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Vd=0.7854B2S, CR=Vd+Vc/Vc
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Discussion Starter · #1 ·
Fact or Fiction, Gospel or Myth?

The Small and Big block standard volume (stn vol.) hydraulic pumps are pretty much equal in cubic inch displacement per revolution (CIR)
Ether pump could be installed in a small block and the horse power requirement to oil the motor would be the same assuming equal efficiency.

When comparing the Big and Small block high volume (high vol.) versions of these two pumps the small block is the larger volume pump.
The Big Block high vol. pump falls smack in-between the small block stn and high vol. pumps.

The difference in horsepower required at 70 psi is negligible as compared to 50 psi, all else being equal.

Using the pump sizing formulas available to anyone in the “Fluid Data handbook” for engineers, and measuring the pumps in question, I calculated the following; assuming 100% efficiency:

Small block stn vol. 2.45 gpm at idle (400rpm) and 18.4 gpm at peak (3000rpm) Engine rpm is double pump rpm.
Small block high vol. 3.06 gpm at idle (400rpm) and 23.0 gpm at peak (3000rpm)
Big block stn vol. 2.41 gpm at idle (400rpm) and 18.0 gpm at peak (3000rpm)
Big block high vol. 2.765 gpm at idle (400rpm) and 20.7 gpm at peak (3000rpm)

Horsepower requirement for a Big block high vol. pump at 60 psi and 90% efficiency is 0.8 hp
A Small block high vol. hydraulic pump will pump out a 5 litre oil pan 4.6 times per minute at 6000 engine rpm.

Seams to me running a High vol. high pressure Big block pump in a small block is no big deal.

Has all the taboo talk about high vol. high pressure been misinformed speculative Voodoo?
 

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WFO
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In the past, SBC engines that were wet sump running high rpm used a BBC pump not for any difference in volume (pressure is regulated by the relief spring so is basically a non issue), but because the BBC pump had more teeth and so would be smoother and potentially prone to less spark scatter/deviation w/a side benefit of a larger pick up tube diameter.

Nowadays, there's no need to use a BBC pump- there are many perfectly adequate SBC pumps available w/as much volume as could be needed and w/larger diameter p/u tubes if desired.
 

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Fact or Fiction, Gospel or Myth?

The Small and Big block standard volume (stn vol.) hydraulic pumps are pretty much equal in cubic inch displacement per revolution (CIR)
Ether pump could be installed in a small block and the horse power requirement to oil the motor would be the same assuming equal efficiency.

When comparing the Big and Small block high volume (high vol.) versions of these two pumps the small block is the larger volume pump.
The Big Block high vol. pump falls smack in-between the small block stn and high vol. pumps.

The difference in horsepower required at 70 psi is negligible as compared to 50 psi, all else being equal.

Using the pump sizing formulas available to anyone in the “Fluid Data handbook” for engineers, and measuring the pumps in question, I calculated the following; assuming 100% efficiency:

Small block stn vol. 2.45 gpm at idle (400rpm) and 18.4 gpm at peak (3000rpm) Engine rpm is double pump rpm.
Small block high vol. 3.06 gpm at idle (400rpm) and 23.0 gpm at peak (3000rpm)
Big block stn vol. 2.41 gpm at idle (400rpm) and 18.0 gpm at peak (3000rpm)
Big block high vol. 2.765 gpm at idle (400rpm) and 20.7 gpm at peak (3000rpm)

Horsepower requirement for a Big block high vol. pump at 60 psi and 90% efficiency is 0.8 hp
A Small block high vol. hydraulic pump will pump out a 5 litre oil pan 4.6 times per minute at 6000 engine rpm.

Seams to me running a High vol. high pressure Big block pump in a small block is no big deal.

Has all the taboo talk about high vol. high pressure been misinformed speculative Voodoo?
You're taking a lot for granted in your calculations. Way to much for them to be of any real significance. You need to find or develop pump curves for each pump running the oil you use at your oil temp. Then you'll be able to make some legitimate judgements on pump comparisons.
 

