High Pressure Or High Capacity Oil Pump Pinto

[Guest Brokey12]

Hi I have a standard pump on my pinto at the moment now have a race cam and pulley along with 40s would it be worth upgrading the oil pump ? If yes what type I see there high pressure and high capacity

[Dave R]

if you have good pressure when hot i wouldnt bother....

 

if you dont, then it may make it last a little longer......

i have a good secondhand hi flow hi pressure if you can wait a few weeks

 

dave

[Andi]

I had high pressure with fr32 cam. After a while the pinto leaked like a good un.

Since renewing with a standard it has been oil leak free for a few years.

 

Andi

[Guest Brokey12]

I'm thinking of going high capacity , It was fine before but now the engines out for a refurb I think it may be worth doing for piece of mind as I have a alloy sump to go on at the same time

[cb750]

It's recommended to change the small drive shaft at the same time, particularly if you go to high pressure pump. They are a bit weak and have been known to shear off. A high pressure pump shouldn't cause any more leaks as the pressure is in the rotating parts or the filter system, any oil seals or gaskets should just "see" oil throw?

[speedtripledan]

My tuned pinto had standard pump with no issues. And i thrashed it

[Snapperpaul]

8 psi per 1000 rpm recommended

I fit high capacity high pressure as standard

why not? Their cheap and you get more protection.

The one exception was a Cosworth rod engine when I fitted a Cosworth spray bar to an RS2000 pick up, then fitted Cosworth oil pump top plate to a Pinto high pressure pump cheaper than a Cosworth 2wd pump ( same pump as Pinto just a different top plate) by £100

[richardm6994]

I'll hold my hands up here and be honest....I've never truely understood why you get 'high-pressure' or 'high-capacity' pumps....surely they are pretty much one of the same?

 

Increase pump's mass flow rate (capacity).....i.e. try and force more oil through the engine's orifices....this surely increases oil pressure within the engine?

 

on the flip side;

 

Increase oil pressure........equals a greater mass flow rate (capacity) in order to achieve the increased pressure (how else are you going to generate greater psi other than to cram more oil through the orifices).

Edited September 18, 2014 by steamer

[Guest mower man]

+1 for high capacity if the engine build / crank /bearings are good no probs ,but niether will fix a fubared engine on its own!!!! mowerman

[Snapperpaul]

The high pressure pumps have a stronger spring so the release valve opens later = more pressure in the system

High capacity, some recon this is better than high pressure, so you flow more oil through the bearings

The Pinto high capacity pump has a thicker top plate which is not flat on the inside to accommodate a larger (taller) pump rotor

Your crank and any other rotating shaft effectively float on oil, the faster it rotates the more oil is thrown out necessitating more oil.

There is a balance between pressure and flow, the relief valve caps pressure to 55psi ( for high pressure pump) and at high revs more oil thrown out needs bigger capacity

[richardm6994]

"The high pressure pumps have a stronger spring so the release valve opens later = more pressure in the system"

 

This is where my head gets puzzled......you can't compress oil so surely the only way there can be more pressure in the system / pump is for the mass flow rate to of increased?

 

"High capacity, some recon this is better than high pressure, so you flow more oil through the bearings"

 

But but when increasing flow through a fixed orifice there needs to be an increase in pressure up-stream?

 

 

As mass flow-rate of oil increases through the engine, the pressure drop increases and thus you need morre pressure to create a higher mass flow rate....

 

my head hurts.....going for a lie down

Edited September 18, 2014 by steamer

[Snapperpaul]

Think of it as force and resistance

The pressure is how much force it takes to push the oil through the system

Smaller bearing gaps = more pressure for the same force

Heat the oil and it becomes more fluid = less pressure for the same force, this I agree is a bit counterintuitive as my physics says the oil wants to expand as the molecules push harder against each other

[Snapperpaul]

Not sure I answered you question

I'm not sure of my own answer

Edited September 19, 2014 by Snapperpaul

[Dave R]

i believe the high flow and high pressure is just refering to the pump, not the complete system (engine)

 

i think with a gear pump, the pump curve is a fairly straight line on the graph, so flow relates to rpm, and as snapper says the high flow pump is taller, so does give a higher flow into a given system for the same rpm

 

the relief valve is set higher, than standard, yet it will only reach this when given cold oil, and an engine whose bearings are tight enough not to relive more pressure than you are generating for a given rpm

 

basically if you have an engine thats not on its last legs the standard pump should be more than adequate

 

 

 

thats how i understand it....

[richardm6994]

The penny is starting to drop now....

 

With 'high pressure' referring only to the relief valve in the pump; during normal use it isn't really any different to a standard pump.....and the only time you could see a benefit / greater oil pressures (on a new/tight engine) is at high rpm or cold oil.

 

With 'high capacity' pumps, during normal use you are physically pumping more oil around the engine than the standard pump....so at lower / mid engine rpm's you'd see an increase in oil psi over standard (due to the increased flow rate) however max oil psi would still be the same as a standard pump because the relief valve is the same ( both pumps have the same max psi.....it's just high capacity would probably hit max psi at lower rpm than a std pump would due to it's increased flow rate)

 

Therefore 'high pressure and high capacity' must be no different to 'high capacity', except at higher rpm and cold oil where the max psi has been increased due to stronger relief valve.

 

Thanks guys....I've always wondered and now I know

Edited September 19, 2014 by steamer