Moparts

High Volume vs Standard Volume Oil Pump

Posted By: GTX MATT

High Volume vs Standard Volume Oil Pump - 11/19/12 03:46 PM

Alright guys, so I initially bought a high volume pump because I was planning to run an 8 quart pan. I decided I didn't want to deal with ground clearance issues, and bought a repop 71 Hemi 6 quart pan. I bought a standard volume pump at the same time, figuring I don't want to risk running the pan dry and I'd use the HV pump on something else. Now I'm starting to rethink. What thinks Moparts?

This is a street car with .0027 clearance on the mains and .0025 on the rods. It will see some strip time and is driven hard on the street.
Posted By: B G Racing

Re: High Volume vs Standard Volume Oil Pump - 11/19/12 04:30 PM

I would stay with the hi-volume pump,if you have an issue with low sump volume just add an extra quart.
Posted By: jamesc

Re: High Volume vs Standard Volume Oil Pump - 11/19/12 05:50 PM

personally i think the HV pump sucking the pan dry is a wives tale. if both the HV and standard pump carry the same oil pressure throughout the operating range then the exact same amount of oil is being pumped through the engine the only difference is the HV pump is internally recirculating more oil.

the best pump for the application is the smallest pump that will deliver the desired oil pressure under the expected operating conditions. anything else is a waste of HP and unnecessary load on the drive system
Posted By: GTX MATT

Re: High Volume vs Standard Volume Oil Pump - 11/19/12 05:55 PM

Also want to throw in this engine has aluminum heads
Posted By: Cab_Burge

Re: High Volume vs Standard Volume Oil Pump - 11/19/12 07:03 PM

Quote:

personally i think the HV pump sucking the pan dry is a wives tale. if both the HV and standard pump carry the same oil pressure throughout the operating range then the exact same amount of oil is being pumped through the engine the only difference is the HV pump is internally recirculating more oil.

the best pump for the application is the smallest pump that will deliver the desired oil pressure under the expected operating conditions. anything else is a waste of HP and unnecessary load on the drive system

OP, my 518 pump gas stroker has more bearing clearances than yours as well as oiling the rockers full time, I use the same oil pan I use 5W20WT Valvoline non synthetic, I have to keep the oil level above the add mark at the drag strip, if I don't the oil pressure will drop off when I let off. I cross the finish line between 6500 and 7000 RPM depending on which rear tires are on the car, it runs 134.+ MPH I did cut the bypass spring down so I have right at 65 lbs of pressure at 6500 RPM with hot oil on the engine dyno, I think it was 1 1/2 coils
Posted By: dartman366

Re: High Volume vs Standard Volume Oil Pump - 11/19/12 07:25 PM

Quote:

personally i think the HV pump sucking the pan dry is a wives tale. if both the HV and standard pump carry the same oil pressure throughout the operating range then the exact same amount of oil is being pumped through the engine the only difference is the HV pump is internally recirculating more oil.

the best pump for the application is the smallest pump that will deliver the desired oil pressure under the expected operating conditions. anything else is a waste of HP and unnecessary load on the drive system

Cannot agree more, altho I have not taken time to mess with mine and just run a HV pump.
Posted By: Streetwize

Re: High Volume vs Standard Volume Oil Pump - 11/19/12 07:57 PM

I run a blueprinted and hand ported stock volume pump on any of my big blocks that turn up to ~7200 rpm. You'd be suprised what they'll keep up with by just opening up the inlet to 1/2" and chamfering that severe 90 degree turn in the pump head itself

Both the high-volume and standard pumps seem to have the same inlet/outlet "head" casting; I for one never saw the point/value of opening up the block pick-up to 1/2" and leaving the restrictive 3/8" id head on the pump

if you make it easy to supply the oil to the pump and provide it relatively unrestricted to the mains, you make it a lot easier for the system to do its job.

