Normal and with in Porsche specs. Do not bother taking it to the dealer for this. Unfortuantly most Porshes burn oil. Both my Carrera S and Cayanne burn oil...the Carrera burns oil like a freakin' 2 stroke engine...around a quart every 800-1400 miles depending on driving style. It burns even more at the track. It's been to the dealer twice and seen a regional Porsche rep but Porsche could care less about this.

 

I recall my 993 air cooled drunk @ 1 liter per 1000kms and I was told by Porsche to expect that when i bought it.....understandable given the extra piston to bore clearances for air cooled etc.
The new breed of P engines with the high tech nikasil coated liners run tight clearances piston to bore. Reduces noise (and, supposedly oil consumption).....better for the environment and so on....
All engines must use oil as on each combustion stroke the liner lube is burnt off along with the fuel but this much..and, on an engine of this technology....doesnt add up to me .
Anyway, glad its not my engine doin that . Sounds like some of these new DFI 3.8's are borderlining on being 6 cylinder oil pumps .

 

Remember that this is a brand new engine after doing 1,500 miles.

My car has done 5,000 Kilometres and it's the DFI 3.6L. It too, gave me the engine oil indicator. So I pulled up at the P-car dealership I bought it from (I live near mine) at 5.30pm (workshop closed) and they gladly took it in, turned the workshop lights back on, and filled her up for me again. They didn't hesitate or asked me to come back the next day. All with a smile on their face and great service.

Oil consumption for a new engine is perfectly NORMAL and EXPECTED. Especially for an atmo engine with a high specific output. Just about every sports car I've owned (I've always bought new) drank a little oil in the first 5,000 kms. It should start to taper off at 10,000 kms but should continue to sip a little her entire life.

The good thing is that if the 997 tells u to top up your oil, it'll be only 500 mL. (half a litre). Don't know what that equates to in non SI units.

 

Agree that your 3.6 isnt an issue if it only used 500ml over its first 5000kms.
You say once oil light comes on it takes 500ml to refill.

Based on that, if the OP said he did 1500mls and oil light came on then thats way more than what you're using so...you're fine on that.
However that would mean that at 5000kms the OP would have required over 2 litres of oil.. correct? Sure, its still well under the one litre per 1000km standard of what is generaly considered acceptable... so thats fine, but, oil usage should really decrease after 5000kms tho.
The thing that stood out to me on this post is where there have been acouple of threads saying that there are some dfi's that use oil and some that dont. Owners with engines that do are indicating they are a little uncomfortable with that (as i think i would be too). Now If all DFI's used oil at a similar rate then i could safely say thats inherent with that engine. But thats not the case, so why is it so? So im thinking maybe the oil burners are associated to the early build cars and the late build are now resolved now. Just curious...

Hey i wonder if the DFI GT3 engines are using any oil and if so how much? And the new DFI Turbo engines? Probably too early to know yet but If anything the new turbos should use more than the others from having the higher combustion temps. It'd be interesting to know.

 

I like to think i was gentle with it. Only started pushing as i've now passed 3000kms. I hope that's enuf breakin.

 

Based on German P-car forum the 2009 DFI engines had an unusually high oil consumption. Starting from late 2009 models it seemed to become better.

Never forget that this engine is a completely new development, so maybe this oil issue is one of the bugs people need to tolerate when being the companies guinea pigs. With my VW Touareg I learned that I should never buy a car again which is not at least 2 years in production.

The main innovations on the 997.2 were the engine and the PDK. Always keep an eye on these before the warranty expires.

 

Agree. Similar story to the first lot of V8 cayenne turbos. I heard a few owners moaning about their oil consumption issues and the cost and volume of the oil required. Also heared a Porsche representative say that is normal for them to drink up to 1 litre per 1000ks and, offered these owners to come in for an oil fill whenever they liked. Sounds the same for these .2 dfi Carreras. Im sure Porsche is on top of this now .

