oil pump question ?

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made 10 passes down the drag strip (3 this weekend) with stock 5 qt pan with high volume pump...never sucked the pan dry....

old BS
 
I don't .,but i think there may be one in this rebuilt engine that I bought. It came out of a truck, and it had a 7qt oil pan on it..It wouldn't fit in my car, so I put a 5qt.pan on it and I was just wanting to know.
 
All I will say as for years I've been building engines with stock pans and HV oil pumps. It never crossed my mind that a HV pump might suck the pan dry. Never had an issue, maybe lucky? Maybe not.
 
where would the oil go ?

a high volume pump only pumps more oil around the engine, sending it down into the pan quicker then a regular volume pump

unless you have a high volume block that would be able to store more oil before it streams down into the pan I don't see how it would suck it dry

if anything, a high volume pump will refill the pan quicker then a regular one, those are the ones you should worry about



(go ahead, read it again, it makes sense)
 
diymirage said:
where would the oil go ?

a high volume pump only pumps more oil around the engine, sending it down into the pan quicker then a regular volume pump

unless you have a high volume block that would be able to store more oil before it streams down into the pan I don't see how it would suck it dry

if anything, a high volume pump will refill the pan quicker then a regular one, those are the ones you should worry about



(go ahead, read it again, it makes sense)
Click to expand...

It sure does make sense. That's the simplest explanation of it I have ever seen. Good job, Buckwheat.
 
Well I put an Hv on my 360 for a different reason. I opened up the oil suppy holes to the rocker arms, to supply extra cooing oil to the springs, cause I wanted to run extra pressure there so I could rev the snot out of her, on a little cam. I had alum roller-tipped rockers on non-banana groove shafts, So figured a little extra oil wouldnt hurt.I also opened up the clearance between all the little spacers up there to let the arms move sideways a bit.
What I found out was that my stock Eddies like to accumulate oil up there. And when I entered my first grass auto-cross(grass is so much fun), it seemed like a lot of oil stayed up there, as it filled up the breathers and burned on the headers. Did it pump the pan dry? No, I had a 7qt roadrace pan on it.
So the next winter when I always(at that time) take the motor apart for inspection, I modded it,again. I cut those Eddies. I cut some nice wide shallow drainback channels at the firewall ends(the low ends). Then, knowing that our Mopes like to store oil in those little cupped areas between the lifters, I drilled some holes there too. Yeah I know now it dribbles oil down onto the crank and cam, which supposedly costs power.Hey, its a street motor.It already has more power than the suspension can handle. Well I made those holes just big enough to sloooowly pass hot oil.The idea being that those cups would not store oil there after shut down. Some of us remember the leaded gas era, and how those cups were always full of lead/sludge.
As a sidenote,I did all the other usual oiling mods , at the time of first-build, including port-matching the oilpump to the block,drilling out certain oil passages, extra oil clearances here and there, etc.
So back to the question; With the 7qts in the bottom, no. But how would I know? During the time-trial whos got time to watch the oil gauge? So when I get back to the pits, the best I can do is listen to my lifters, and trust the mods.So far so good.
On the street, I run 5qts. Two gear blasts dont count for much. So far so good. Im at 11 years from that mod, and guessing 80,000 miles or more,from that winter; 125,000 from day-one.
Oh yeah, almost forgot, the drainback channels I cut, seem to be working; no more burning oil on the headers.
Also forgot to mention, I have no oil gauge in the car, other than that oem slowpoke.
The way I figure it, an oil gauge is just there to make me worry. Without it I can enjoy the blasts.I like to keep my eyes on where Im going.If I had a gauge, Id be checking it after every blast. What good is that?If damage occurs during the blast, its all over anyway.So if you check it , after,and alls good, you get a warm feeling inside.I get the same feeling when the lifters are quiet, and the rods aint banging.Its a street engine.It doesnt work that hard.So far so good.
I say, fogetabowdit.
 
diymirage said:
where would the oil go ?

a high volume pump only pumps more oil around the engine, sending it down into the pan quicker then a regular volume pump
Click to expand...
Errr... No.. A high volume pump will recirculate oil within the pump itself via the relief valve and only supply more oil around the engine if the engine can dispose of it via extra clearances or oiling mods of some type. Such a simple system, but so totally mis-understood..
#-o
 
Bakerlite said:
Errr... No.. A high volume pump will recirculate oil within the pump itself via the relief valve and only supply more oil around the engine if the engine can dispose of it via extra clearances or oiling mods of some type. Such a simple system, but so totally mis-understood..
#-o
Click to expand...

wouldn't that be a moot point ?
if the relief valve opens and the pump pumps oil to itself it will never run dry
(in this case i'm conveniently counting the pump as part of the oilpan, the reservoir)

my point was, the only time there is an issue is when you have a block that could accommodate more oil, either by larger oil passages, a remote cooler or what not
 
I've run high pressure, high volume oil pumps in 5 quart pans for 40 years and never sucked the pan dry. Same engine, same pump, power shifted between 6,000 to 7,000 RPM. No Problem. Maybe if you had lower gears and could slam a good holeshot, you could lose oil pressure but that would be pushing oil back in the pan and uncovering the pickup.
 
I've also run HV pumps, HP springs, with 5 quart pans with no problems for years...
 
it is called an m72hv for a reason, it is bigger than a stock pump, it pumps more volume. the relief valve is controlled by a spring - more related to pressure. for 11 seconds or so a hi volume pump and a stock pan (usually no baffles so if the acceleration is good the oil sloshes to the rear and the pickup sees less oil) can get by. but for a longer blast what can happen with stock heads and block oil drainback areas is the oil does not drainback fast enough and the pan gets sucked dry, oil pressure temporarily is zero. I have seen it
 
I think some of you are missing the point. A HV pump will pump the same amount of oil as a stock pump when used in a stock engine, otherwise it just goes round and round the relief valve.
 
