whats in a dry sump?
Discussion
Oil is held in a seperate tank. Allows engine to be placed lower in the chassis because the traditional sump doesn't exist. Also, for high g-force curves, dry sump feeds oil consistently to engine parts. Wet sump can allow oil to accumulate unevenly due to g-forces. This isn't really important on a road car in most situations but more so for track and racing.
Just to expand on silver993tt's response, the dry sump is constantly sucked dry of oil by a scavenger pump that then pops it into the separate oil tank. The HP oil pump then takes the oil from the tank and feeds the engine.
Conversely, on a wet sump engine the HP oil pump is sucking straight from the reservoir of oil in the sump. Even with clever arrangements of baffle plates, etc., a long sweeping bend taken at speed can lead the the HP pump sucking air and starving the bearings - bad news!
Conversely, on a wet sump engine the HP oil pump is sucking straight from the reservoir of oil in the sump. Even with clever arrangements of baffle plates, etc., a long sweeping bend taken at speed can lead the the HP pump sucking air and starving the bearings - bad news!
Not always as dry as one might imagine, you should still always use the big oil tray! (when changing the oil)
A dry sump is not just to prevent oil starvation, it also enables cars that are air /oil cooled to stay cooler because of the larger capacity. We think of our cars as air cooled but we all watch the oil temp guage when giving them their exercise.
A dry sump is not just to prevent oil starvation, it also enables cars that are air /oil cooled to stay cooler because of the larger capacity. We think of our cars as air cooled but we all watch the oil temp guage when giving them their exercise.
jeff m said:
Not always as dry as one might imagine, you should still always use the big oil tray! (when changing the oil)
A dry sump is not just to prevent oil starvation, it also enables cars that are air /oil cooled to stay cooler because of the larger capacity. We think of our cars as air cooled but we all watch the oil temp guage when giving them their exercise.
But are we not 'air cooled' in that the air cools the oil which lubricates/cools the engine? In water cooled what does the water cool - oil or engine or both?
roygarth said:
But are we not 'air cooled' in that the air cools the oil which lubricates/cools the engine? In water cooled what does the water cool - oil or engine or both?
I didn't want to get into of what does what, I was just trying to help the original poster.
Oil temp is very important in a P car and it does go through an oil cooler which likes to have plenty of air round it.
roygarth said:In the 928 the air cools the water, then the water cools the oil (for engine and gearbox)...which is why 928 rads are so expensive!
But are we not 'air cooled' in that the air cools the oil which lubricates/cools the engine? In water cooled what does the water cool - oil or engine or both?
jeff m said:
But are we not 'air cooled' in that the air cools the oil which lubricates/cools the engine? In water cooled what does the water cool - oil or engine or both?
I didn't want to get into of what does what, I was just trying to help the original poster.
Oil temp is very important in a P car and it does go through an oil cooler which likes to have plenty of air round it.
My question was not meant to appear...what's the word...wanky!? But the original post got me thinking and I realised I didn't know the answer. Rennlist describe 911/964/933 etc as 'air/oil cooled' and 924/928 etc as 'water cooled'. I was trying to work out the technical difference...still not sure I've got it!
In a conventional water-cooled car the engine is coooled by circulation of water through pipework/ducts built into the engine and the water is cooled by passing it through a radiator.
The original 911s were air/oil cooled in that they had no water cooling system at all. Later variants (to 993) have water-cooled heads and air/oil-cooled blocks. 996 have traditional water-cooled engines.
Hope this helps.
The original 911s were air/oil cooled in that they had no water cooling system at all. Later variants (to 993) have water-cooled heads and air/oil-cooled blocks. 996 have traditional water-cooled engines.
Hope this helps.
kevinday said:
Later variants (to 993) have water-cooled heads and air/oil-cooled blocks. 996 have traditional water-cooled engines.
Sorry Kevinday - what is this about water-cooled heads in 993s? That's news to me.
As far as I was aware all 911 up to the 996 are described as air-cooled but are essentially oil cooled in function, which is why we have 11 litres of oil in the motor.
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