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Vd=0.7854B2S, CR=Vd+Vc/Vc
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Discussion Starter · #4 ·
Show me the math

You're taking a lot for granted in your calculations. Way to much for them to be of any real significance. You need to find or develop pump curves for each pump running the oil you use at your oil temp. Then you'll be able to make some legitimate judgements on pump comparisons.
I find it odd that you would say i'm taking a lot for granted in my calculations.
Im' just comparing volumes to illustrate a point, to dispel some myths.
For example the idea that a big block high volume oil pump uses a lot of power, Or that it
could pump a pan dry.
Or that putting a high pressure spring in is wasting energy.
I thought it was interesting to find that a SBC-hv oil p/p is notably larger than the BBC-hv oil p/p

For you to say the math is not of any real significance, tells me you don't understand it.
Or maybe you do, If you have a formula that works better lets hear it.
If you have a easier simpler way to evaluate and compare the chev oil pump please share.
Please elaborate on your pump curve idea.
 

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I find it odd that you would say i'm taking a lot for granted in my calculations.
Im' just comparing volumes to illustrate a point, to dispel some myths.
For example the idea that a big block high volume oil pump uses a lot of power, Or that it
could pump a pan dry.
Or that putting a high pressure spring in is wasting energy.
I thought it was interesting to find that a SBC-hv oil p/p is notably larger than the BBC-hv oil p/p

For you to say the math is not of any real significance, tells me you don't understand it.
Or maybe you do, If you have a formula that works better lets hear it.
If you have a easier simpler way to evaluate and compare the chev oil pump please share.
Please elaborate on your pump curve idea.
Its not my "pump curve idea" its how pumps are secified for applications, and yes that's a part of my job. I sometimes do basic open and closed channel hydraulics for landfills. Your volume and power calculations are WAY off as they use assumptions that simply aren't true for your aplication.

I understand your proposed theory but in hopes of a simple answer you're over simplifying the question. What you're after is the power consumption and flow for the given pumps for a very specific fluid at a specific temerature with a specific amount of static and dynamic loss. All of those specifics are application dependant and vary from car to car. A pump curve for your fluid and temperature will get you in the ball park but you still need to figure dynamic head loss, which isn't so easy on an unknown oiling system.

The best way to make your comparison would be to simply run the engine on a dyno with each pump a number of times and plot pressure, power, and flow against rpm while maintaining the same temperatures. Id also use a dyno that allows you to hold at specific rpms in effort to get more accurate results.

You can then plot those results against a pump curve to get what they call a system curve, if you so desire.
 

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Vd=0.7854B2S, CR=Vd+Vc/Vc
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Discussion Starter · #6 ·
hydralics person has the dope

Your volume and power calculations are WAY off as they use assumptions that simply aren't true for your aplication.

Which formula was it that you used to proof my calculations WAY off?

you would never say i was way off as an assumption now would you?
 

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WFO
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What you're after is the power consumption and flow for the given pumps for a very specific fluid at a specific temerature with a specific amount of static and dynamic loss.
What "static losses" are you referring to? Static implies at rest; I fail to see how there are going to be losses that will affect an oil pump in operation- when the pump is not in operation.
 

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What "static losses" are you referring to? Static implies at rest; I fail to see how there are going to be losses that will affect an oil pump in operation- when the pump is not in operation.
static losses would be minimal, usually its the elevation change, in this case it would be less than 2' of pressure of the oil column usually its measures in ft of water or inches of mercury.

In hydraulics static losses are losses that occur no matter what the flow rate is, dynamic are dependent on the flow rate.
 

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Which formula was it that you used to proof my calculations WAY off?

you would never say i was way off as an assumption now would you?
The fact that you think the pumping volume is linear and that you would see anything close to 100% efficency shows me your WAY off. Also, you didn't mention any properties for the fluid your pumping, which will have a HUGE impact, even something as simple as switching from 5W-20 to 10W-30, hell even going from 120º to 220º with the exact same oil will have a HUGE impact.
 

