil has smashed into another.

CarlBoyd

GregSY · Jul 16, 2020

There is flow as the machines 'consume' oil.

Carl, I agree with every point you made.

DDoug · Jul 16, 2020

Bijur and others have long since penciled this problem out.....

garyhlucas · Jul 16, 2020

Done tons of manifolds fed from one end for feeding membrane cartridges and measured the pressure differences on 6 pipes using an extremely accurate pressure gauge. As long as the manifold cross section is significantly larger than the total cross section of the six pipes say double, pressure differences measured with the same gauge was less than 0.01 psi. Flow differences would thus be equally small.

Phil in Montana · Jul 16, 2020

All the manifolds I have made were feed on one end only but, I had flow control valves at every tap to bal. the flow...Phil

dian · Jul 17, 2020

as long as there is flow, there will be pressure loss in the manifold proportional to length. d will see higher pressure than a if fed from the right side. the question is if it matters.

gustafson · Jul 17, 2020

If the supply hose is the same size as the 4 distribution hoses, you will see progressive pressure drop and perhaps diminishing supply to the most distant machine.
IF the supply hose is large enough to minimize pressure drop to the smaller distribution hoses, then it will be fine

I assume in one shot systems the orifices are designed to equalize pressure and prevent this effect

Glock34 · Jul 23, 2020

Pressure is equal everywhere in a system as long as you have enough volume to maintain the pressure you are looking for. Therefore, if you are able to maintain pressure with a single feed line, a second would not change anything, and turbulence from the second input "smashing" into the first would not exist if they both came from the same source, or at least were the same pressure.

GregSY · Jul 23, 2020

"as you have enough volume to maintain the pressure"

That's always the 'easier said than done' part of the equation. GaryLucas's statement says a bunch about this whole issue.....which is that the manifold volume is often not large enough. In cases when the manifold volume is smaller than you'd like, the last branch tends to suffer as it's furthest from the source of pressure. Or maybe you see dissimilarities in pressure from branch to branch, wherever it occurs. The double feed helps alleviate that, IMO.

dian · Jul 24, 2020

looking at fuel manifolds people have been trying all kinds of multiple feeds (e.g. ls engines) and it never made a difference to single feed as far as i know. but then again it depends on what magnitude of the deviation would matter. dont forget flow is related to pressure in second power.

of course air manifolds are different and much more interesting/involved.

GregSY · Jul 24, 2020

In a fuel system (electronic fuel injection) that is well designed, it will have a 'loop' type plumbing as opposed to a single-feed. You can see this on many 'race' cars etc.

You comment is interesting....why is air different and more involved than liquid?

dian · Jul 24, 2020

because it compresses, i guess. all ls engines have a "dead end system" originally. i first thought it was stupid and how you get vapour lock, but its working on millions of them.

Doozer · Jul 24, 2020

digger doug said:
Bijur and others have long since penciled this problem out.....

I was thinking exactly the same thing.
Why re-invent the wheel?

-D

GregSY · Jul 24, 2020

Because it's not a Bijur type system and doesn't share the same demands or constraints.

On LS engines...and many OEM designed fuel systems...they are driven by cost and space as much as anything.

Go look at a 'race' car and you'll see loop systems in many cases.

Doozer · Jul 24, 2020

Maybe related, maybe not, but
making reference to the Bijur system
they were used in automotive chassis lubrication systems
before they were applied to machine tools.
They have those restrictors, or back-pressure check valves
to meter the oil, with essentially creates backpressure
on the back side and meters flow coming out the front.
To scale it up, I have done things like use spring loaded
check valves to essentially create the same concept.
You can get check valves up pretty big to any size,
and depending on how picky you are, if they have the
same spring and same pop-off pressure, they will meter
the same amount. If you want different amounts of flow
I guess you have to experiment with different springs
or adding a valve or restriction down the line.
What I am saying, is just scale up the Bijur metering
concept with larger components to suit your flow needs.

---D

GregSY · Jul 26, 2020

This discussion started around the oil system of a V8 engine....so the ability to add check valves or play too many games is very limited....there is simply no room.

This is a small block Chrysler engine in particular. These engines oil the mains off the right side lifter galley, and the mains in turn oil the rods. In this engine, the rocker arms are oiled off the #2 and #4 cam bearings, which get their oil from the mains as well.

The entire left side lifter galley is fed off the #1 main feed.

The #5 main is fed all by itself so we can consider it not part of this discussion.

When there is an oil related failure, it is most often the rods fed off the #4 main.

A number of experts, over many years, have the opinion that the #4 main oil passage is 'too close' to the point of entry and the oil 'rushes past' it on it's way to the other mains. That, of course, sounds like bullshit to me. I am much more inclined to believe that the #4 rods fail because the passage is being overworked...it has to feed the main, the rods, the cam, and the rocker arms.

So anyway, that was the point of my first post. My theory was, and is, the feed the right galley from both ends. Not because oil is rushing past #4 but just as a way of stabilizing the oil pressure and preventing any deficits. I'm also doing a number of other modifications but the 'loop' feed was where my question lay.

EPAIII · Jul 26, 2020

So, just what was the final count on those deck chairs just before the waves started to wash then off the decks?

GregSY said:
I have a friendly argument going. This oil manifold is fed from single source, and all of the branches feeding Machines A-D are the same size.

Expert #1 says the best way to plumb this oil manifold is from one end only, let's use X. Using this method, each machine (A through D) will get a good and equal supply of oil.

Expert #2 says it's better to 'loop' plumb the supply from X and Y so that the manifold is more equally pressurized. This way, Machine D won't see less pressure than Machine A when you feed oil in from X.

Expert #1 says if you plumb from both ends, the oil flow from X and Y will 'smash' into each other as opposing forces and create a situation where there will be good pressure but poor flow.

Expert #3 says if you single-feed the manifold from X, the oil will want to flow past ABC and will end up over-feeding D as it is the last branch. C will get more oil than B, but both will get less than D. A will get the least oil of all.

So who understands real-world flow results? Lots of theory, as you can see, but what matters is what really happens.

View attachment 294271

GregSY · Jul 26, 2020

Huh???????

OT- Best way to pipe oil manifold

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