The interesting thing about oiling systems is since you have a series of controlled orifice "bleeds" ; so as you bleed pass each journal you have proportionally less oil pressure available for the next one in the path. Therefore the 'easiest' (and arguably most effective) ways to help the system "circuit" is to reduce as many upstream bottlenecks as you can. The pump head is the first place I go toward improving the system.
Posted By: Mopar Guy

Re: High Volume vs Standard Volume Oil Pump - 11/19/12 09:49 PM

There is one more benefit whit a stock oil pump and that is that you save the drive gear if you use a roller cam as there has to be a bronze gear and the std pump will give you the oil you need so it´s a win win deal and more hp to the rear tires !!!
Posted By: HYPER8oSoNic

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 01:16 AM

Quote:

I run a blueprinted and hand ported stock volume pump on any of my big blocks that turn up to ~7200 rpm. You'd be suprised what they'll keep up with by just opening up the inlet to 1/2" and chamfering that severe 90 degree turn in the pump head itself

Both the high-volume and standard pumps seem to have the same inlet/outlet "head" casting; I for one never saw the point/value of opening up the block pick-up to 1/2" and leaving the restrictive 3/8" id head on the pump

if you make it easy to supply the oil to the pump and provide it relatively unrestricted to the mains, you make it a lot easier for the system to do its job.

The interesting thing about oiling systems is since you have a series of controlled orifice "bleeds" ; so as you bleed pass each journal you have proportionally less oil pressure available for the next one in the path. Therefore the 'easiest' (and arguably most effective) ways to help the system "circuit" is to reduce as many upstream bottlenecks as you can. The pump head is the first place I go toward improving the system.





with 'Wise. I would definitely enlarge the suction side (pump head) of the block to 1/2" (Hemi diameter) and chamfer the 90 degree bend to the pump mount. As far as the pump is concerned with, hi-volume is what I'd go with. 6 Quart pan is fine, but and 7-8 quart "kickout-style" pan is a little better. More capacity, ground clearance is good but... it may or may not work for you, depending on your steering linkage clearances and chassis. Check on it. Oil lubricates and HELPS cool also, the more oil capacity, the better.

Posted By: ahy

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 03:39 AM

Agree run the smallest pump that will meet your needs. The main benefit of the HV pump is improved hot oil pressure at idle and low RPM. With your clearances, you may need/want the added pressure, especially if the main bearings are full groove. Personally I would (and did) pick the HV pump and Hemi pan combo.
Posted By: GTX MATT

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 06:50 AM

Quote:

Agree run the smallest pump that will meet your needs. The main benefit of the HV pump is improved hot oil pressure at idle and low RPM. With your clearances, you may need/want the added pressure, especially if the main bearings are full groove. Personally I would (and did) pick the HV pump and Hemi pan combo.



Thats pretty much what I'm asking, with the motor on the loose side at .0027 and .0025 what kind of oil pressure is the standard volume pump going to make? I'd like to have at least 30-35 lbs at hot idle, 55-65 at cruise/high rpm.
Posted By: BSB67

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 12:48 PM

There are so many other clearances that matter that we don't talk about so it is hard to say.

I have .0028/.0022, full groove mains, full time unrestricted oiling to the valve gear, hand massaged std. rotor pump, and 5-30 full synthetic oil. Hot, in gear (700 rpm) is about 18-20 psi, neutral (850 rpm) 20-23 psi. It climbs to 50+ with the slightest amount of throttle.
Posted By: Dragula

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 02:27 PM

Quote:

personally i think the HV pump sucking the pan dry is a wives tale.



I will send you my burnt rod.....Was running 9.5 quarts, and starved one rod.
Posted By: sr4440

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 02:37 PM

Quote:

Quote:

personally i think the HV pump sucking the pan dry is a wives tale.



I will send you my burnt rod.....Was running 9.5 quarts, and starved one rod.



was it number 6 by any chance?

Joe
Posted By: Dragula

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 02:42 PM

It was #3 or #4...
Posted By: rickstershemi

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 02:52 PM

my 408" stock 360 block, HV Melling Pump, 90* Adaptor w/Wix 5151R filter, runs 60lbs at idle once everything is up to temp with 10w30 VR1, but will jump past 90* at a moderate rise in rpm on the test stand...?????

Seems to be getting plenty of oil up top...????

Rickster
Posted By: jamesc

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 03:32 PM

Quote:

Quote:

personally i think the HV pump sucking the pan dry is a wives tale.



I will send you my burnt rod.....Was running 9.5 quarts, and starved one rod.



everyone is entitled to their opinion mine is that if you have 2 1/2 gallons of oil in an engine and can't keep things wet there's something else wrong other than the size of the pump, the oil pumps job is pretty simple. if you have that much oil in suspension then the return is inadequate, clearances too loose or some other oil control problem is going on (or a combination).

if you burned something up the HV pump was NOT the cause

what people just don't seem to grasp is that no matter WHAT size pump is on an engine if at any given point in the operating conditions the oil pressure is the same then the flow of oil through the engine is the same...period

if you're at 7000 rpm and have 75# of pressure with a stock pump and 75# with a HV pump then the flow THROUGH the engine is the same.

