Can one convert from wet to dry sump?
 

With Porsche going to wet sumps lately, I've been wondering about this question. If I understand correctly, a dry sump mainly involves having an extenal oil tank from which the motor is lubed - instead of using the bottom of the engine block as the oil tank. So how hard would it be to convert a wet sump car to dry sump?

Janus, I was talking to an Porsche service advisor at the track the other day about this very subject. He said Porsche offers a kit that lets you add 3-4 extra quarts of oil to a Boxter. When he tried to order the kit, they told him it was only sold in Europe. He said he thought there was an after market kit, but I didn't get the name because my run group was up.

Panorama had ( of all things) a tech article many years ago how a 356/912 engine was converted from wet to dry sump....

It might be more difficult for a later Porsche ( 996 type) since the "wet-sump" is a sorta "semi-wet" or "semi-dry" sump....

... I guess I would like to first see/understand a cross-sectional view of the current system..to find out what this "really" means.....

- Wil

It is done all the time in cars and motorcycle car conversions. I'm not suggesting its "easy" or "inexpensive" sadly. I'd say that in a car like a corvette where this is often done to go full race it would still run $4-5k to do so. Converting a bike engine in a Lotus 7 is much cheaper due to size so it all varies.

If there is a kit that is one thing otherwise I think you'll have to be quite creative for space back there. You will also need to be very good at fabricating or have deep pockets. Of course if you have deep pockets, then you might just be better installing a GT3 engine.

Can I ask why you would want to convert?

You know, they call the air cooled 911 a dry sump but there is a lot of oil in the belly of our engines. the bulk of the oil is simply not stored there.

Per Krogger's comment, there is probably little need to convert unless you are going endurance racing.

Don

The air cooled 911 is most definately the classical definition of a dry sump .... let's not confuse the issue !!

Wil

Because if you put R-compund tires on a stock 996/997 or Boxster, you will starve the engine of oil under anything over 1.4 lateral G's, and also can end up with excessive oil in the cylinders.

So in other words, if you're serious about tracking the car, it must be done.

The GT2/GT3/996TT all use the 964/993 bottom end with dry sump, so they are not affected by the inadequacies of the "integrated sump" system on the regular production cars.

Is it possible to change the crankcase to 964/993? Is the crankshaft and rods the same?

Re: Can one convert from wet to dry sump?
 

http://www.accusump.com/

Tom

Let me get this straight.

You want to dump the external oil tank and convert from a dry sump to a fully wet sump system. This means the entire oil capacity is contained within the crankcase. That's ~10 quarts, btw. That right so far? In order for 10 quarts to fit, OK, let's just make it 4 quarts like most cars, the crankcase sump must increase in volume to contain the oil. Either that or leave it as is. Merely pouring more into the crankcase will bring the oil level closer to the crank, perhaps partially submerging it and the other reciprocating parts in oil and create all kinds of bubbly in the lube system. Or one can modify the crankcase sump by widening it and/or making it deeper (ka-ching). I hope you didn't lower the rear end because you may now have less road clearance (a plus is that you can now install larger tires in the rear after raising it). Reduce oil capacity and the oil cooling system has to be more efficient.

One of the main advantages of a dry sump system is to reduce windage losses, HP loss created by the aforementioned crank whipping through the oil. In that Porsches are still susceptible to G forces allowing air into the oil pump is a design flaw in their dry sump system. If oil centrifuges away from the oil intake, then one must devise methods to reduce or prevent this via baffles on the crankcase walls and/or around the oil pickup and similar windage trays and baffles in the oil tank. For example, the existing filter screen between the crank and the sump area can be replaced by something more substantial to reduce oil from climbing up the crankcase walls, yet provide large-enough drain-back openings.

To increase the oil capacity in the crankcase, how about replacing the existing internal pressure/scavenge pump with an external belt-driven dry sump pump (and necessary fabrication)? That would reduce windage effects (and oil) inside the crankcase (pretty costly fix though). However, you'd still have to prevent oil from centrifuging inside the tank.

Accusumps and similar oil pressure accumulators are designed to precharge the lube system before starting and sometimes after shutdown (turbo cooling); not meant to be the primary source of oil pressure during engine operation.

MHO,
Sherwood

911pcars sez ...." Let me get this straight. You want to dump the external oil tank and convert from a dry sump to a fully wet sump system...."

Ahh...no...look at the poster's title.." Can one convert from wet to dry sump? ..."

Seems you got this totally backwards...... ??

- Wil

Totally a$$ backwards. Duh. I should stay off the meds.

Thanks Wil
Sherwood

If you're not going to use your meds, mind sending them to me? :D
-Chris

It comes with age.. I should know, there are three things that go bad with age....the first is memory...and I forget the other two ....

- Wil ;)