Those of you running the high volume oil pump.

[Sleeper-6]

I think of it this way. If you have 40 Psi of oil pressure pushing on the faces of the gears in a standard size oil pump. It is going to require "X" amount of torque to turn the gears the faces against it. If you have the large high volume gears, the faces are going to be larger therefore increasing the surface area for the 40 psi to push against. More push on those faces means more torque required to turn those gears.

More Volume OR More pressure = More work

More work = Greater amount of torque input to accomplish it.

We use a positive displacement type pump so no matter what the required amount of oil is, the amount it moves is determined by engine RPM. What happens to the oil after the pump gears is up to your by-pass spring, bering clearences, ect. But the volume of oil moved will be increased with the bigger pump.

 

[Blazer406]

....... But the volume of oil moved will be increased with the bigger pump.

The volume of pressurized oil is the same..... the remaining oil is sent back to the pan.....

This unpressurized oil IMHO doesn't appreciably increase drag (relative to the std oil pump) on the engine.... until the volume of pressurized oil exceeds the volume that the smaller std volume pump can put out.

 

[Sleeper-6]

To my understanding the flow path is.......Pickup----->pump gears------>(bypass valve and engine oil galleys) . These are not a variable displacement pump. A larger volume pump will move a larger volume of oil reguardless of if it is needed or not.

Therefore the pump cavity and larger gears are pressurized with the greater voume of oil reguardless of what happens to the oil being dumped after the relief valve. That 40psi in the pump cavity is bring spread over the greater surface area of the high volume gears. All prior to the relief valve. The volume of the pressuized oil in the oil galleys IS the same, but the total amount ol oil moved by the pump is greater.

For example

Volume of oil pumped by standard pump cavity (10 gpm@40psi)= Oil galleys (7 gpm@40psi) + relief valve (3 gpm@1psi)

Volume of oil pumped by high volume pump cavity (20 gpm@40psi)= Oil galleys (7 gpm@40psi) + relief valve (13 gpm@1psi)

The amount of torque required to drive the pump gears is determined by the amount of work done inside the pump cavity prior to the relief valve.

 

[Blazer406]

The amount of torque required to drive the pump gears is determined by the amount of work done inside the pump cavity prior to the relief valve.

I agree.... my point is I don't think the drag is significantly more when you compare 3 gpm @ 1 psi (which may actually be .1 psi.... it is really speculation anyway) to 13 gpm at 1 psi..... when compared to 7 GPM at 40 psi.... I guess IMHO.... I figure the 7 gpm @ 40 psi.... might be 90% of the total HP lost from the oil pump.....the 3 or 13 GPM at the much lower pressure is minimal comparitively speaking......... maybe I'm wrong.... I'm not suggesting that is immeasureable.... just that it is insignificant.

 

[Sleeper-6]

you are correct there, those numbers are just made up for the example. My point is that I believe the work being done by the pump is represented by the flow and pressure inside the pump cavity (20gpm@40psi), reguardless of where it goes from there. You could bring the flow throught the galleys to 1gpm and send the other 19 through the bypass. The High-volume pump will still be moving 20gpm against 40psi of back pressure vs. the 10 of the standard pump.

 

[callmeebryan]

Well, changed my oil this morning, and used 20W-50 Valvoline VPI Racing oil. My hot idle oil pressure is still 10psi, however i did notice that the cruising pressure and WOT pressure increased by about 5-8 psi from my previous 15w-40 Rotella oil.

I ordered the high volume front cover w/ pump from full throttle. Hopefully this will help my oil pressure.

 

[callmeebryan]

I just had a thought.... is it possible that there is a restrictor at my oil pump?

My oil pressure sensor connected to a Brass T that comes right out of the oil pump.... this line feeds the turbo. Could it be possible that theres a restrictor, which obviously would affect the oil pressure reading at that spot? I am not sure where guys usually put oil restrictors on these cars.

 

[JDEstill]

A picture of your setup would help, but even so, the oil pressure sender (or tubing if a mechanical gauge) is measuring a pressure, not a flow. As such a restrictor wouldn't really affect the reading. Only if you are picking up the pressure downstream of a restrictor would your pressure reading be any different. Typically if someone were to add a restrictor to the turbo oil supply, that would be done up at the turbo rather than down at the engine, although the stock brass block does have a restrictor in the port to the turbo. But again that wouldn't affect what the sender sees. I doubt this is your issue.

John

 

[SHADOWII]

Does anyone remember...

"way back when", there was a test on oil wt. vs hp? I thought it was KB that did the test, but Who knows What I always remember is the end of the test results were a cost of 15hp w/no other change than the oils used. 10/30 vs 50wt=15hp.

 

[bison]

Id verify the regulator system is not stuck. I use a blue spring (70 psi) myself. The oil pressure always gets up to 70 psi at around 3400 and then climbs from there when hot. If you have a yellow spring or something else the pressure will be considerably lower. Additionally the spring could be shimmed for more pressure. Oil pressure at idle means nothing. You want about 12psi per thousand rpm under load. I run standard gears in all the stock blocks i do. Never saw a need to go with taller gears when the oil pressure is hitting the regulated limit at 3400 or lower rpm when hot. Bypass oil is sent through the engine, not back to the pan. This is not good since the oil will be unfiltered and circulating through engine. If the oil was sent back to the pan and easily regulated then i would run taller gears. But with the stock configuration oil pump i dont think its needed at all.

 

[gnxtc2]

If your motor has tight clearances, you MUST keep the motor oil clean. There is a greater chance of the bearings getting scuffed if dirt gets into the engine.

Bigger clearances are more forgiving but need more VOLUME. More volume also keeps the bearing cooler.

Set up clearances on how you are going to use the car: daily driver, street/strip, race.

Picture this....the crank is sitting in the mains with bearings and caps in place. A film of oil is around the crank and bearings. The crank is surrounded by a film of oil. The oil is the cushion for the crank in coming in contact with the bearings. A strand of hair is .003. Now cut that strand in half, that's your oil cushion.

I was talking with Kenny D. and he has ran motors with .005 clearance with no problems.

Too much pressure is a bad thing. Once the oil cavitates, it's all over.

Look at a stock crank, 1 & 4 Mains are feeding only one rod journal each. 2 & 3 are feeding 2 rod journals each. That why it's recommended that 2 & 3 oil feed be opened up for more volume, hence the requirement for the high volume pump.

Billy T.
gnxtc2@aol.com

 

[cpac]

blew a 9441 gasket into the lifter vally ,all the mush ended up in the heads,by passing the oil filter,makes me think why are we always changing our filters if the majority of the oil is not filtered

 

[Jerryl]

....... Look at a stock crank, 1 & 4 Mains are feeding only one rod journal each. 2 & 3 are feeding 2 rod journals each. That why it's recommended that 2 & 3 oil feed be opened up for more volume, hence the requirement for the high volume pump. ....

This is exactly what I asked from my engine builder.
Rods were set around 0.0018 - 21PSI hot @ idle, 10W30, HV, drilled mains.

IMHO, if you drill the main, get the HV pump.
If you leave it stock, run the stock pump.

Someone already stated it: You need flow and pressure.
Kind of like boost. Boost alone is nothing, you need flow as well.
It is the "balance" between the two that adds up to performance.
More flow at same pressure = what yo want.

Here is some history on this "never dying subject" .......
http://www.turbobuick.com/forums/general-turbo-buick-tech/192997-help-solve-myth.html

Callmebryan,
There may be a problem in the motor with the cam bearing as well.

PS
Here is one more "never dying debate" - Oil Coolers .
Since my car is a DD, I added the oil cooler. Picked up 2 PSI "Hot Idle"