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Re: High volume oil pump?
[Re: ONEBADBIRD]
#221898
02/12/09 10:12 AM
02/12/09 10:12 AM
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Joined: Jan 2003
Posts: 2,936
Richmond, VA
VT_Dart
master
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master
Joined: Jan 2003
Posts: 2,936
Richmond, VA
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Many where will argue, but you should be fine. If you think about it, the pump won't be pumping any more oil most of the time. Most Mopars I've had run on the oil pressure relief spring (70-75 psi) almost all of the time while driving. Pressure and flow are directly related, ie the same engine will flow the exact same amount of oil so long as the pressure is exactly the same. If a pump is trying to put more oil into the engine, the pressure will go up (think about blowing harder and harder through a straw), and once it hits the relief point that extra oil is just bypassed. So... when you're under the relief spring pressure the high volume will be pumping more oil, but once you start riding that spring the amount of oil actually reaching your engine will be the same.
Like I said, some others will argue but it's pretty simple flow principles. Oh yeah, and I run a high-volume with a stock pan lol.
Darrah Heath
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Re: High volume oil pump?
[Re: ONEBADBIRD]
#221900
02/12/09 05:46 PM
02/12/09 05:46 PM
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Joined: Jan 2003
Posts: 25,808
Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,808
Rio Linda, CA
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If the current oil pressure is sufficient, the HV pump isn't an "upgrade", it's merely a change and will actually rob a little power.
The INTERNET, the MISinformation superhighway
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Re: High volume oil pump?
[Re: NTOLERANCE]
#221903
02/12/09 07:48 PM
02/12/09 07:48 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
The achillies heel of the HV pump and stock pan and pick up is when RPMS increase significantly, the pan can get sucked dry.
Although I have never had a pan get sucked dry, even at 6500 rpm.  Then again maybe it has and I never knew it...... 
This is absolutely not true. At the same pressure and rpm on the same engine, a high volume pump will put exactly the same amount of oil to the engine as a stock pump, and that same amount out of the pan. The "suck the pan dry" theory has been around for years, but has been untrue for all those years.
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Re: High volume oil pump?
[Re: ONEBADBIRD]
#221904
02/12/09 07:52 PM
02/12/09 07:52 PM
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Joined: Jan 2009
Posts: 85
Rhode Island
GoodfellaHenry70
member
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member
Joined: Jan 2009
Posts: 85
Rhode Island
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You can't go wrong with a high volume(not high pressure) oil pump. I use a Milodon. Do Not Forget to replace the stock shaft with a HD Hardened Input Shaft. Cheap Insurance. 
"No big deal...It's called Advanced Dilusionary schizophrenia with involuntary narcissistic rage."
Just call me Hank.
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Re: High volume oil pump?
[Re: NTOLERANCE]
#221906
02/12/09 08:17 PM
02/12/09 08:17 PM
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Joined: Jan 2003
Posts: 14,610
Not2farfromNashville, TN
Rug_Trucker
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,610
Not2farfromNashville, TN
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Been running an HV pump for close to 200K on my 360. No special shaft, never sucked the pan dry. Of course it is 6 1/2 qts stock and usually never sees anything over 4400 rpm.
"The only thing to do for triumph of evil is for good men to do nothing"
"NUNQUAM NON PARATUS!"
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Re: High volume oil pump?
[Re: John_Kunkel]
#221907
02/12/09 08:22 PM
02/12/09 08:22 PM
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Joined: Oct 2007
Posts: 1,973
SoCal
jake4cars
top fuel
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top fuel
Joined: Oct 2007
Posts: 1,973
SoCal
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Quote:
If the current oil pressure is sufficient, the HV pump isn't an "upgrade", it's merely a change and will actually rob a little power.
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Re: High volume oil pump?
[Re: NTOLERANCE]
#221908
02/12/09 08:30 PM
02/12/09 08:30 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
Quote:
This is absolutely not true. At the same pressure and rpm on the same engine, a high volume pump will put exactly the same amount of oil to the engine as a stock pump, and that same amount out of the pan. The "suck the pan dry" theory has been around for years, but has been untrue for all those years.
The reasons for concern with a HV pump and a stock pan are real....if you do suck the pan dry at 7000, how long do you think the bearings will last? And we havent even discussed the MP windage tray holding all the oil out of the pan. Weather or not its an old wives tale, it HAS to be considered.
As I stated before, I havent sucked a stock pan dry even at 6500. But if the risk of having no oil at your main and rod bearings at redline isnt an "Achilles heel" I dunno what is.