 

It's not DFI engines which use oil... it's boxer engine which may use oil (DFI or not). Some boxer engines (DFI or not) use oil and others (DFI or not) do not use oil. This has ben stated here many times.

 

Yes..understand the boxer engine scenario and previous discussions etc, and yes its not as if any are using huge amounts...but still...why some DFi's do and some dont? Hmm..My understanding is there are "reasons for everything" and, with no concrete answers yet provided other than a blanket statement that boxers "do that" ...then they all should do that.
Not that it really matters.. but my money would be on...

 

Some DFIs do and some do not, the same way that some non-DFIs do and others do not. The point I am making is that oil use is not DFI-specific. Oil use has to do with varying engine parts tolerances.

 

Yes, sometimes it does. But with Porsche i imagine they'd have very stringent QA procedures where tolerances are concerned. I'd be more inclined to go with the scenario re variances that can occur in the combination of different branded OEM parts supplied for the build. Often an engine manufacturer must rely on two separate supply sources due to the inability of a given component manufacturer to be able to always provide continuity of supply at the time required.

 

I'd like to find a cheerful lighthearted way -- and especially a brief way -- to say this, but I'm not having a good morning healthwise, so I'll have to grind it out. Maybe we can put this to bed. (Though I wouldn't bet on it.)

There are such differences between suppliers, if only because of differing types of equipment used in the component production line. But you must remember the word you're discussing: tolerance. In our private lives we engineers may be as sloppy as others, but professionally, our words mean what they say. The application of such and such a part will tolerate those variations that concern you. The design has taken that into account.

I'm a design engineer, not a production engineer, but I'm aware of the techniques those in the latter category use. When sourcing the components not made in-house, the same care is taken as between two different production sources in-house or between a source in-house and one "from the out-house" as cynics say. Absent special political pressures, all sources have to meet the same criteria.

It certainly is true that other metrics, performance and otherwise, will show the effect of one part being on the extreme range of tolerance in one direction while another related part is on the opposite extreme. Where that relationship matters a lot, then we design engineers tighten the tolerances. Where it has less effect, we can keep the tolerances more loose, which means things are more manageable for the production engineers. If the relationship in one area is critical, we will have a co-tolerance. That is, "this dimension can be this high or this low a value, but the difference between this part and that one must be no more than such and such." That gets harder to manage on the production line, as you can imagine. Harder, yes, but I'll bet Porsche uses a lot of co-tolerances in their engine designs because their goal of high specific power output with light weight almost guarantees they must.

When the relationship is hypercritical, the co-tolerance will be so low that parts must be fitted in sets on the line. That's because you have tolerance build-up. That is, this part and the one next to it are on the high end of their tolerance range, but close enough together. Same with the next part added. But keep up that "both are a little bit on the high end" for a few more relationships and you have a combined set that won't fit through the factory door. Well, not that ludicrous, but you see my point. While designing, we have to assume that the deviation around the center spec matches some known statistical curve, usually Normal's curve. That's the one beloved of poor teachers, who "grade on the curve." We cut off the tails of that curve and allow for variation within the center section. The variations have to follow that curve, not all bunch up on one end for example. A statistical situation like that calls down the wrath of factory engineers on a source, whether in-house or contracted. When we cannot tolerate pairs of parts varying in opposite directions, we start including co-tolerances, and then things get really touchy, because each source may be compliant but ninety percent of their random pairings fail our standard. Not good. Expensively not good.

All that and more is one of the two dozen reasons spacecraft are so bloody expensive. On the production line, they hand-fit large groups of parts. Not hand install, but hand fit, as in measure this one and that one before you commit to using either one. Then add another by measuring it first. Designing so as to require sets that must be matched this way often compels the machinists to be involved with assembly. They fit as they build by "honing in" certain key parts. That is, they assemble the surrounding structure and make the last part ever so slightly oversize, a ten thousandth or even just a few hundred thousandths. Then they gradually work that part down with polish and other techniques until the fit with surrounding parts is as good as they can achieve.