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Vd=0.7854B2S, CR=Vd+Vc/Vc
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273 Posts
Discussion Starter · #10 ·
The fact that you think the pumping volume is linear and that
you would see anything close to 100% efficiency shows me your WAY off. Also, you
didn't mention any properties for the fluid your pumping, which will have a HUGE
impact, even something as simple as switching from 5W-20 to 10W-30, hell even going
from 120º to 220º with the exact same oil will have a HUGE impact.
True enough temperature and viscosity will have a huge impact; an impact on what?
I'll answer that one for you, an impact on a set of baseline calculations.
A simple base number can be elaborated on, referred back to, it will reduce confusion. anyone reading my numbers can multiply by 85% to get a truer flow rate.
If we're going to talk about efficiency I suppose it could be along the lines of which of the two pumps (SBC or BBC) is more so and why.

You brought up the topic of linearity in the pumps output, Now explain to us all how to factor that into the equation. Tell us why the pump is or is not linear in it's output.
 

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True enough temperature and viscosity will have a huge impact; an impact on what?
I'll answer that one for you, an impact on a set of baseline calculations.
A simple base number can be elaborated on, referred back to, it will reduce confusion. anyone reading my numbers can multiply by 85% to get a truer flow rate.
If we're going to talk about efficiency I suppose it could be along the lines of which of the two pumps (SBC or BBC) is more so and why.

You brought up the topic of linearity in the pumps output, Now explain to us all how to factor that into the equation. Tell us why the pump is or is not linear in it's output.
A "please" would be nice.

Also, pump efficiency is not a set number, it varies with pump use, pressure differential, and speed- for one given pump. NONE of this is as simple as you think it is.


And yes, you did a real simple displaced volume calculation that is essentially useless, just because you clicked a few buttons on your calculator does NOT mean your new number carries any significance.

FWIW, pump curves are NOT calculated, they are plotted from test data on a pump AFTER is has been built becase there are too many variables to calculate correctly. You can slightly fudge the curves if you know what you're doing when you modify pumps, but if you called up a pump manufacturer with your "flow calculations" they'd simply say "wtf?" cause its not even close.

BTW if a stock sbc oil pump is even 60% efficent at peak I'd be VERY surprised.
 

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Vd=0.7854B2S, CR=Vd+Vc/Vc
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Discussion Starter · #12 ·
A "please" would be nice.

Also, pump efficiency is not a set number, it varies with pump use, pressure differential, and speed- for one given pump. NONE of this is as simple as you think it is.


And yes, you did a real simple displaced volume calculation that is essentially useless, just because you clicked a few buttons on your calculator does NOT mean your new number carries any significance.

FWIW, pump curves are NOT calculated, they are plotted from test data on a pump AFTER is has been built becase there are too many variables to calculate correctly. You can slightly fudge the curves if you know what you're doing when you modify pumps, but if you called up a pump manufacturer with your "flow calculations" they'd simply say "wtf?" cause its not even close.

BTW if a stock sbc oil pump is even 60% efficent at peak I'd be VERY surprised.
So cubic inch displacement per revolution is "essentially useless”, the engineers at fluid power are idiots for suggesting that a hydraulic pump can be sized in this way.
Well i'm glad you brought this to mine and anybody reading this attention.
I should stop my investigation into the Chevy oil pump as i will surly be over whelmed by the complexity of the situation.
Thank you for your input on this thread
 

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WFO
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Putting aside for the moment talk of pump pressure curves and static losses due to barometric pressure changes
, it has been shown (to MY satisfaction at least) that a HV pump isn't needed in most SBC builds. Period.

As far as high pressure goes, excess pressure can aerate and heat the oil as well as cause pumping losses and generally is not wanted any more than (and possibly much less than) too much volume.

A standard volume pump w/a relief spring that will provide hot oil pressure of at least 15 psi at idle and peak at 65 psi or so will do just fine most of the time. Some prefer the old rule of thumb of 10 psi per 1000 rpm, which is also fine by me as long as the idle pressure is higher than 10 psi.