IF you have 75# with a stock pump and 60# with a HV pump (due to relief spring differences) then the STOCK pump is circulating more oil through the engine.

don't believe me ask a hydraulics engineer
Posted By: Streetwize

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 03:52 PM

JamesC,

Well yes and no, Gauge pressure doesn't always tell the entire story since there are both series and parallel hydraulic circuits in the motor and the gauge pressure reading locations in the circuit can vary somewhat by the motor. It depends to some degree where the failure is. For example if a #5 rod bearing fails it severely reduces the oil to the rods downstream on the crank from it, but the rods upstream and closer to the pump (though much lower) could still have adequate pressure. Depending on where the sender is on that motor you may see different gauge readings. for example a small block sender is pretty close to the pump as it's off the #5 main while on a big block the sender is off the back of the block (clear on the other side of the crank) while the pump is up front. so Low pressure at idle to me is a bit relative, In line with what Rickster finds on his motor, small blocks always seem to have way better GAUGE idle pressure than big blocks from my experience, I think the location of the sender relative to the pump discharge has a bit to do with it but I may be wrong.

As I said earlier one of the best ways to insure circuit flow is to tackle the pump discharge efficiency since it potentially has a positive effect on everything in the system.

I agree a 9.5 quart system sucking dry and leading to a rod failure seems unusual, a motor autospy can usually determine the cause and effect.
Posted By: B G Racing

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 05:00 PM

With our limited experience,the standard non hi-volume pump will not keep up with the demands of a hemi above 6500rpm.We have seen increased bearing wear as well as topend wear.If the pump starves any area and oil passages, cavitation can occurr,air lubes nothing.As we have mentioned time and time again a hemi on a adverage 10 second pass will circulate 10 qurts of oil aprox. 3xs.This is why the need for larger sumps and more elaborate oil systems are critical.Volume is as important or more so as pressure.We have seen the big SS race hemis with hardly any oil pressure at idle and aprox.65# down track survive because of the volume of oil in the sump,accumulaters and a big pump to deliver that volume.That a hemi retains more oil in the top makes a dual line system and large sump critical over 7000rpm. My opinion only.



If the results don't support the theory,find another theory.
Posted By: Thumperdart

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 05:11 PM

Quote:

Quote:

personally i think the HV pump sucking the pan dry is a wives tale.



I will send you my burnt rod.....Was running 9.5 quarts, and starved one rod.

You my friend MAY have other problems..........I run 5w30 Mobile-1 and w/6-quarts in an 8-quart pan and a hv pump I never hurt anything and my bearings looked real good after 7 years of street/strip thrashing...........
Posted By: Streetwize

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 05:16 PM

Bob,

That's a GREAT point with the Hemis and it really amazes me how much oil (quantity) meters through a motor during a full throttle pass.

The hemi head has (I'm guessing) probably more than twice the oil coated surface area for oil to collect up top and drainback to the sump is far more of an issue, so it's logical that the more oil that is (for want of a better word) "dwelling" on an engine surface and not draining immediately to the pan has to be made up for in the system volume.

It hasn't been mentioned here but Oil flow is also a critical cooling component as it wicks away heat from all of the engine surfaces, and on a drag car the valve springs particularly.

FWIW, Bob's tip of run the HV and an extra quart was the way we used to do it 30+ years ago and I never lost a bottom end to oil related failures, even at 8200 rpm in a W2 340 which was wound pretty tight for a street motor in the late 70's-early 80's. And the front sump design of the Typical A,B, E bodies didn't help things either!
Posted By: B G Racing

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 05:31 PM

Quote:

Bob,

That's a GREAT point with the Hemis and it really amazes me how much oil (quantity) meters through a motor during a full throttle pass.

The hemi head has (I'm guessing) probably more than twice the oil coated surface area for oil to collect up top and drainback to the sump is far more of an issue, so it's logical that the more oil that is (for want of a better word) "dwelling" on an engine surface and not draining immediately to the pan has to be made up for in the system volume.

It hasn't been mentioned here but Oil flow is also a critical cooling component as it wicks away heat from all of the engine surfaces, and on a drag car the valve springs particularly.

