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Unread 08-23-2013, 08:37 AM   #16
laybackman
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Oil pressure is actually a measure of oil resistance. It is largely determined by clearances not flow. You have proved that point again.

Engine builders that know what they are doing make clearances a major priority. They plastigage every bearing journal twice. Once and then once more after spinning the crank a quarter turn.

Theoretically if you could close the oil system at say 40PSI, and keep the oil cool you would not need the oil pump. It is used to move the oil to the rad to be cooled only.

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Unread 08-23-2013, 05:39 PM   #17
BIGBADWOLF
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Quote:
Originally Posted by laybackman View Post
Theoretically if you could close the oil system at say 40PSI, and keep the oil cool you would not need the oil pump. It is used to move the oil to the rad to be cooled only.
????????????
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Unread 08-23-2013, 07:27 PM   #18
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Quote:
Originally Posted by BIGBADWOLF View Post
????????????
DO you have a problem with that statement? Why?
Oil lubricates forever if unchanged by heat or contaminates, correct?

Why move the oil if it doesn't need to be cooled/cleaned?

As long as it exists it lubricates doesn't it?

The only issue in reality is that you want to clean the oil occasionally, combustion being one item that does contaminate the oil. Wearing down of metallic parts also adds to that contamination since an engine is not, in reality, a perfect machine.

Theoretically if lubrication is perfect there is always a layer oil between all the moving parts.

My point was to stress the importance of correct clearances over the importance of very high oil pressure/flow.
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Unread 08-23-2013, 08:47 PM   #19
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Quote:
Originally Posted by laybackman View Post
DO you have a problem with that statement? Why?
Oil lubricates forever if unchanged by heat or contaminates, correct?

Why move the oil if it doesn't need to be cooled/cleaned?

As long as it exists it lubricates doesn't it?

The only issue in reality is that you want to clean the oil occasionally, combustion being one item that does contaminate the oil. Wearing down of metallic parts also adds to that contamination since an engine is not, in reality, a perfect machine.

Theoretically if lubrication is perfect there is always a layer oil between all the moving parts.

My point was to stress the importance of correct clearances over the importance of very high oil pressure/flow.
What do you mean, "It is used to move the oil to the rad to be cooled only."
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Unread 08-23-2013, 08:54 PM   #20
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Perfectly normal for a 4.0 even fresh motor. I build strokers out of my 4.0's. And the pressure is the same. Sounds Like you did a perfect job.
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Unread 08-24-2013, 06:27 AM   #21
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Quote:
Originally Posted by BIGBADWOLF View Post
What do you mean, "It is used to move the oil to the rad to be cooled only."
I meant base pan, unless he had an oil cooler.

When you are done critiquing my attempt to help the OP how about you jump in here and offer some constructive advice of your own.
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Unread 08-24-2013, 09:05 AM   #22
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Quote:
Originally Posted by laybackman View Post
I meant base pan, unless he had an oil cooler.

When you are done critiquing my attempt to help the OP how about you jump in here and offer some constructive advice of your own.
I have. Post#14. Sorry u perceived it as critiquing, I was just asking for clarification. Your statement was confusing,glad you cleared it up.
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Unread 08-24-2013, 09:54 AM   #23
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Quote:
Originally Posted by laybackman View Post
I meant base pan, unless he had an oil cooler.

When you are done critiquing my attempt to help the OP how about you jump in here and offer some constructive advice of your own.
I'm sorry, but your description is baffling to me too....
The oil pumps main purpose is to continuously replace the oil lost between bearing surfaces. since modern engines run on the "constant loss" principle, oil is constantly being forced out of the mating surfaces by various pressures. The pumps job is to constantly push more oil into the cavities, maintaining a continuous film of lubricant. Since there is very little clearance between the various surfaces, the pump will build pressure behind the main/rod bearings, cam, lifters and rockers. A relief valve controls the amount of pressure the pump maintains. Most oil pumps are relieved at around 40LBS (although this can vary). When the oil pressure goes down, this is usually a sign of wear (excessive clearance) in the system, most likely in the rod/main/cam bearings. A sign of this is the pressure varying with engine speed. this is because as the pump picks up speed, it is able to move more oil into the galley's, overcoming the excessive "leakage" in the system.

