WW goes with LS7 Dry sump Setup

[ECSRacingAdmin]

Well as many of you have read we have decided to utilize GM’s newest and meanest powerplant the LS7 to rocket the Millennium Falcon around the toughest road courses in the area. But why did we decide to use the LS7 you ask? Well besides the fact that the number 427 fits perfectly next to the name Corvette the main reason to go with the LS7 for a road racing application over another LSx setup is that Gm engineers have produced a stock production working dry sump oiling system for the LS7 where you will not lose you’re a/c. Most dry sumps are belt driven and for the corvette all the systems we saw needed to be mounted where the a/c compressor is. The LS7 dry sump pump is not belt driven and runs off of the crankshaft by a sprocket or gear drive setup. Since the pump will still be located under the front cover it allows us to still use the stock accessories on Bob’s car which includes the air conditioning.

So what is a wet sump?

First let’s talk about the “wet” sump. A sump is described as a low lying area or container that collects unwanted or excess liquids. Many of you have a sump pump in your house and know that when the basement floods the water is directed to a pit or sump and an electric pump pumps the water out. Well the sump on an engine is mainly called an oil pan. The pan, which is bolted to the bottom side of the engine, acts as a reservoir housing the engines excess oil. A pan can hold from 4 to 20 quarts depending on size and application. The oil is stored in the pan where an oil pickup tube is located near the bottom. The pickup tube attaches to the oil pump and supplies the pump with oil that will be sent to the moving parts of the engine. Once the oil passes through the engine under pressure from the pump, gravity takes over and the oil drips down and back into the pan. The oil collects in the pan and then it is sucked up again by the oil pump and sent back into the moving parts of the engine.

So what’s a dry sump?

Well a dry sump works off of the same oiling principle as the wet sump meaning that a pump supplies oil to the engine and a sump or pan collects it. The major difference is that the oil is stored in a separate container or tank, not in the oil pan. The separate tank is mounted somewhere next to the engine in the car. A typical dry sump tank can hold 10 to 20 quarts of oil. A dry sump system generally uses an external belt driven pump mounted to the side of the engine that has various “stages” built into it. The first stage is the pressure stage. It is the part of the pump that pulls oil from the bottom of the dry sump tank and sends it into the engine. The other stages are called the scavenge, which a pump can have from 1 to 5 scavenge stages. The scavenge stage basically sucks the used oil out of the engine and back to the tank. Each stage connects to a different place on the engine, usually 2 to 3 lines going to the bottom of the oil pan and on certain engines a line connecting to the valley below the intake manifold. Basically the scavenge stages of the pump keeps the oil out of the oil pan and stored in the tank. This is how the term “Dry” sump was named.

So what are the advantages of the dry sump over the wet sump setup?

The major reason a wet sump setup is not generally used in a racing application is because of the high probability of oil starvation to the pump. Because of the lateral forces caused by road racing the oil can have the tendency to run up the sides of the oil pan or away from the pickup. If the pickup runs dry on oil, even if only for a split second, the oil pressure in the engine can drop causing internal part failures. The dry sump greatly aides in the prevention of oil starvation because of the oil being stored in a larger separate tank, almost always containing enough oil for the pump to use. Other benefits of a dry sump is a good working system will pull a vacuum on the crankcase from the scavenge stages pulling oil out of the engine. That vacuum created can help piston ring seal and cut down on engine blow by. Also being that the oil is stored in a separate tank it has a better ability of staying cooler since it is stored away from the hot moving parts of the engine. The dry sump greatly eliminates aeration of the oil as compared to the wet sump setup. When the oil is stored in the wet sump pan it is prone to splash or being whipped from hitting the internal moving parts of the engine. “Whipping” of the oil creates higher temperature, along with aeration and loss in horsepower. Also a greater amount of oil can be ran in a dry sump, the stock corvette can hold 7 quarts race ready. The dry sump tank that will be utilized for bob will hold 12 quarts of oil. So why can’t you put 12 quarts in your wet sump? Following correct oil level amount in a wet sump is extremely important. An overfill situation will cause the oil level to be too high causing the oil to be whipped by the crankshaft. An under fill situation will make it easier for the oil pump to run away or run dry of the oil in the pan.

So I guess it would be safe to say that both Bob and his oil will stay cool with this setup!