Some reasons to use a HV pump might be due to one or more of the following:
  • wider than usual oil clearances at the crank
  • mods like under piston oilers or spring oilers
  • extra oiling orifices like are sometimes used at the front of the Chevy block to oil the cam gear-to-block interface
  • drilled oil plugs like used on Pontiac engines to oil the cam/distributor gear
  • mods to the Chevy distributor housing that bleeds oil from the lifter galleys crossover to oil the cam/distributor gears, etc.
  • any other trickery that causes an abnormal 'loss' of oil that wouldn't happen under normal circumstances
The idea that the oil pump will pump the pan dry has very little credibility to begin with, so shouldn't be a consideration for choosing an oil pump in the first place. The MAIN issue w/the pump and oil pan is to correctly space the oil pick up from the bottom of the oil pan. Many cases of the oil pump "pumping the pan dry" was actually a case of the bottom of the pan getting sucked up against the too-close pick up, or from cavitation, not from too much volume.
 

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WOW!!!!!! Can you two tell me if its more better to pore in one oz. or one an one half ounces of 2 stroke oil into a gal. of gas.For my weed wacker.Just calm down.
 

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So cubic inch displacement per revolution is "essentially useless”, the engineers at fluid power are idiots for suggesting that a hydraulic pump can be sized in this way.
Well i'm glad you brought this to mine and anybody reading this attention.
I should stop my investigation into the Chevy oil pump as i will surly be over whelmed by the complexity of the situation.
Thank you for your input on this thread

You apparently didn't talk to an engineer, likely just a secretary. And there's no reason to stop as long as you're willing to put forth more effort than playing with a calculator- that is NOT an "investigation". Half baked ideas just need more cooking time.
 

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WOW!!!!!! Can you two tell me if its more better to pore in one oz. or one an one half ounces of 2 stroke oil into a gal. of gas.For my weed wacker.Just calm down.
It depends on the engine, but its better to be a little on the shy side than little on the heavy side- which is contradictory to what many people believe.
 

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More machine than man
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It depends on the engine, but its better to be a little on the shy side than little on the heavy side- which is contradictory to what many people believe.
True. Since a carb meters by volume, when you add more oil it causes a lean condition. But it is kind of a moot point if you run a synthetic 2 stroke oil at a 100:1 ratio.
 

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If you want the best wet sump pump there is, get a Titan gerotor pump. For continuous use above 7000RPM, there is no better pump.
For more conventional SBC wet sumps, I use the BBC pump that is modified to put the bypas oil back in the pan rather than churning it in the gear housing.
 

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WFO
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True. Since a carb meters by volume, when you add more oil it causes a lean condition. But it is kind of a moot point if you run a synthetic 2 stroke oil at a 100:1 ratio.
People learn this either by listening to those who know, or by sticking a piston at speed. Not fun when you're laid w-a-y over in a long righthand sweeper just tipping WFO into 6th gear...:pain::evil:

My lesson came cheaply- just two and a half gallons of high test and some castor oil was all it cost me. Plus I was racing karts, not bikes.:mwink: I could have remixed the fuel by adding more gas, but I didn't want to chance getting it wrong so I burned it in the 'yard wrecker. For a little while running it smelled just like the pits during a race!

BelRay and Klotz (among others) were selling synthetic 2-stroke oil even back then, but castor was what I learned on so I stuck (no pun intended) w/it throughout my kart 'career'.
 

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Vd=0.7854B2S, CR=Vd+Vc/Vc
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Discussion Starter · #20 ·
You apparently didn't talk to an engineer, likely just a secretary. And there's no reason to stop as long as you're willing to put forth more effort than playing with a calculator- that is NOT an "investigation". Half baked ideas just need more cooking time.
Ridiculing me for using a calculator while doing some basic analysis on the Chevy gear pump is not what Hot Rodding is about.
If you can't accept that the Chevy gear pump can be for comparison purposes defined with a math formula found in a hydraulics handbook than that is your right.

The formula i used is available online and in the Womack Educational Publications fluid power data book used by hydraulic engineers the world over, it's on page 25 titled "replacement of pump or motor"

Please feel free to present a more satisfactory formula that shows pump output so we can make a definitive comparison.
 
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