Browse around some forums on the net and you’d think that dry-sumps were sent from hell to complicate the lives of car fans. It’s stupid they say. Why would you want to complicate your lubrication path they say.
Let’s see what dry-sumping a car is all about and find out why you’d bother.
In a normal or, wet-sump, engine, the oil that lubricates the bearings and internals is pumped through the engine and then gravity calls it “home” to the sump underneath the crankcase.
On a dry-sumped engine, the oil-pan is not underneath the engine. Rather there is an externally placed oil tank elsewhere. Usually this is put wherever there was room left on the car when the car maker built the thing, lol.
A pump takes this oil from the tank to the bearings and also to a second pump (called a scavenge pump) which pumps the oil back to the external oil tank after it’s been through the process of lubricating the engine internals.
Why replace gravity with 2 sets of pumps though? Sounds like just extra stuff to go wrong, right?
There’s a couple of good solid reasons to go through the effort of dry-sumping.
The first is to do with motorsport. During extremely hard cornering, the centrifugal forces acting on the oil inside the oil-pan of a traditional wet-sump engine, can drive the oil away from the pickup point in the sump. This results in the engine sucking air instead of lubricant. As you can imagine, the results are not pretty, with many an engine going “kaboom!” from overheating.
The second reason is a simple one of packaging. By moving the oil-pan away from the bottom of an engine, you make it more compact. You can effectively put the engine into a smaller space and put your oil tank somewhere more convenient to the shape of your car. It can also benefit with weight distribution.
There’s also the (maybe) minor performance increase of not having your crankshaft having to move through the oil in the sump(known as windage) in some engine configurations.
Apart from the extra pump and the plumbing to and from it, there’s really no downsides to dry-sumping. It’s kind of surprising that it’s not a more commonly done thing in current vehicles.
Michael Adams from Test Driven Australia
Article originally written for Infinite-Garage