LS3 Oil Path
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Drifting
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LS3 Oil Path
On an LS3 engine. How does the oil flow from bottom to top end? I assume it's oil pickup, then oil filter, then main and cam bearings, then the top end via pushrods, and then it flows down from cylinder head drainage holes back down to oil pan?
Le Mans Master
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Melting Slicks
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Main bearings, cam bearings, and top end are all fed in parallel, not top end after main and cam bearings. As you can see in the sketch above, everything is fed from a common galley, so no one component has priority over another. I see nothing wrong with this system, though. When the engine is shut down, most of the oil in the galley stays there and will resupply all of the engine components as soon as it starts up again.
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Drifting
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Main bearings, cam bearings, and top end are all fed in parallel, not top end after main and cam bearings. As you can see in the sketch above, everything is fed from a common galley, so no one component has priority over another. I see nothing wrong with this system, though. When the engine is shut down, most of the oil in the galley stays there and will resupply all of the engine components as soon as it starts up again.
So does the oil in the valve cover area flow downhill into the rod bearings or back into the oil pan?
Per the diagram it appears that way but that wouldn't make sense. It would need oil pressure to do that and since the oil at the top of the valve cover area, it is no longer under pressure, so I would have to flow down back into the pan via gravity.
Last edited by Pettrix; Feb 5, 2025 at 04:09 PM.
Le Mans Master
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From: West coast CA
So does the oil in the valve cover area flow downhill into the rod bearings or back into the oil pan?
Per the diagram it appears that way but that wouldn't make sense. It would need oil pressure to do that and since the oil at the top of the valve cover area, it is no longer under pressure, so I would have to flow down back into the pan via gravity.
Per the diagram it appears that way but that wouldn't make sense. It would need oil pressure to do that and since the oil at the top of the valve cover area, it is no longer under pressure, so I would have to flow down back into the pan via gravity.
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Drifting
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Le Mans Master
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Race Director
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this may help, video I made of the barbell a while back. You can at least visualize the first half of the oiling system
And ALL of the bearings need pressurized oil, not leftover gravity oil from the rocker arms. All spillover from rockers, pistons, bearings drips back down into the pan to be recovered, pumped and filtered back through the system again
And ALL of the bearings need pressurized oil, not leftover gravity oil from the rocker arms. All spillover from rockers, pistons, bearings drips back down into the pan to be recovered, pumped and filtered back through the system again
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As the oil is spraying out from the pressurized circuits, gravity field begins to pull it back to the pan. When you shut the engine off this fraction gradually makes its way to the pan via gravity. Without gravity, it would not seek the oil pan, merely cling to surfaces and itself, and go towards any flowing exits such as the PCV system.
That is, gravity and the PCV system discuss who gets to have some oil. If gravity was not present, there would be only oil entering the PCV system and none going to the pan.
Oil will go places when energy is provided to move it, such as gravity. PCV uses pumping action from some kind of pump to provide energy to drive flow, the engine is a pump and it can provide that energy, or an external pump like dry sump or turbocharger could be used instead as a source of energy to drive fluid flow. All OEM vehicles with turbos use the turbo as energy source to drive PCV flow at wot for example, its a couple percent of engine power that an natural aspirated engine gives up if they want to drive actual PCV flow at WOT.
The esoteric nature of oil in PCV flow is the influence of pressure on oil droplet radius and density in a field of gravity
High crankcase pressure suspends higher oil droplet density and radius which is pulled into the PCV system
That is, gravity and the PCV system discuss who gets to have some oil. If gravity was not present, there would be only oil entering the PCV system and none going to the pan.
Oil will go places when energy is provided to move it, such as gravity. PCV uses pumping action from some kind of pump to provide energy to drive flow, the engine is a pump and it can provide that energy, or an external pump like dry sump or turbocharger could be used instead as a source of energy to drive fluid flow. All OEM vehicles with turbos use the turbo as energy source to drive PCV flow at wot for example, its a couple percent of engine power that an natural aspirated engine gives up if they want to drive actual PCV flow at WOT.
The esoteric nature of oil in PCV flow is the influence of pressure on oil droplet radius and density in a field of gravity
High crankcase pressure suspends higher oil droplet density and radius which is pulled into the PCV system
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As the oil is spraying out from the pressurized circuits, gravity field begins to pull it back to the pan. When you shut the engine off this fraction gradually makes its way to the pan via gravity. Without gravity, it would not seek the oil pan, merely cling to surfaces and itself, and go towards any flowing exits such as the PCV system.
That is, gravity and the PCV system discuss who gets to have some oil. If gravity was not present, there would be only oil entering the PCV system and none going to the pan.
Oil will go places when energy is provided to move it, such as gravity. PCV uses pumping action from some kind of pump to provide energy to drive flow, the engine is a pump and it can provide that energy, or an external pump like dry sump or turbocharger could be used instead as a source of energy to drive fluid flow. All OEM vehicles with turbos use the turbo as energy source to drive PCV flow at wot for example, its a couple percent of engine power that an natural aspirated engine gives up if they want to drive actual PCV flow at WOT.
The esoteric nature of oil in PCV flow is the influence of pressure on oil droplet radius and density in a field of gravity
High crankcase pressure suspends higher oil droplet density and radius which is pulled into the PCV system
That is, gravity and the PCV system discuss who gets to have some oil. If gravity was not present, there would be only oil entering the PCV system and none going to the pan.
Oil will go places when energy is provided to move it, such as gravity. PCV uses pumping action from some kind of pump to provide energy to drive flow, the engine is a pump and it can provide that energy, or an external pump like dry sump or turbocharger could be used instead as a source of energy to drive fluid flow. All OEM vehicles with turbos use the turbo as energy source to drive PCV flow at wot for example, its a couple percent of engine power that an natural aspirated engine gives up if they want to drive actual PCV flow at WOT.
The esoteric nature of oil in PCV flow is the influence of pressure on oil droplet radius and density in a field of gravity
High crankcase pressure suspends higher oil droplet density and radius which is pulled into the PCV system
Drifting
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apologies for the one year bump - does all the fluid flow through the cooler? i.e. if the cooler is undersized, will it starve the system? Or will it bypass via some other pathway? Wondering how the thermostat coolers get around this? Do they have two parallel paths to the outlet?
Drifting
Joined: Dec 2016
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Okay - havent found an answer but I believe the OEM cooler is indeed a whole-flow cooler. All the fluid passes through the filter, then through the cooler, then back into the engine.
Aftermarket thermostatic units can apparently be spec’d to not pass the entire amount of oil flow.
If anyone has more info/better input, please update.
*edit*
talked a bunch with improved racing rep. I think ill go with their corvette specific cooler, mounted to the foglight area. going to see what my temps look like in normal driving first.
Aftermarket thermostatic units can apparently be spec’d to not pass the entire amount of oil flow.
If anyone has more info/better input, please update.
*edit*
talked a bunch with improved racing rep. I think ill go with their corvette specific cooler, mounted to the foglight area. going to see what my temps look like in normal driving first.
Last edited by Ahrmike; Jan 25, 2026 at 05:05 AM.