LS1Silverado05

iTrader: (41)

Could someone please tell me how psi and volume correlates? What I am trying to figure out is..if you have good oil psi are you garunteed to be ok?..Or could you have good psi and poor volume? If volume increases does psi also?

3.4camaro

iTrader: (1)

The more pressure you have, the more gallons of oil per minute will be pumped through the system. Think like a water hose.

tim99ws6

iTrader: (31)

This is not nessecarily correct. If you were to bore out that water hose, would your PSi not decrease, but you would be theoretically be able to move more water through it, correct?

to the OP, I think what you are referring to is the "ported/blueprinted pumps" that alot of shops sell? If so, what they do is bore the oil pump out, check the gears on the pump, and then shim the spring on the pump that regulates the oil pressure. After the pump has been bored, you have a chance of running lower than stock oil Psi due to the porting. They just shim the pump spring back up to get it within spec. Also, having too much PSi can be detrimental.

professorls1ss

tim is right, its how tight or sloppy the clearances in the engine are, that control oil pressure, the tighter the passages in the engine and bearings, the higher the oil pressure. race engines are set up looser for less friction and they need high volume oil pumps and bigger oil pans to keep the oil flowing.

mrdragster1970

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We usually use high volume standard pressure. That's what I was taught.

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3.4camaro

iTrader: (1)

You are correct. However, gal/min is affected by cross section of the hypothetical pipe we are talking about, AND pressure running through it. Increase either of these, and the flow rate will increase as well.

Higher pressure will result in more flow.
Higher volume will result in more flow.

LittleV6

Or could you have good psi and poor volume?
Yes. Some people will see they have poor oil pressure and use high viscosity oils. Sure it gets the pressure up (thick oil has more resistance to flow), but it doesn't do anything for volume.

If volume increases does psi also?
Yes, if everything else stays the same. The only way to get more pressure would be to add more flow. An oil pump creates FLOW, not pressure. Resistance to flow causes pressure.

FASTFATBOY

iTrader: (23)

The rule I was taught is:

Pressure goes up, volume goes down

Volume goes up, pressure goes down.

Pretty much true for any liquid under pressure.


David

3.4camaro

iTrader: (1)

Why would MORE pressure move LESS oil? You aren't thinking about this correctly.

FASTFATBOY

iTrader: (23)

I learned this growing up in a hydraulic shop, to get pressure a restriction HAS to be put in front of the flow, lowering volume.

What happens to your water hose when you put your thumb over the end or put a sprayer on? It sprays further(pressure goes up) but not as much comes out, smaller stream(volume goes down) and vice versa.

Notice this fuel pump spec chart from Aeromotive, as pressure goes up, volume from the pump goes down, it is the same for any liquid under pressure


Any fluid pump has the same laws applied to it.

David

Alvin

iTrader: (2)

Look up pump effeciency curves.

making generic statements like "more pressure = less flow" can get you into trouble. The pump is going to have a specific head that it works best with and that is not the least pressure.

topend

the electric fuel pump uses an electric motor to power the fuel pump. U load any electric motor up it will slow down(=less pumping volume). Now the engine oil pump runs at engine speed. U put a bigger oil pump in your engine it will pump more oil thru the engine which will increase oil pressure.U put a smaller pump in your engine u will pump less volume therefore you will have less pressure.

FASTFATBOY

iTrader: (23)

The original question is how volume affects pressure and vice versa.


Doesnt matter what is pushing the fluid, if volume goes up, pressure goes down and vice versa.

I think of it this way...if the same pump were used in an engine 1 and you had .009 bearing clearance(LARGE!) you would have low pressure and LOTS of volume...it would almost freeflow.

In engine 2 same pump with bearing clearance of .0025(what it should be on a small block Chevy) it would restrict the flow(less volume) making more pressure.

David

Alvin

iTrader: (2)

Here you go, this is a first law of thermodynamics problem.

This will help

http://www.grc.nasa.gov/WWW/K-12/airplane/thermo1f.html

FASTFATBOY

iTrader: (23)

I just glanced at that, but that looks to deal with gases, gases compress. Liquids do not. So I dont see where that applies...but I may have missed the boat LOL.

Another example: WHy is it bad when you have high blood pressure? Because the volume of blood is not getting where it should. The veins are restricted.


David

Alvin

iTrader: (2)

You have to assume incompressible flow when dealing with that equation (and most others that don't involve high level math), it will work for gasses or liquid.

topend

Again an engine oil pump runs at engine speed. Therefore the pump will spin at engine speed it wont slow down like an electric motor under load .the pump will pump X amount of fluid at X rpm.U turn the pump faster u pump more fluid which in turn increases the pressure until it is bleed of by the pump pressure regulattor. We see pressure because there is a restriction to the volume of flow, the flow is the same.More flow more restriction=more pressure.

DTL

1. if you maintain the same pipe/tube/line size and increase pressure, you will get more volume of fuel.

2. if you maintain the same pressure and increase line/tube/pipe size, you will also get more volume of fuel.

eallanboggs

iTrader: (1)

The spring in the oil pump does not increase pressure. It is an overpressure regulator. If the pressure goes up high enough to overcome the spring tension the piston is moved and the exeess pressure it bled off. This could be due to a restriction on the oil galley or a dirt oil filter for example. Lack of maintenance or maybe an engine failure of some sort.

Mattsz28

iTrader: (1)

I always thought of it like when you put your thumb over the end of a hose to water something.

What your doing is decreasing the size of the exit right? So when the size of the exit decreases, and the flow to the exit remains the same, the pressure at the exit must increase, hence the spray. This does not mean that the "flow" is better. Ideally, for better "flow", which is how much actual (item) you are moving, you would want to make everything larger and still maintain the "pressure" needed without making the exit smaller. If you just increased the size of the "hose" then the pressure would drop because there is less resistance to the movement of the item through it. Alternatively, if you increase pressure, the flow (amout of item (which does not compress) moving through a confined space in a given time) MUST increase if the hose size stays the same. In a motor if you hog out the oil pump and shim the spring, you are allowing the motor to move MORE liquid (oil) through the same size area, which SHOULD increase the oil pressure. Right? So if oil pressure goes up in this manner (more flow into the same size area requires a higher pressure) then how is it detrimental? (all that for a question)