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Oil Pressure, Too Much??

JG71B

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Running a stock 78 400 4bbl motor with 57k miles. Everything looks perfect inside. Just got it fired up the other day for the first time since getting it. Wix filter and 20 w50 (didn't realize it wasn't 10w 40 until I was home) VR1 oil. Cold she hit 80lbs, once she hot between 40 and 50. Is that too high of pressure? change to 10w 40 or is the 20w 50 ok for now? Thanks!
 
Where my 383HP Bee runs hot on 10W30. Engine that was rebuilt in 1978!
beecruisejune62021 004.JPG
 
I think you are good. Every engine is different depending on the tolerances. I have one Hemi that is 85-90 cold and 60-70 warmed up and no lower than 50 idling at 185 degrees. No problems with 10K miles on the build.
 
I was running 20/50 hi-zinc racing oil in my rebuild and pressure was always pretty high even when hot. I switched to 10/30 and pressure came down - the reason I switched though was also due to engine heat...reading up on higher vis oils retaining more heat. No clue if that made a diff since I had already done some other things to lower temp. Articles on oils referenced lower vis oils for street driving...higher for racing...seems as though your getting good range so just my two pennies.
 
Other than waisting the hp to build unnecessarily high oil pressure I don't know what it would hurt?
 
Other than waisting the hp to build unnecessarily high oil pressure I don't know what it would hurt?
I guess every little bit counts as there isn't much hp to start with lol
 
Heck my old 76 motor home 440 is 75lbs cold,
190 degrees its 30 at idle and 55/60 at speed.
15 - 40 Rotella
 
excessive pressure eventually eats up the intermediate shaft bushing. people have to learn this the hard way.
 
Well thanks for the breakdown on how that works....

Ran good 20-50 in every mopar I've owned before switching to Rotella 15w-40 and I've never had a problem. Stock shafts are garbage. I always installed a good Melling pump and a hardened/pinned shaft.
 
Cold pressure is only a measurement of resistance to unwarmed oil. 40-50 hot on a street motor is fine.
Doug
 
when the 440 in my '68 Charger was rebuilt, the machinist told me to run Valvoline 20/50. It would peg an 80 lb oil gauge all day. Ran it for 60,000 miles like that.
 
Referring to my earlier post on why I swapped over to a lower vis racing oil, here are a couple of excerpts here from a 50 page study on motor oils:
…many folks believe that oil pressure = lubrication, but that is simply NOT the case. Pressure is only a measurement of resistance to flow. But, oil FLOW is lubrication, and you get more flow with thinner oil as we just saw above. Lubrication is what is used to separate moving parts, and keep them from making metal to metal contact, which results in wear/damage. And increased flow also has another very important advantage. An engine’s vital internal components are all DIRECTLY OIL COOLED, but only INDIRECTLY water cooled. And thinner oil will flow more freely, carrying away more heat, thus providing better cooling for those vital internal components. And of course that extra cooling is even more important in high performance engines. So, going to the trouble of achieving almost an extra 20% in flow, is well worth the effort. If someone asks why use a high volume pump, the answer is so that you can maintain reasonable oil pressure with thinner oil. And with thinner oil, you can improve both lubrication and cooling. Reduction of 5 to 10 HP can be caused by higher-vis oils.
Here are some comparison numbers from an 830 HP road race engine, on the track:

15W50 oil = 80 psi = 265* oil temp............5W20 oil = 65 psi = 240* oil temp

The thicker oil flowed more slowly through the bearings, thus getting hotter and driving up bearing temps. If an engine is running hot, use a thinner oil to increase flow and increase cooling. And running a high volume oil pump allows you to do that. ...the “Ideal Lubrication Setup” for most traditional engines, is a high volume/high pressure oil pump with a thinner multi-viscosity motor oil

Thicker oil does not automatically provide better wear protection than thinner oils. Extensive “dynamic wear testing under load” of dozens and dozens of motor oils, has shown that the base oil and its additive package “as a whole”, is what determines an oil’s wear protection capability, NOT its viscosity. So, don't run thicker oil under the false assumption that it can provide better wear protection for our engines.

•BOTTOM LINE: Thinner oils are better for most engine lubrication needs.


Notable source of wear is due to cold start up and my ride can sit for a couple weeks without running it and longer in the winter despite being in a heated garage. Seems that faster flowing oil is a better thing.
 
Referring to my earlier post on why I swapped over to a lower vis racing oil, here are a couple of excerpts here from a 50 page study on motor oils:
…many folks believe that oil pressure = lubrication, but that is simply NOT the case. Pressure is only a measurement of resistance to flow. But, oil FLOW is lubrication, and you get more flow with thinner oil as we just saw above. Lubrication is what is used to separate moving parts, and keep them from making metal to metal contact, which results in wear/damage. And increased flow also has another very important advantage. An engine’s vital internal components are all DIRECTLY OIL COOLED, but only INDIRECTLY water cooled. And thinner oil will flow more freely, carrying away more heat, thus providing better cooling for those vital internal components. And of course that extra cooling is even more important in high performance engines. So, going to the trouble of achieving almost an extra 20% in flow, is well worth the effort. If someone asks why use a high volume pump, the answer is so that you can maintain reasonable oil pressure with thinner oil. And with thinner oil, you can improve both lubrication and cooling. Reduction of 5 to 10 HP can be caused by higher-vis oils.
Here are some comparison numbers from an 830 HP road race engine, on the track:

15W50 oil = 80 psi = 265* oil temp............5W20 oil = 65 psi = 240* oil temp

The thicker oil flowed more slowly through the bearings, thus getting hotter and driving up bearing temps. If an engine is running hot, use a thinner oil to increase flow and increase cooling. And running a high volume oil pump allows you to do that. ...the “Ideal Lubrication Setup” for most traditional engines, is a high volume/high pressure oil pump with a thinner multi-viscosity motor oil

Thicker oil does not automatically provide better wear protection than thinner oils. Extensive “dynamic wear testing under load” of dozens and dozens of motor oils, has shown that the base oil and its additive package “as a whole”, is what determines an oil’s wear protection capability, NOT its viscosity. So, don't run thicker oil under the false assumption that it can provide better wear protection for our engines.

•BOTTOM LINE: Thinner oils are better for most engine lubrication needs.


Notable source of wear is due to cold start up and my ride can sit for a couple weeks without running it and longer in the winter despite being in a heated garage. Seems that faster flowing oil is a better thing.
well stated and the truth!!!!!
 
All that extra heat that the thinner oil is carring away, where does it go? And how does it get there?
 
All that extra heat that the thinner oil is carring away, where does it go? And how does it get there?
Fantastic question. It gets routed through the heater core.
 
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