If you are going to suck the pan dry with a high volume pump, you will also suck it dry with a standard pump, if you have the same engine and oil pressure. It is simple physics and hydraulics. Do a search on it, and you will find all kinds of technical information showing why it doesn't suck the pan dry, but it all boils down to the fact that the extra oil just goes through the pump bypass because the engine will only take the amount of oil the resistance to flow and pressure dictate. Pump flow does not enter the equation.
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Re: High volume oil pump?
#221909
02/12/09 08:31 PM
02/12/09 08:31 PM
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Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Quote:
This is absolutely not true. At the same pressure and rpm on the same engine, a high volume pump will put exactly the same amount of oil to the engine as a stock pump, and that same amount out of the pan. The "suck the pan dry" theory has been around for years, but has been untrue for all those years.
How do you figure that? Per revolution the HV pump is pumping more oil than a standard pump. The excess goes out the pressure bypass. More is being pumped out of the pan, but it's cycling right back into it. Some claim the worry is that if your engine clearances are nice and tight and if your bypass valve cannot flow enough oil. you run the possibility of running oil pressure over 75psi, in which case you would displace more oil from the pan to the bearings, etc. But IMO the bypass valve is up to the task.
In reality I think the HV pumps were developed as a band-aid to engines with worn/loose bearing clearances to maintain an acceptable amount of oil pressure.
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Re: High volume oil pump?
[Re: DaytonaTurbo]
#221910
02/12/09 08:40 PM
02/12/09 08:40 PM
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Joined: Nov 2007
Posts: 21,825
Kirkland, Washington
Pacnorthcuda
Too Many Posts
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Too Many Posts
Joined: Nov 2007
Posts: 21,825
Kirkland, Washington
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Quote:
Quote:
This is absolutely not true. At the same pressure and rpm on the same engine, a high volume pump will put exactly the same amount of oil to the engine as a stock pump, and that same amount out of the pan. The "suck the pan dry" theory has been around for years, but has been untrue for all those years.
How do you figure that? Per revolution the HV pump is pumping more oil than a standard pump. The excess goes out the pressure bypass. More is being pumped out of the pan, but it's cycling right back into it. Some claim the worry is that if your engine clearances are nice and tight and if your bypass valve cannot flow enough oil. you run the possibility of running oil pressure over 75psi, in which case you would displace more oil from the pan to the bearings, etc. But IMO the bypass valve is up to the task.
In reality I think the HV pumps were developed as a band-aid to engines with worn/loose bearing clearances to maintain an acceptable amount of oil pressure.
Agreed. TO add to this, IF an engine is 'loose' and the result on an HV pump IS higher oil pressure, then more oil is being pumped through the engine (faster) and the pan CAN be sucked dry. Its happened to me on a loose motor/HVpump/stock pan.
If the same pressure results from either pump (on a given engine) then the excess is being dumped back into the pan and the only downside is an increase in parasitic power loss.
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Re: High volume oil pump?
[Re: Pacnorthcuda]
#221912
02/12/09 08:52 PM
02/12/09 08:52 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Actually, the bypass oil isn't dumped back into the pan, it goes back to the inlet inside the pump, but the effect is the same.
If you have a huge pump and tight engine, you can overload the bypass and climb the pressure, as you said, but then you use more oil through the engine because of the raised pressure it causes. If the pressure doesn't change, the oil flow doesn't change. I have found many new pumps lately to not be of very good quality. I tested a new Melling high volume out of the box, and it flowed less than an old OEM standard pump. The reason was excessive cover clearance and steps in the bottom of the pump housing. When I fixed the problems it picked up 25% in flow. The bypass on the same pump had casting flash over nearly 1/3 of the bypass opening, so it could have beena problem once the pump volume was returned to what it should have been.
I will not put in any new pump until I check the clearances and finishes in it. Most are very bad, and probably explain why a bunch of new engines show low oil pressure. If your stock volume pump is only putting out 75% of what is supposed to, you will be low on pressure at idle.
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Re: High volume oil pump?
[Re: Pacnorthcuda]
#221915
02/12/09 09:16 PM
02/12/09 09:16 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Small block recircs within the pump also.
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Re: High volume oil pump?
#221916
02/12/09 09:44 PM
02/12/09 09:44 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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I have heard of alot of purported failures with Melling hi vol pumps(SB's) so be sure & open it up & check clearances/clean it which should be done on any part & as mentioned there are alot of areas that can be ported. I personally dont think a pan can be sucked dry only that the pickup can become uncovered & on a high rpm eng I make sure the pickup/pan clearance is 1/8"-1/4". I think inadequate clearance there will starve an(high rpm) eng quicker than anything. I would think that the vol is going to max out at a certain PSI(maybe when the bypass psi is reached(or even before)) but I have spoken with some highly skilled eng builders who do swear by a hi vol.
live every 24 hour block of time like it's your last day on earth
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