"A HV pump will pump the same amount of oil as a stock pump when used in a stock engine, otherwise it just goes round and round the relief valve"
I hesitate to call BS, but I just cant agree with that statement. I have thought, and thought, and thought, about it. Its just not coming to me.So for now Im just going to think on it some more.
 
Unless you change the size of the oil galleries...the HV pump will pump the same amount of oil as a standard...is correct..
 
Higher volume pumps are not necessary with a stock pan in an engine that won't see hi RPM very often. Seen as many running Hi-volume pumps just fine on the street too. Overkill, maybe, but probably better to err on the side of caution than to need it & not have it. I've built a few & seen many more street engines that are just fine running a stock pump.
High volume pumps are an advantage when you have looser tolerances in the motor(as a race prepped engine would) so the added volume in the pump can maintain the desired pressure. It will only produce as much pressure as the relief spring will allow thus regulating the amount of oil pumped. The added pump volume also helps to prevent cavitation in the pump at higher RPM.
So the real question is can you get by with a stock pump? If you already have a good Hi-volume pump in it I'd leave it in there.
 
OK lets back up the bus.
Bakerlite
Are you saying that at, lets say, 3000rpm, when the stocker has not yet reached its full pumping capacity, thus not yet bypassing fluid, that the HV pump with its bigger rotors at the same 3000rpm, would be pumping the exact same quantity of oil?
 
theory...after theory...after theory......here is an actual

made 10 passes down the drag strip (3 this weekend) with stock 5 qt pan with high volume pump...never sucked the pan dry....

shifting at 6000 rpm....did not suck the pan dry.......LOL

please post some actual fact of a pan being SUCKED DRY....
 
AJ/FormS said:
OK lets back up the bus.
Bakerlite
Are you saying that at, lets say, 3000rpm, when the stocker has not yet reached its full pumping capacity, thus not yet bypassing fluid, that the HV pump with its bigger rotors at the same 3000rpm, would be pumping the exact same quantity of oil?
Click to expand...

At lower RPM the smaller pump will deliver less output, in this case less than engine can accommodate. Once the pump delivers more than the engine can use it will start bypassing, and the output will be no more than the engine needs regardless of RPM. Since the stock pump will bypass (hopefully before 3000 RPM) even it is too large at high RPM. Also, since either pump can deliver more than the engine can use, engine oil demand, not pump volume will be what determines how fast the pan gets emptied. The HV pump is no more likely to empty the pan.
 
AJ/FormS said:
OK lets back up the bus.
Bakerlite
Are you saying that at, lets say, 3000rpm, when the stocker has not yet reached its full pumping capacity, thus not yet bypassing fluid, that the HV pump with its bigger rotors at the same 3000rpm, would be pumping the exact same quantity of oil?
Click to expand...

Ok, you need to look at it this way. Say you take a tube( oil gallery) and put a restrictor at the end of it that replicates all of the places in your engine that oil leaks past back to the sump.
Ok , now, say that we need to pump 40 gallons per minute to reach a pressure of 60 Psi in the tube and open a recirculating relief valve. You run your stock pump , and at 3500 RPM it reaches the 40 Gpm /60 Psi limit and opens the valve and recirculates the oil. Then you run the HV pump and because it tries to pump a larger volume of oil it reaches 40 Gpm earlier and opens the relief valve at 3000 rpm.
As you can see, all the HV pump does is start bypassing earlier, at lower RPM.
The restrictor is still passing the same amount of oil at 60 psi for both pumps.
Volume and pressure are related, only when you try to push more volume than the restrictor can handle will you see an increase in pressure.
If you open up the restrictor and pass more oil than the stock pump can supply, then that's the time you need to go to a higher volume.
There is a reason why oil pressure gauges are best mounted at the highest gallery point in the engine and not on the pump..
 
I guess I found a flaw in my logic
it is not the pump that is the limiting factor in this equation, it is the capacity for oil return

I gues it is kinda like replacing a 3 lane south bound highway with a 4 lane highway
you can get more traffic out of there, but if there is only one northbound lane, then there would be a replenishing issue

mhhh
 
No, it won't "suck the pan dry" because it's just dumping most of it out the bypass anyway. All it's doing is trying to compress a fluid - which just means it's wasting power and making a little heat.
Unless the engine has race clearances and plans to race it, or it's whipped, there is no need for a HV pump. In any of those instances, you should also have a bigger sump because there may be an issue with it not draining back fast enough at a higher rpm.
 
Well, I understand your thinking ,but not agreeing just yet.
Back to my example;3000rpm
Say the stock pump is putting out 30 psi into said restrictor.
Ima thinking The HV pump in pushing more oil might develop some higher pressure,perhaps 35psi into the same restrictor. However, with the higher pressure,its putting more oil through that restrictor.
We havent got into bypass mode yet.

I think of it as a garden hose. Set the volume delivery at less than max capacity, at the valve. Jam a straw into the delivery end, to represent the restrictor. Measure the output per unit of time.
Then repeat the test , with more volume delivery from the valve.The pressure before the valve is the same in each case; whatever the system is set to. If you like, you could plumb a pressure gauge just before the straw. Then you could compare the pressure difference. But Im more interested in volume.
 
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