dry sump

[pgarner]

can anyone clarify for me what is a dry sump

as far as i can tell its basically no oil in the base of the oil the oil is cirulated around the engine as standard but nowhere for it to sit

how does this help preformance ? apart from the weight savings of less oil no sump

[waynne]

Pros
The engine can sit lower. The crank is not splashing around in oil and oil pressure is reached much sooner due to the more efficient pump.

Cons
You have to ensure the correct amount of oil is there every 200 miles or so. Long journeys mean you top up the oil. Less oil means it loses its lubricity more quickly so oil changes are more frequent. Oil helps cool the engine so some of the cooling effect is lost as less oil means it is in contact with the hot parts of the engine more often.

Most sports cars have dry sumps as they are typically lowered to the point a sump would start dragging. This is particularly true of kit cars etc...

[old-git]

Hi Waynne

Sorry to contradict you, but I don't think that you quite understand about dry sumps.

The major difference between a wet and dry sump is where the oil is stored. In a wet system, it is kept in the sump under the engine. This is simple cheap and convenient. However, as you say, one of the downsides is that the crank is splashing around in it, sapping power. This can be alleviated to a great extent by fitting a windage tray. This is a sheet of steel that is cut to fit close to the crank separating the oil from the crank.
Another problem with the wet sump is oil surge under acceleration and cornering where there is a risk of the oil pickup being starved of oil. This, again, can be alleviated by fitting baffles, but it is not ideal.

A dry sump is a system where the oil is stored remote from the engine. It has two oil pumps, usually built into one unit. One scavenges the oil from a small collecting area built into the dry sump under the crank and pumps it to a remote tank. A second pump returns the oil to the engine.

The advantages of the dry system are many. No power loss due to the crank running in it. No risk of the oil pickup running dry due to acceleration or cornering. More oil can be stored allowing for greater control of temperatures. Th oil can, if required, be run though a remote oil cooler. Oil pressure can be greater, but too much pressure is almost as bad as too little!

The is no need to check the oil any more often than with a wet system. Oil changes are no more frequent than with the wet sump system.

Dry sump systems are the best but expensive. A typical system for a Ford Zetec will cost you around £850 from Burton's.

[waynne]

That told me eh! I was convinced there was less oil in a dry sump - ah well, maybe I don't know everything !

Thanks for the heads up - now I know a little more about them. They actually sound like a good idea now.

[HDi fun]

I seem to remember Porsche's 959 (1987) having a dry sump. The reviewers in CAR magazine made a big thing about it back then.

One of the best performance cars ever made. And, no, it's not a bloody diesel!