RedBarron2007

I like to think I have forgotten more about the internal cumbustion engine than most people ever truly know and you guys have so many stories about this engine or that engine, even i am confused.

is th 3.8 in the s cars from 2006 up a wet sump, or "both wet and dry" (that **** is retarded and makes no sence) or is the 009 and up cars based on a totally diff design?

Harvey Yancey

The 997 Carrera's engine is the M96/05 and is basically the same as the 996 range but with some modifications.

The 997 Carrera S's engine is the M97/01. According what I have read 70% of its parts are NOT interchangeable with the 3.6 M96/05 engine.

The 997.2 engine is a brand new design.

simsgw

Long weekend, too tired to get into details but briefly, this is what the terms mean. The sump (hopefully obviously) is where we collect the operating oil for a machine. We use various methods to apply oil, usually under pressure, to the parts that need it. Then we let gravity and the machine operations combine to gather the surplus back to the sump.

In general, for engines, a wet sump means the oil is left there in a puddle and we pump it to the points that need oil to start the cycle again. A dry sump means we remove the oil from the sump to another container and pump it from there. The engineering significance is the dynamic effect. Aircraft engines in particular must operate at all angles relative to gravity and inverted as well for some. Clearly our puddle of oil would be all over the place when we tried to pick it up and send it to the points that need it. The pick-up pump[s] would suck air and that would interrupt the flow of lubricant, which is sometimes tolerable, or even pressurized operating oil, which generally is intolerable.

With a 'dry' sump, we have scavenger pumps that don't mind sucking the odd bit of air. As the oil gathers in the sump[s], the scavenger pumps move the oil to a reservoir protected against dynamic effects. Pressure pumps have pick-ups in that reservoir that never run dry (assuming the oil is kept filled properly) so they never interrupt pressure to the lubrication points and oil-operated parts of the machine.

Sometime around WWI, we began using scavenged dry sumps and a central reservoir for aircraft engines. When sports cars began pulling side loads high enough to make the issue important, their designers began using it as well.

I speak subject to correction, having read the description only briefly a couple of years ago, but I believe this is the point that confuses the discussion: Previous models of Porsche used a dry sump and a separate reservoir, just as I described above for aircraft. Sometime later, by the time of the 997.2 at latest, they moved to a separate reservoir in the technical sense, but they cast that oil containing system into the engine block.

Clearly, the engine dynamics do not care explicitly whether the oil pick-up reservoir is bolted to the side of the engine compartment or molded into the engine block. An engineer with an objective viewpoint would only care enough to ask about side effects of the choices. (Viz: does the integral-casting method impose vibration effects that froth the oil? Or, does the separate system introduce reliability issues because of the necessary piping from the pick-up point to the lubrication and operation points within the engine itself? Questions like that. Clearly, Zuffenhausen asked those questions and liked the answers attached to the integral-casting method.) But mechanics seem to be bothered by the concept. They want to point to a separate tank of oil somewhere near the engine to confirm it's a dry sump in operation.

That's nice for a rule of thumb but not worth obsessing over. The essential point is whether two types of pump are in operation. In a wet sump engine a single type of pump[s] picks up the oil from the sump[s] and delivers it to places where needed. A dry sump engine uses scavenger pumps to collect the oil from the sump and move it to the point where the pick-ups for pressure pumps are waiting. The first type don't care when they run dry while you're cornering hard. They self-prime and resume gathering oil when the plane (or car) returns the gravity vector to an angle that gives them oil to pump. The second type care a lot. They need that oil supply constantly available. (Computer types will recognize the reservoir as a buffer of the type we use in logic to ensure the downstream operations never "run dry" of operands.)

Applying that acid test, we learn that the current engines are of the "dry sump" type because they have both types of pump. Several scavenger pumps move the oil to an integrated reservoir. Integrated with the engine structure, but separate from the sump. I've forgotten exact locations but I'm sure someone knows. If not, I can look it up. High pressure pumps pick up the oil from the reservoir and shove it everywhere, including a couple of systems that must have such pressure continuously to operate. But the existence of the 'buffer' reservoir means the engines are dry sump in operation. The whole wet-dry sump business is a semantic escape for people looking to that old rule of thumb about the can riveted to the side of the engine bay.

Gary

DHC

Gary - insightful as always. It would be nice if someone could amalgamate all of your posts, for some excellent reading!

To the original poster, your premise is absurd. One in eight? When pigs fly.

91469972

Ok F4GIB nice post about something that is complete BS. It would be better prior to a post making sure that the info posted is not something passed on through numerous people by word of mouth.

ADias

To complement Gary's post re 997.2 integrated dry sump:

hpowders

997.1 coupe. 4 1/2 years young. Engine purring like new. Never a problem.

simsgw

Isn't that beauty in motion? Can't you just picture the effect on the oil puddle in a "wet sump" engine?

Gary

russm535il

How about the new 991 I know that engine is a totally new design
Any issues surfacing or has Porsche built a bulletproof unit ?
Russ DeJulio
2006 Carrera

myw

the 991 engines should fine other then a starting/stopping problem that is pretty well documented on the forums (which i believe is a software issue based on the forums).

with that said the base/S 991 engines i believe are based on the 997.2 engines, so the reliability should be very similar to that of the 997.2

yemenmocha

The "Porsche Professional" could have used a basic statistics course, perhaps? or knows that he is exaggerating and is a royal douche...

stronbl

Agree with the above comment. Both (991 & 997.2) are 9A1 design and as such are complementary to one another. The 991 version has some mods in the oil pan fins and a few other minor changes but pretty much the same. In the newest 9A1 in 991 GT3 the dry sump is even more evolved and one could even say it is a ver 2. Overall reliability of the 9A1 has been very good (minimal catastrophic failures) but the evolution to GT3 et al will be a real test. Check back in a few years for news. By the way I had forgotten just how cool the video posted by Tony was in post #51. Fun to watch it again.

RPL

So the M97 doesn't have the wet and dry sump? Just the wet sump?

KNS

It's really just a wet sump. Porsche states "integrated dry sump" in their literature but that's just marketing BS.

mikeborden

Yes, but it does have scavengers in the engine. So, not totally just wet sump.

yeah, marketing gimmick, but it works.

Mike