LS7 dry sump system supply pump function?
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On The Tree
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LS7 dry sump system supply pump function? If I understand correctly, the supply pump in the LS7 dry sump system draws oil from the tank, pressurizes it and pumps the oil throughout the engine. My question is: Does the supply pump actually suck the oil from the tank, or strictly rely on the oil getting to the fitting on the pan by gravity? It would seem that under extreme cornering conditions, gravity would tend to move oil away from the pan. Anybody know exactly how this works and, if it does actually suck the oil from the tank, how much suction does it have? 
Teching In
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the flow of oil from the tank to the pump will always be via suction. @ redline, alot of cars can pump oil fast enough to empty a coventional 5 qt oil in 7 seconds (or less)
to move this much oil via gravity, on a stationary car, you would probably need a 2 inch feed line, and gravity feed isnt going to do anything for you when centrifigal / linear force comes into play
suction in the line shouldnt be more then a few pounds, as your feeding the pump with a 10an (or larger) line, and the oil gally is what, 3/8 ? so 50 psi after the pump might equal -4psi in the line
to move this much oil via gravity, on a stationary car, you would probably need a 2 inch feed line, and gravity feed isnt going to do anything for you when centrifigal / linear force comes into play
suction in the line shouldnt be more then a few pounds, as your feeding the pump with a 10an (or larger) line, and the oil gally is what, 3/8 ? so 50 psi after the pump might equal -4psi in the line
On The Tree
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From: Odessa, TX
Dry sumping is not new technology. The idea is to scavenge the oil out of the motor just as fast as it pumps it in. This in return will always be putting in back in the tank and have enough oil in the tank to keep aqueate gravity pressure on the suction side. If you have ever had dealings with a dry sump you know that if the tank is high enough that in a matter of hours engine not running that 6 quarts of oil will run through the engine and the tank will be dry. Lets wait and see how long before someone with a LS7 runs one without oil because it has been sitting in storage.
I know how a the normal (for lack of a better word) Dry Sump system works. I just wanted to know how the LS7 specific system works. I can see the pump sucking the oil out of the tank and into the motor, but once it goes back to the pan, how does it get back into the tank. From the limited pics that ive seen of the system its hard for me to tell. I really got confused when I saw that the LS7 has an oil pickup tube in the pan.
On The Tree
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From: Odessa, TX
That is were it is "sucked" from is the pickup tube. The LS7 pan has a ramp from the pickup tube to the back of the pan. It alone probaly could not hold more than couple of quarts as this shrinks the volume dramatically inside the pan.
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On The Tree
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Thanks for answering my question. My main concerns are twofold.
First, if the supply line from the tank to the pan fitting is flat or slightly below the pan fitting and you are driving up a steep hill, will the supply pump have enough suction to pull the oil from the tank to the engine?
Second, if you change oil with the supply line from the tank fitting below the pan fitting (basically running uphill), will the engine be able to suck the oil through the empty supply line to the engine quickly enough so that the engine isn't starved for oil for a short time?
First, if the supply line from the tank to the pan fitting is flat or slightly below the pan fitting and you are driving up a steep hill, will the supply pump have enough suction to pull the oil from the tank to the engine?
Second, if you change oil with the supply line from the tank fitting below the pan fitting (basically running uphill), will the engine be able to suck the oil through the empty supply line to the engine quickly enough so that the engine isn't starved for oil for a short time?
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Teching In
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wardrum, as long as the car isnt on its roof, the engine will always have oil
any dry sump type oil pump has at least 2 stage's, one stage pumps the oil out of the pan and into the tank, the other stage draws oil out of the tank and sends it through the engine.
if the system uses more then 2 stages, the other pumps are used for additional functions, like running oil from the tank through a cooler and back to teh tank
a properly designed oil tank is cone shapped at the bottom so that oil doesnt slosh away from the pickup tube at the bottom, so youll always have oil going to the most important pump, the engine supply pump
if oil sloshes away from the pump between the pan & tank, no biggy, theres still 5+ quarts in the tank for the engine to run on
any dry sump type oil pump has at least 2 stage's, one stage pumps the oil out of the pan and into the tank, the other stage draws oil out of the tank and sends it through the engine.
if the system uses more then 2 stages, the other pumps are used for additional functions, like running oil from the tank through a cooler and back to teh tank
a properly designed oil tank is cone shapped at the bottom so that oil doesnt slosh away from the pickup tube at the bottom, so youll always have oil going to the most important pump, the engine supply pump
if oil sloshes away from the pump between the pan & tank, no biggy, theres still 5+ quarts in the tank for the engine to run on
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quick answer is that the oil is scavanged 2X as fast as it is pumped. the inside of the oil tank is designed to remove the air from the oil. the problems you are reffering to would be more of an issue with wet sump not dry sump. dry sump ensures that the oil pan stays with little to no oil and the tank stays full of oil.