FWIW, Bob's tip of run the HV and an extra quart was the way we used to do it 30+ years ago and I never lost a bottom end to oil related failures, even at 8200 rpm in a W2 340 which was wound pretty tight for a street motor in the late 70's-early 80's. And the front sump design of the Typical A,B, E bodies didn't help things either!



Circulation helps with the cooling also.With a hemi the large area of trapped or retained oil at the top is a critical issue,also the poor drainback design(holes at each corner of the heads)is a concern.On many of our large high hp engines we add two drain back lines per side to help return the oil to the sump.
Posted By: jamesc

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 05:46 PM

Bobby in a liquid fluid system a change at any location will be reflected by a change at any other point in the system. though technically liquids are compressible in practice they are considered as incompressible.

if you fail a rod bearing the downstream components will not see less oil unless the overall system pressure drops. as long as the system pressure remains the same then the same amount of oil is being delivered to the undamaged components regardless of their location however the flow through the damaged bearing will increase.

now IF the pump is not capable of maintaining the pressure that existed prior to the failure then the other components may be compromised.

you are correct with regards to gauge port location on SB vs BB. i would expect a SB to show higher gauge pressure because it is right above the pump so to speak. however when we refer to "oil pressure" we don't move the gauge port around we are always reading it from the same location so in this respect it does reflect what is happening in the system.

i fully agree with your ideas about reworking the stock pump and system. in many cases it may be all that's required and is imho the better route if it is sufficient

fluids (like electricity) flow from a point of high potential to a point of low potential.

oil serves three functions, to lubricate, cool and cleanse and engine in that order.



Bob i fully agree that due to the valve gear the hemi would require more oil and would not be surprised that a stock pump is not adequate for high speed operation and improved oiling is necessary

having said that there's absolutely no way you're circulating 30qts of oil through an engine in 10 seconds. the milodon HV pump is rated at approx 20 GPM or 1.33qts per second. the absolute maximum a milodon HV pump could move in 10 seconds is 13.3qts and i highly doubt that is happening

i really wish i was better at explaining this stuff

so often we hear "the HV pump will suck your pan dry" (often referring to the stock style HV pumps)...only if there's some other problem(s) that need to be addressed. oil returns compromised, no windage control, engine clearances too loose. overall the oil NOT being in the pan (where it's supposed to be) for the pump to pick up

if HV pumps were such a detriment to an engine then the really HV pumps such as the milodon, titan etc would be engine destroyers not a component that helps an engine live.


everyone is entitled to their opinion(s) these are mine
Posted By: 10.90 Racer

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 07:21 PM

Quote:

Quote:

Quote:

personally i think the HV pump sucking the pan dry is a wives tale.



I will send you my burnt rod.....Was running 9.5 quarts, and starved one rod.

You my friend MAY have other problems..........I run 5w30 Mobile-1 and w/6-quarts in an 8-quart pan and a hv pump I never hurt anything and my bearings looked real good after 7 years of street/strip thrashing...........



^
Posted By: Mopar Guy

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 08:48 PM

I built a 505 stroker and used a roller hydralic cam so my choise whas a stock std volume oilpump and it whas set at 55 psi by Melling.
The resone for my choise whas the fact that i had to use a bronze drive gear for the pump so i whanted to save on the wear of that gear and i have about 30 psi on idel and 50 psi if i rev the engine just a littel =) If i push the engine hard then i lose about 5 psi on idel but thats it and by my book that´s ok so why put a hi volume pump if its not needed !?
Posted By: bwdst6

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 09:15 PM

Quote:

The hemi head has (I'm guessing) probably more than twice the oil coated surface area for oil to collect up top and drainback to the sump is far more of an issue, so it's logical that the more oil that is (for want of a better word) "dwelling" on an engine surface and not draining immediately to the pan has to be made up for in the system volume.

