I suppose the purpose for your posts in this forum maybe to receive some input from others concerning your foray in this matter? Well, you left the door open; good or bad here's a thought.
Please understand that in automotive engine applications we generally concern ourselves first, with the oil viscosity requirements that are necessary for engine survivability when under-load (even maximum-load) and normal-operating-temperature (w/ considerations for excessive oil temperature - simultaneously), where it generally spends most of it's time. One doesn't ignore cold-start-up concerns, and yes, compromises especially in the northern regions during winter, are made, but keep in mind, typically most premature engine damage/failures take place with the engine in use under-load, often due to excessive load & heat. Notice that with the Coyote 5.0 in the mustangs today, Ford recommends a 5w-50 viscosity oil. The best compromise we can make is to reduce the load & operating R.P.Ms until some heat is generated in the oil. This is good practice in your old FE engine and you more modern units also.
Your often smaller modern engines are engineered with reduced oil clearances thru out, for a number of reasons (including E.P.A), therefore require thinner oils for proper lubrication. One of the biggest problems when the oil is cold, is their complicated (compared to the FE anyway) overhead cam valve train, which with tight clearances (didn't want the oil losses like the FE) and small and sometimes complicated routeings, (lets not forget some also have hydraulic valve timing functions), no camshaft bearings (cam runs in head, maybe not ideal bearing material?), those are probably the biggest concerns and reasons for the oil pressure step-up in your example.
Many engine builders will recommend (speaking solely of viscosity) a "lighter" oil for break-in; but this circumstance is intended as "break-in", low load, no over-heat, controled R.P.M.s, right?
I have already commented on my preference of filters and some of their attributes concerning bypassing function are mentioned elsewhere, and the H.V. oil pump is necessary with generous clearances, and I stated that understanding bypass values can be complicated, but also understand that the filter has less oil to contend with when the oil is cold if only (and it's not) due to the pumps inefficiency with the correspondingly cold oil.
The 10 p.s.i. per 1000 rpm formula works fine with this type of engine in this format, as with the greater size of the parts & oil clearances, the oil flow is achieved without the required higher pressure & due to the tighter clearances of you modern example. Note that if your oil delivery system is more efficient you can/will lower the pressure required; capitalizing on this, increasing efficiency & function on a number of fronts and make more power. Many racing engines operate in the range of approx. 5 p.s.i. per 1000 r.p.m..
And, lifters (old american V8 style) function better with higher viscosity (reasonable) oil as it is not displaced as easily. Scott.
Please understand that in automotive engine applications we generally concern ourselves first, with the oil viscosity requirements that are necessary for engine survivability when under-load (even maximum-load) and normal-operating-temperature (w/ considerations for excessive oil temperature - simultaneously), where it generally spends most of it's time. One doesn't ignore cold-start-up concerns, and yes, compromises especially in the northern regions during winter, are made, but keep in mind, typically most premature engine damage/failures take place with the engine in use under-load, often due to excessive load & heat. Notice that with the Coyote 5.0 in the mustangs today, Ford recommends a 5w-50 viscosity oil. The best compromise we can make is to reduce the load & operating R.P.Ms until some heat is generated in the oil. This is good practice in your old FE engine and you more modern units also.
Your often smaller modern engines are engineered with reduced oil clearances thru out, for a number of reasons (including E.P.A), therefore require thinner oils for proper lubrication. One of the biggest problems when the oil is cold, is their complicated (compared to the FE anyway) overhead cam valve train, which with tight clearances (didn't want the oil losses like the FE) and small and sometimes complicated routeings, (lets not forget some also have hydraulic valve timing functions), no camshaft bearings (cam runs in head, maybe not ideal bearing material?), those are probably the biggest concerns and reasons for the oil pressure step-up in your example.
Many engine builders will recommend (speaking solely of viscosity) a "lighter" oil for break-in; but this circumstance is intended as "break-in", low load, no over-heat, controled R.P.M.s, right?
I have already commented on my preference of filters and some of their attributes concerning bypassing function are mentioned elsewhere, and the H.V. oil pump is necessary with generous clearances, and I stated that understanding bypass values can be complicated, but also understand that the filter has less oil to contend with when the oil is cold if only (and it's not) due to the pumps inefficiency with the correspondingly cold oil.
The 10 p.s.i. per 1000 rpm formula works fine with this type of engine in this format, as with the greater size of the parts & oil clearances, the oil flow is achieved without the required higher pressure & due to the tighter clearances of you modern example. Note that if your oil delivery system is more efficient you can/will lower the pressure required; capitalizing on this, increasing efficiency & function on a number of fronts and make more power. Many racing engines operate in the range of approx. 5 p.s.i. per 1000 r.p.m..
And, lifters (old american V8 style) function better with higher viscosity (reasonable) oil as it is not displaced as easily. Scott.
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