Knowing the cost of all this, as well as putting numbers on "as good as they can do" is part of a design engineer's job. Sometimes we're designing to a performance standard, sometimes to a price target. Usually both, damn it.

So why this business with some of them use oil and some don't? Well, absent those political considerations I mentioned, the production standard is simply what you have already heard: one liter per 1,000 kilometers when translated to field use. Actually it would be expressed in hours of engine operation with a specified distribution of usage in rpm ranges.

You will not find that the result is so binary as we describe here. Unlike a failure mode, this is not a discrete phenomenon. Yes, some engines use more than others, but if you grabbed a truly random sample of perhaps a thousand engines, and put them through a pre-defined operation cycle for one hundred hours, you would find that every part of that curve was represented. That is, some engines would have the very low usage we brag of, and others would have the usage level near 1L/1kK that we ***** of, but all the usage rates in between would be represented as well. People provide the on/off switch, the binary assignment to "good 'un" or "oiler".

We each own only one example (well, typically, but saying that gives some of us a chance to brag), so being people and not engineers, we reduce our conclusion to "Oh, this one uses oil" or "Oh, got a good one. Doesn't use oil."

Some people will put their "oh it uses oil" threshhold at half the factory production standard or even less, but they will be offended or not by that conclusion according to their mood when they notice. ADias and I got ones that "don't use oil" by our standards, but we're both engineers and we know that oil is being used. We just don't see it on a digital bar graph display with pretty broad divisions. And anyway, I doubt that either of us would put a car in the "oil burner" class without it coming pretty close to that factory standard. Other aspects of the car are more important to us because our expectations are realistic.

Let me re-phrase that "some use oil and some don't" description. Depends on the car, but also your threshhold of annoyance.

I'll discuss those "special political considerations" if someone thinks they apply, but I don't have reason to think they do in this case.

Gary

 

One change that Porsche made when going to the new engine in the 997.2 was the use of Nikosil rather than Lokasil (spelling?). The former has silion distributed in the alloy and I believe the the cylinder surface is then etched. The latter uses a special coating applied to the surface of the cylinders to achieve the hard surface. I am not sure which is better but it was a change.

 

[quote=simsgw;2745558]
There are such differences between suppliers, if only because of differing types of equipment used in the component production line. But you must remember the word you're discussing: tolerance. In our private lives we engineers may be as sloppy as others, but professionally, our words mean what they say. The application of such and such a part will tolerate those variations that concern you. The design has taken that into account.

I'm a design engineer, not a production engineer, but I'm aware of the techniques those in the latter category use. When sourcing the components not made in-house, the same care is taken as between two different production sources in-house or between a source in-house and one "from the out-house" as cynics say. Absent special political pressures, all sources have to meet the same criteria.
.................................................. .................................................. .
Im not referring to tolerance per se. I was referring to differences in certain component design. So, what you are saying, as a design engineer, and i assume an engine componant designer engineer, that two separate designated OEM piston ring manufacturers are able to replicate one anothers "design" regardless of patents? Lets use oil control ring design and ring tension as an example. Are you saying that OEM ring manufacturers produce identical design in these two areas?
I ask as I'm yet to see two separate piston ring manufactures replicate identical ring sets for the same engine type. There is usually a difference of sorts. Agree specificationally they are manufactured to fit a given bore size, piston and piston ring groove dimension and produce an acceptable ring gap in the bore as per the engine designers specificational requirements but i'm yet to see two different piston ring manufacturers replicate identical rings in the two areas i specified. Have you?
The same applies to separate Liner and piston manufacturers. Specificationally they may be the same, so to satisfy the engine designers specificational requirements but again there are often differences found in RA, ovality, (liners), material hardness and metal compound etc. Your thoughts on this?

 

Well, my first thought is you're pretty knowledgable about this yourself, so I'll bet you know most of what I'm about to say, but for the sake of others, you and I can discuss the finer points.

