I apologize for my ignorance in advance for asking these questions.
I think I understand the concept of dry sump in motor racing where it prevents the engine from going through oil starvation at high g's. What I do not understand is where does the oil actually reside. I usually see an external tank, which is supposed to replace the oil pan. If that is the case, the same g-forces in the corner will affect the external tank.
It's quite clear that without the oil pan, engine can be installed lower to improve the car handling. Why is this not used more on street cars? Cost?
Then I read the new M3 review in C&D during the weekend where they used two different oil pans, two different pump + hardware instead of just using dry sump to lower the engine. Why? It does not make sense.

 

Think of a dry sump oil tank like a fuel tank, fuel tanks don't starve the engine for fuel when they are subjected to high G loads. Dry sump tanks usually hold much more oil than a wet sump system. Porsches hold 12 quarts I believe. The oil tank has the benefitt of being able to be remotely located where the weight can be put to good use. The engine in a dry sump system can be set lower due to no oil pan and the oil is not subject to foaming like it would in a wet sump type system.

 

I have dry sump on my racecar.
Not only do you not get starvation in high G corners you also don't get the crank sloshing around in all the oil in the oil pan.
As Bieg says a dry sump usually holds more oil. Mine holds 14 quarts but part of that is the lines and coolers. The tank itself is 3 gallons but you only put it half full plus one quart. The oil needs to spin in the thank to take all the air out.
But all that said I have talked with other racers that have switched back to wet sump and just put some serious scrapers in the pan along with baffles.
When I ran a wet sump I also had an Accusump system hooked up so I wouldn't loose oil pressure in the corners.
Porsches aren't true drysump systems in that they still have oil where the crank is. They needed most of that oil for cooling.

 

The S2000 appears to have a complete baffle plate between the oil and the crank and a good pick-up. At 9000 rpm your oil would turn into whipped foam if the crank was in it. The only oiling issue on the car seems to be minor.. some high gee braking/turn conditions sometimes allow a bit of oil into PCV resulting in some smoke.

 

Thanks. Is there any disadvantage on having these on the streetcars? It should not cost that much more for an external tank.
It seems to me this is a better solution than what they have adapted in the new M3. Eliminating an extra oil pan and the second pump could have saved them some weight!!.

 

It's not just the tank you also need a pump and a couple miles of braided steel hose and fittings and remote oil filter and new oil pan. Just so you will get some ideas on prices.
tank $300
oil pan 300
pump 700
(from Pegasus)
The disadvantage of using a dry sump is the pump requires more HP to pull than a wet sump pump. If you are worried about loosing oil pressure in a turn use an Accusump. It costs about $150 then use a 'T' into an existing oil line.

 

There are many benefits to using a dry sump system, but most are needed for racing and are very tough to justify for street use.

No matter how good the baffling may be in a wet sump pan, the crank will still be whipping some oil.

A very well designed crank scraper will remove the oil hanging onto the crank without actually touching the crank. This frees up power.

The dry sump pump will actually create a vacuum in the pan while drawing the oil out. This is beneficial on race engines cause they have bigger clearances and would consume oil otherwise.

A dry sump tank usually also has baffles in it to help get the air out of the oil.

For something very commonly dry sump-ed like a small block Chevy, a complete dry sump system will run about $1500 and could be worth 10-15 hp, and that's on a 600+ hp race engine. At that price, everything would be a bolt-on. For the S2000, you'de have to fabricate the pan, mounting for the pump, and the belt drive. If you are paying someone to do it, that can easily run into the thousands of dollars.

Bottom line-save your money and put it into something you or the car really needs.