Wet Sump Question

[bryanearll]

Ok, over the last couple of days I have educated myself on the difference between a wet sump and a dry sump.

My 2001 996 C2 has a wet sump. I did read on the rennlist that an option was available to improve the wetsump (and thus better protect the engine). What's that bad boy cost installed? Anyone know, anyone updated their 996 in this fashion?

Secondly, it would seem to me that AX would not be the kind of sporting event where sustained G forces are likely to be found. Of course, what do I know? But it is my understanding that it is the sustained G forces pushing the oil through the baffles and up against the wall and away from the sump that cause the problem.

I guess the real question is: Is driving in the AX better than driving in a DE or TT at Button Willow when looking at the Wet Sump issue OR MAY I ASSUME (help me here), THAT AS LONG AS I HAVE STREET TIRES ON THE CAR I'M GOING TO SLIDE LONG BEFORE THERE IS A "G-FORCE" PROBLEM? After all, I have stock springs and suspension and soon 220 Kumho's; it's not like I'm going to pulling 1.6 G's.

Bryan

[MikeD]

I looked into this briefly a while ago since I have the same issue and have seen a couple cars end up in the shop for apparent oil starvation. I've heard of a kit that can be added to help with the problem, but as I understand it, will not "solve" it completely and is something like $1,500 NOT installed. The best advice I have heard so far is to keep the oil topped off after every run session.

You're right, for AX it is not as critical. But when you get to the big tracks like Willow Spings, California Speedway, Buttonwillow you should keep a constant eye on the oil level.

[bryanearll]

I've been equally concerned about overfilling the oil reserve. My car doesn't burn ANY oil, and after 3000 miles (since I've owned it), the oil level is still "full" or "down 1 step" depending on how long it's been sitting. That's not even 1/2 a quart.

Keeping a constant eye on the oil amount can only be done while stopped. The oil pressure ALWAYS looks too high to me (between 3.5 to 4.8 ) unless I'm driving to San Diego crusing in 6th.

I read another report about changing the oil after every AX but that seems a bit excessive.

I believe , that I can get a better time by driving the car instead of pushing the car as hard as I did in December but we can see what the clock says.

(I presume for the 944 Spec cars this isn't an issue as they have a dry sump, right?)
b

[MikeD]

I've been equally concerned about overfilling the oil reserve. My car doesn't burn ANY oil, and after 3000 miles (since I've owned it), the oil level is still "full" or "down 1 step" depending on how long it's been sitting. That's not even 1/2 a quart.

No, you are right. You do NOT want to overfill as that could lead to RMS problems . But even a 1/4 quart low can lead to oil starvation issues (or so the story goes). They say that this engine will go through 1/4 of a quart for every 8 hours of track driving. However, I've noticed about half that so far. We'll see as the engine gets older though.

I read another report about changing the oil after every AX but that seems a bit excessive.

I believe , that I can get a better time by driving the car instead of pushing the car as hard as I did in December but we can see what the clock says.

(I presume for the 944 Spec cars this isn't an issue as they have a dry sump, right?)

I understand the 944 guys do have this issue (they have a wet sump also). But they can add an Accusump (or something like that) that helps. I'm sure Tim or the other 944 guys can add more meat to that thought though.

[ttweed]

I've heard of a kit that can be added to help with the problem, but as I understand it, will not "solve" it completely and is something like $1,500 NOT installed.

I have seen this kit advertised for $1300, but I believe installing it VOIDS YOUR WARRANTY!

I think you are OK on street tires, Bryan, the problems seem to be only when you have race tires on the car and pull sustained high Gs.

TT

[Bob Gagnon]

The 996 has scavenge pumps in the camshaft housings to move oil from them to the sump. This is required since there is no natural drainage gradient since the exhaust cams are essentially at the level of oil in the sump.

This use of scavenge pumps is the reason Porsche calls it an "integrated dry sump". So part of the engine is sort of dry sump, but it is really a wet sump.

The pumps are driven by the exhaust cams and since the cylinder heads are identical side to side, the pump is in the front in a 911 on the drivers side and in the rear on the passenger side. This is reversed on the Boxster due to the reversal of engine placement.

The upshot is that during long periods of braking and turning to the left under high G conditions with racing tires oil accumulates in the forward right hand cam box.

The "Motorsport Oiling Kit" for the 996 installs a second pump on the right side behind the original pump. The second pump has a line going to the forward section of the right camshaft housing to suck out the oil under the conditions that cause the problem.

I think it is a rare situation to have a problem.