Pilot135R

Hello All,

Please explain the difference between a wet sump and a dry sump. What are the advantages and disadvantages of each type?

Thanks!
Bobby

LoneWarrior2552

ColdSmoke

http://auto.howstuffworks.com/question331.htm

LS6v

This is from Sportscar International Magazine January 2004:

...the new M5 requires some careful thought. In an ideal world, a race car-stlye dry sump would have been used, but this system has its own drawbacks in a road car application, such as the added expense and packaging the the (their typo) external reservoir. BMW came up with what it terms a "quasi-dry-sump oil system." To cope with cornering forces beyond 0.6 g, the motor has two electric oil pumps, controlled by a lateral g-sensor, which pick up oil from the outer cylinder head and pump it to the main oil sump. The main oil sump has a continuously variable control to deliver the exact amount of lubrication required by the motor for the given conditions.

That should give you an idea of how a dry sump kinda works with out external reservoirs / packaging.

Guru_4_hire

a wet sump is what you are used too, a big oil pan on the bottom of the engine holding the oil with an oil pump and pickup immersed in the oil.

A dry dump is a completely different beast(I looked into one for my C3). it has an external oil pump, and the oil pan is just a big pickup on the bottom of the engine for the external oil pump. You can have multiple stages on the oil pump to pickup oil from all sides of the pan when you are cornering so oil doesnt buildup in the pan and cause drag on the rotating assembly. The oil then travels from the pump into a big tank in the 10" diameter, and about 16" long. the oil is squirted into the top and air bubbles from being whipped by the oil pump, is removed by running down a series of plates. the oil is then sucked by another stage of the oil pump through the bottom of the tank, and back into the engine. It also creates a certain amount of crankcase vacuum which helps your engine too.

The drawback is where do you put the great big 3 GALOON oil tank. and cost. complexity. etc.

427 C5

Great article and links!
Thanks for the info Coldsmoke.

davidfarmer

Drysump has advantages for dedicated track cars (increased oil capacity, better oiling in corners), but actually has more parts to break and increases your center of gravity in most cases. I see no advantage in a street car, and actually would prefer them NOT put it on the Z06

ivan111

Lowering that engine mass center of gravity is one big advantage of the dry sump lubrication that alone will improve the handling......

davidfarmer

this last statement is NOT correct

wachuko

The lower center of gravity comes from the ability to lower the engine more (similar to what they did with the Porsche Carrera GT). But you need to take into consideration the location of the external oil tank to determine the overall improvements. Porsche went with a smaller carbon fiber clutch that allowed lowering the engine even more.

It is my understanding that one of the major advantages of dry sump is to avoid oil starvation during high speed (G) cornering.

I will let those that have more knowledge in this are to chime in... ...but I for one would like the Z06 to come from the factory with dry sump...

Painrace

"OK", guys, from a retired race car driver, performance guys will love the dry sump system. In a race car the center of gravity can be lowered because the bottom of the oil pan is just a few thousands below the crank. This will improve cornering.

The oil is sucked out of the pan by two or thre oil chambers on the dry sump pump and put into an external tank. The oil pump sucks oil from the external oil tank and forces it through an oil cooler and into the engine to lubricate. You never have oil starvation. A Weaver dry sump pump will last almost for ever is you don't get any foreign parts into it. Race engines are know to blow up!

The dry sump sucks air as well as oil from the top of the engine which means no valve cover oil leaks. It also means you have to get rid of the air. We calculated the air moved through the engine was about 55 gallons per minute at race RPMs. We placed large hoses from the top of the oil tank back to the top of the valve covers and used the same air over and over. A breather was placed on top of the oil tank to allow fresh air in or too much air out.

There is a big improvement in throttle response with a dry sump motor and internal engine lubrication problems at high G forces are almost eliminated. I am counting on a dry sump system and a engine oil cooler. The engine oil cooler will be a problem in very cold temperatures. We could not get the oil temperature up with out completely taping the air off when ambient was at 45 degrees or below. I don't know how GM will handle this. Thick oil will smear the bearings in almost no time.

Just my two cents.

LTC Z06

Did you read the post above you? Your question has been answered, we don't need the extra cost and capacity, only a serious, dedicated race car needs a dry sump system.

Guru_4_hire

The only problem with the dry sump theory is the placement of the oil tank. they arent exactly small.

Bwright

It in fact is correct.

Bwright

The post above contained the following sentence:

"There is a big improvement in throttle response with a dry sump motor and internal engine lubrication problems at high G forces are almost eliminated. I am counting on a dry sump system and a engine oil cooler. " (My boldface). Why would you think a high-performance Z06 would not need technology considered a requirement for other such extreme road cars as the Carrera GT, Murcielago and Enzo? Don't say cost because the Z06 has always incorporated expensive technology (titanium exhaust, carbon fiber hood) at significantly lower cost than the competition.

With a declared mandate to noticeably increase cost and significantly increase the performance envelope it should be a given that the car will have a dry-sump oiling system. Whether or not they will do it remains to be seen but if they want to go to that next level they had better be seriously considering it because that is where the serious players are.

wachuko

I think I understand your line of thought... ...you do not want additional complexity or cost that will add to the price of the car...

Do know that 911 have had them since birth... It goes with the fact that the cars sold to the public were somewhat close to the cars raced. You could take your 911 to the track knowing it was built for it...(BTW, not the case today for the 996 and 997... only the GT3 are close to the cars Porsche sell for racing everything else is lower quality mass produced wet sump that they try to pass as a dry sump...)

It is clear that GM wants to keep its customer base but also wants to expand it and they have targeted 911 buyers. It will be a plus for potential customers of 911s the option of a Z06 with a dry sump... just one more feature that will appeal to those that do like to track their cars (even if it is not a dedicated track car).

Just as a car freak and even if I do not track the car, I like knowing that my car has technology used in race cars... will I be able to exploit the potential?, maybe not, but it is still a cool feeling...

Guru_4_hire

Can someone tell me where the 3 galoon tank would go?

rwd

If they're going to have two engines, then having a more expensive one with a dry sump is fine, but it's technological overkill for a street car. A wet sump 502 would do just as well for a lot less money.