A competitive AH car will have 3 qt’s of oil in the pan and 2-3 in the sump. Running over 9000rpms driving a very low back work pump with no bypass fed by a single external line.
Posted By: B G Racing

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 09:34 PM

It's not any theory of mine,but something that Chrysler engineers had proclaimed and informed racers of years ago that on a adverage 10 second pass at aprox. 8000rpm and to retain enough volume in the sump 10 quarts would need to circulate 3Xs.I've never had any reason to confirm or refute this claim,but had an incident where Mark Davis and I was testing a Milodon dual line system with a drill and 2 five gallon buckets with 8 quarts of oil.While priming the pump up to about 1800rpm,Mark found himself covered in most the 8 quarts before he could face the pump outlet to the second bucket and I could release the drill trigger alot less than 10 seconds.Also keep in mind that at any given rpm that more than 1/2 the sump volume is in the engine not the pan.Also consider the amont of oil in a drysump system that does circulate on even quicker passes.
We need also to consider some adverage bracket engine that have 10quart sumps and 3quart accumulators(13qts)and at the end of the pass when the pressure drops on hard decel and accumulator has to back up the system,where is all that oil.
I'am not going to say my refrence of the claim and findings of Chrysler engineers of 1970s is the final fact,but I'll buy it till someone can prove otherwise.Maybe it's a sales gimmick to get us to buy big pumps,pans and tons of oil.Maybe someone will try the Mark and Bob experiment with a stopwatch and report back to us.
Posted By: 10.90 Racer

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 10:18 PM

Quote:

It's not any theory of mine,but something that Chrysler engineers had proclaimed and informed racers of years ago that on a adverage 10 second pass at aprox. 8000rpm and to retain enough volume in the sump 10 quarts would need to circulate 3Xs.I've never had any reason to confirm or refute this claim,but had an incident where Mark Davis and I was testing a Milodon dual line system with a drill and 2 five gallon buckets with 8 quarts of oil.While priming the pump up to about 1800rpm,Mark found himself covered in most the 8 quarts before he could face the pump outlet to the second bucket and I could release the drill trigger alot less than 10 seconds.Also keep in mind that at any given rpm that more than 1/2 the sump volume is in the engine not the pan.Also consider the amont of oil in a drysump system that does circulate on even quicker passes.
We need also to consider some adverage bracket engine that have 10quart sumps and 3quart accumulators(13qts)and at the end of the pass when the pressure drops on hard decel and accumulator has to back up the system,where is all that oil.
I'am not going to say my refrence of the claim and findings of Chrysler engineers of 1970s is the final fact,but I'll buy it till someone can prove otherwise.Maybe it's a sales gimmick to get us to buy big pumps,pans and tons of oil.Maybe someone will try the Mark and Bob experiment with a stopwatch and report back to us.



You have to remember, most of the oil is just pumping against resistance . The amount of oil actually flowing is what all the bleed off clearances in the engine will allow...........
Posted By: jamesc

Re: High Volume vs Standard Volume Oil Pump - 11/20/12 11:04 PM

Quote:

You have to remember, most of the oil is just pumping against resistance . The amount of oil actually flowing is what all the bleed off clearances in the engine will allow...........




exactly, and people need to get hold of this fact

the milidon pump (according to them and i think they're actually BB ford rotors) is rated at 19-21 GPM of course this is speed dependent but one would have to think that they rated it at a decent speed

these things determine how much oil is actually FLOWING THROUGH the engine

> oil pressure

> clearances (leaks)

> oil viscosity (temperature impacted)

because oil pumps are positive displacement they MUST have a relief system which is the function of the relief spring and valve. any oil that the pump is moving that is not required to maintain the pressure that the relief valve is set at spills from the discharge directly back into the suction. it is simply pumped in circles, the amount of oil pumped by a PD pump is directly proportional to its speed.

oil pumps, hydraulic pumps, roots and screw type blowers are all examples of a positive displacement pump, for each rotation they move an exact amount of fluid.

i have seen PD hydraulic pump bodies literately split in half when they were not protected by a relief valve and someone started the engine with the pump discharge closed.

water pumps, turbochargers, pro chargers are all examples of centrifugal pumps, these type pumps allow for "slip" meaning you can block the discharge and the pump won't lock it will slip.

because of their design centrifugal pumps/compressors are subject to a phenomenon know as surge and i'm not even going to try to explain that and NPSH here
Posted By: 440Jim

Re: High Volume vs Standard Volume Oil Pump - 11/21/12 03:17 AM

Quote:

I use the same oil pan I use 5W20WT Valvoline non synthetic, I have to keep the oil level above the add mark at the drag strip, if I don't the oil pressure will drop off when I let off.

That pan is known to have issues during deceleration (braking). But if you keep the oil level high enough, it will be fine.

