Dry sump

Can someone please briefly explain what is a dry oil sump and what difference is it with a normal one? Advantages? Disadvantages? Thanks, Wael

Porsche explains: "Historically, 911 models have used a racing-derived lubrication system consisting of a large separate oil reservoir tank, a radiator-style oil cooler, and a shallow collection pan at the bottom of the engine. This combination was called a �dry sump� lubrication system, because no significant quantity of oil was stored in the sump beneath the crankshaft, making it relatively �dry.� The benefits of a dry sump include a lower center of gravity for the engine (since theoil pan is shallow, the engine can be installed lower down in the chassis), more effective cooling of the oil, and less tendency for the oil to be whipped into a froth by the whirling crankshaft. Autocross and hard-driving buffs also praised a dry sump�s resistance to �oil starving� an engine, as might occur in a conventional engine when the cornering forces of the car pulled the sump�s oil away from the oil pickup tube. Indeed the 911�s elaborate dry-sump oil system with its 13 quarts of oil was one of the car�s most distinctively race-like features, and helped make the nameplate legendary among sports-car enthusiasts. Today, the normally aspirated 911 and Boxster � as well as the Cayenne in a slightly varied form � employ a refined form of this system that achieves the same benefits, but with a more advanced technology. Porsche calls it an integrated dry sump. It�s a system that gathers and holds oil in a reservoir, integrated with the engine block. The oil is gathered and circulated by a total of three pumps: on the pressure side, a geared pump ensures the supply of oil, which returns to the reservoir from the crankshaft bearings, while oil in the cylinder heads is pumped back via two return pumps. The oil pickup is housed in the reservoir beneath a partition that prevents the oil from flowing to the sides under lateral acceleration by means of baffle plates. Oil is also, of course, filtered, while two �swirl pots� de-aerate the vital fluid. The primary difference between this integrated dry sump and an older 911�s pure dry sump is that the oil is stored in a carefully shaped separate reserve area at the bottom of the engine. Yet it is separated from the crankshaft and configured so as to prevent oil starvation and frothing. Overall, a smaller quantity of oil is required in this integrated design. An integrated sump does not need as many oil passages, thus reducing the volume of oil en route to and from the powerplant�s internally lubricated zones. Also, in today�s Porsche models, oil is a secondary cooling medium, not a primary cooling medium like it was in the past. The oil is not cooled by a separate radiator fed through hoses, but rather by a clever oil-to-water heat exchanging system. Carefully shaped oil passages in the engine run parallel to the coolant passageways � oil heat is thermally transferred to the coolant, where it�s dissipated by the main cooling radiators. This is not only simple and very effective, it also eliminates the weight, frontal area, and potential vulnerability of a separate oil radiator. And the parallel circuits help with engine temperature control: the coolant water heats quickly and helps bring the oil up to operating temperature soon after start-up. The Turbo, GT2 and GT3, due to their much higher power output, use a classic dry-sump system with a separate oil reservoir."

Beat me to it Viken......

It should perhaps be noted that from an engineering point of view the M96/01-03 engines are not dry sump, that's just marketing. Th M96/70 are of course dry sump in the technical sense. Cheers Uwe

Absolutely!

The oil pump in a normal engine is under the cranck i suppose and powered by the crank, now where is the oil pump in a dry sump and how does it work... Enquistive Waz

Waz, take a look at the page describing the GT3 oil supply on the Porsche web site - http://www2.uk.porsche.com/english/g.../oilsupply.htm