Many folks confuse pressure with volume when talking about modified pumps. High pressures do very little for you system, other than stress the cam gear. High volume, however is desirable (at least in my opinion), especially in slow speed, technical off road situations, where engine RPM's may be too low to adequately maintain pressure due to the pump's low rotational speed.
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Unread 08-24-2013, 06:05 PM   #24
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Originally Posted by jeepdaddy2000 View Post
I'm sorry, but your description is baffling to me too....
The oil pumps main purpose is to continuously replace the oil lost between bearing surfaces. since modern engines run on the "constant loss" principle, oil is constantly being forced out of the mating surfaces by various pressures. The pumps job is to constantly push more oil into the cavities, maintaining a continuous film of lubricant. Since there is very little clearance between the various surfaces, the pump will build pressure behind the main/rod bearings, cam, lifters and rockers. A relief valve controls the amount of pressure the pump maintains. Most oil pumps are relieved at around 40LBS (although this can vary). When the oil pressure goes down, this is usually a sign of wear (excessive clearance) in the system, most likely in the rod/main/cam bearings. A sign of this is the pressure varying with engine speed. this is because as the pump picks up speed, it is able to move more oil into the galley's, overcoming the excessive "leakage" in the system.

Many folks confuse pressure with volume when talking about modified pumps. High pressures do very little for you system, other than stress the cam gear. High volume, however is desirable (at least in my opinion), especially in slow speed, technical off road situations, where engine RPM's may be too low to adequately maintain pressure due to the pump's low rotational speed.
I am well aware of how the oil system works in an internal combustion engine. Oil doesn't get 'lost', it gets circulated because the system is designed to continuously pump the oil to through the system, kind of like the cooling system.

Theoretically (that term has been used already) the engine could stay lubed with a closed pressurized system if the oil could stay cool and clean enough. That is too expensive to implement and hurts the oil dudes too much also.
The oiling system on a car is rudimentary. Maintain certain clearances and keep pumping oil through it.

Ok back on topic if that is possible.
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Unread 08-30-2013, 02:54 AM   #25
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I guess my 2.5L is pretty healthy then.
18,000 miles
Melling high volume oil pump
Rotella T6 5w40
STP oil treatment

My oil pressure numbers are-
-Idle Cold - 71psi. (Cold = 30f)
-Run Cold - 78-90psi
---
-Idle Warm - 55-62psi (warm= 70-80f)
-Run Warm - 64-70psi
---
-Idle Hot - 40-43psi (hot = engine oper temp)
-Run Hot - 63-66psi)

Been that way since we rebuilt the motor. :-)
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Unread 08-30-2013, 01:08 PM   #26
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Originally Posted by Flyordie View Post
I guess my 2.5L is pretty healthy then.
18,000 miles
Melling high volume oil pump
Rotella T6 5w40
STP oil treatment

My oil pressure numbers are-
-Idle Cold - 71psi. (Cold = 30f)
-Run Cold - 78-90psi
---
-Idle Warm - 55-62psi (warm= 70-80f)
-Run Warm - 64-70psi
---
-Idle Hot - 40-43psi (hot = engine oper temp)
-Run Hot - 63-66psi)

Been that way since we rebuilt the motor. :-)
Why would you want that high of a pressure???? HV pump is overkill especially on a 2.5. All that does is take hp away from the drivetrain and puts stress on the cam. Its a psych thing.
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Unread 08-30-2013, 03:54 PM   #27
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Originally Posted by BIGBADWOLF View Post
Why would you want that high of a pressure???? HV pump is overkill especially on a 2.5. All that does is take hp away from the drivetrain and puts stress on the cam. Its a psych thing.
Its a carbed motor. We bored and stroked it to 2.7L. Forged crank, rods and pistons. We just had some free time and went all out. HV pump was to make sure the motor was lubricated well due to the tight tolerances. (We were pushing 9.8:1 comp ratio)

When we threw it on the dyno it was 130-135hp and 172-185ft-lb torque.
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Unread 08-30-2013, 08:18 PM   #28
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Originally Posted by BIGBADWOLF View Post

Why would you want that high of a pressure???? HV pump is overkill especially on a 2.5. All that does is take hp away from the drivetrain and puts stress on the cam. Its a psych thing.
I agree. It just makes you feel better. In the long run you'll be fixing seals and too many other important parts.
I do like what you did otherwise.
I build stroker's out of 4.0's. Never used or needed HIV pumps.
Save that stuff for dragsters
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Unread 08-30-2013, 08:49 PM   #29
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Engine oil pressure has NOTHING to do with seal life.

4.0s did indeed use HV oil pumps in some applications for the military.

And what other important parts can be damaged by higher oil volume?
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Unread 08-30-2013, 09:13 PM   #30
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And what other important parts can be damaged by higher oil volume?
The pump itself when it runs dry because most of the oil is being pumped to the top of the engine faster than it can drain back to the sump.
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