As far as the std vs high volume oil pump, IMO it has more effect at idle than anywhere else. If the std gives you at least 15 psi at hot idle, I would run it. Otherwise go with the high volume. This can be very sensitive to idle speed (700 rpm or 900 rpm), so running a couple hundred more rpm can solve some low pressure issues at hot idle.

FWIW,
In my 511 CID wedge big block, I have run both a HV pump and a std volume pump with the internals smoothed. Using the same bypass spring in both pumps, the oil pressure going down the track was identical. The only difference was the idle oil pressure, most notably only when the oil was hot (which is hard to do in a drag race car). After one season with the std volume pump, the inside looked great (bearings, crank, pistons, etc.). But I didn't see any ET improvement. I think drain back and the amount going to the heads (mine has Indy heads with restrictors) along with oil pan is more important than the pump volume.
Posted By: B G Racing

Re: High Volume vs Standard Volume Oil Pump - 11/21/12 05:27 PM

Race engines with bigger clearences need more volume. Oil systems is not a place to gamble or skimp on.
Posted By: Cab_Burge

Re: High Volume vs Standard Volume Oil Pump - 11/21/12 08:15 PM

Quote:

Race engines with bigger clearences need more volume. Oil systems is not a place to gamble or skimp on.

Brother, that be the TRUTH
Posted By: M_D

Re: High Volume vs Standard Volume Oil Pump - 11/21/12 11:51 PM

Quote:

Race engines with bigger clearences need more volume. Oil systems is not a place to gamble or skimp on.



I agree, enlarging clearances will require more volume of flow to maintain the same pressure, all other things being more or less equal. But, that doesn't automatically mean a standard pump won't work, it may or may not, depending on the exact factors involved which primarily amount to pump capacity and the flow needed to have sufficient pressure with given clearances. If the pressure is adequate, which indicates the flow is also adequate for that combination, then installing a larger pump will just bypass more oil assuming the pressures are equal.

Let's compare this to flow bench principles. The flow bench is adjusted to maintain the same pressure as the test is repeated at various valve lifts. When a port flows more air, you increase the volume of air being pulled (or pushed) through it until the pressure equals the standard you are using. Having a means to regulate pressure (a bypass or return) allows pumps to work over a certain range of flows. So, as long as a flow bench is capable of pumping enough air to reach the desired test pressure a large bench (pump) will not gain anything as you just bypass or regulate the flow downward to keep the pressure in check.

My 2 cents on the oil pumps is a bigger (within reason) pump is better than one too small, but it isn’t better than one that is smaller but big enough.
Posted By: B G Racing

Re: High Volume vs Standard Volume Oil Pump - 11/21/12 11:57 PM

Quote:

Quote:

Race engines with bigger clearences need more volume. Oil systems is not a place to gamble or skimp on.



I agree, enlarging clearances will require more volume of flow to maintain the same pressure, all other things being more or less equal. But, that doesn't automatically mean a standard pump won't work, it may or may not, depending on the exact factors involved which primarily amount to pump capacity and the flow needed to have sufficient pressure with given clearances. If the pressure is adequate, which indicates the flow is also adequate for that combination, then installing a larger pump will just bypass more oil assuming the pressures are equal.

Let's compare this to flow bench principles. The flow bench is adjusted to maintain the same pressure as the test is repeated at various valve lifts. When a port flows more air, you increase the volume of air being pulled (or pushed) through it until the pressure equals the standard you are using. Having a means to regulate pressure (a bypass or return) allows pumps to work over a certain range of flows. So, as long as a flow bench is capable of pumping enough air to reach the desired test pressure a large bench (pump) will not gain anything as you just bypass or regulate the flow downward to keep the pressure in check.

My 2 cents on the oil pumps is a bigger (within reason) pump is better than one too small, but it isn’t better than one that is smaller but big enough.



All things being equal,"bigger is always better"If two good look guys went out on the town and one came up shorter than the other,which one has a better chance of getting lucky?
Posted By: M_D

Re: High Volume vs Standard Volume Oil Pump - 11/22/12 12:19 AM

lol, I guess it depends on which parts are bigger! Then again, do you look for dates that probably have big clearances?
Posted By: quickd100

Re: High Volume vs Standard Volume Oil Pump - 11/22/12 12:58 AM

When you're running a very expensive motor and leaning on it hard I'd rather be safe than sorry. Oil is your friend, to little of it gets REAL expensive fast.Dave
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