Let me clarify my background first. I never designed a single automotive part. I'm afraid space was my field. Some spacecraft projects, a lot of launch facility design and when it became the 'in' thing, I was asked to start building the computer networks. That's where I finished my career. Mostly the space segment of such networks of course, given my early years. Air Force for twenty, then NASA and finally our own company.

On the other hand, I was a car enthusiast and learned to drive about the age of eight, so all the while my head was in space, my *** was in cars. I always related my training back to my hobby at each level, and among engineers, we tend to read each other's technical journals, trolling for ideas, mutual solutions to problems, or just being nosy. As part of a design exercise, a buddy and I spec'd out a car that used a computer-controlled engine and transmission. Our boss, CSUSAF, wanted to know where computers might be in 25 years, so he asked for examples. We didn't build it of course, and talk is cheap as they say, but our design for the interaction of computer and mechanical subsystems came out a lot like a modern Porsche engine and the PDK.

Unfortunately, that was in 1975, so I doubt it qualifies me as having designed anything automotive. With the right sort of training, a graduate engineer can get around a lot. Would you credit the bureaucratic snafus that led to my having a hard-rock mining engineer working for me at... wait for it... NASA? Not because we were building launch pads on that project either. Just... oh, never mind. You know Dilbert's pointy-haired boss? Well, his hand can be seen in some strange places. Think what that looks like on David's resume. "Wow! You built mines for NASA? Uh... where?" I'm sure he learned to say with a quiet smile: "Oh, that's classified. Sorry."

So we tend to know what our counterparts do in other fields, even if we would need a lot of cross-training to do each other's job. (And David did, but he was a bright lad.) With my lack of direct personal experience in the automobile industry understood, let's talk about your excellent points.

Quote:

Originally Posted by speed21

So, what you are saying, as a design engineer,[...]that two separate designated OEM piston ring manufacturers are able to replicate one anothers "design" regardless of patents? Lets use oil control ring design and ring tension as an example. Are you saying that OEM ring manufacturers produce identical design in these two areas?

Yes and no, as you know. What you're describing fits into one of two situations. No, three I think. (Anybody know why my text is coming out blue like Speed's? Oh well, never mind.)

In the first case, we have a problem as part of our design, and you got there before me with a great solution. After doing a build/buy analysis, we decide that buying the product you've already designed is better than designing and building our own. Unless we are seriously pressed by some outside factors, we won't declare you a sole source on a crucial part. That's puts us in an untenable relationship if your product is to become a vital part of our design. That sort of relationship is reserved for situations where our expertise lies in one area, like building sports cars, and yours lies another area, like audio systems. I don't know but what Porsche AG owns Bose, but let's suppose they don't. Then that is a good example. If I'm the chief engineer at Porsche, I'm perfectly happy to sole source Bose for the audio system because we don't really have the expertise in house to compete. And don't care to build that capability. When all is said and done, 'my' Porsche will be a Porsche no matter what's in the audio stack. If you become difficult to live with, if our relationship sours because Honda buys Bose, then we can always dump you and cut a deal with Harman Kardan or someone like that. But pistons? No. Not me anyway. It's a matter of judgment of course, but my judgment would be not to accept a sole source relationship on a part like that.

So what do I do? You have a great part already designed, you're not locked up with another manufacturer in a hostile relationship with us and I'd like to use your pistons. Or your rings, or whatever we pick for the example. We go to lunch, and probably dinner and a few breakfasts as well, while we negotiate. What I insist on for a final deal is that we get the right to use your design, including any patented features of course, with other suppliers. You have to provide full design information, background access for my engineers, and eventually a spec that means approved second source suppliers can build an identical piston or ring or whatever. Identical in all respects, within the limitations of the manufacturing art. Normally, this means you get a royalty on each one, but not necessarily. You might settle for "preferred supplier" status or something like that. Depends on my size, the volume of my potential orders and things like that. Basically, I'm willing to give you the profit your preexisting design has earned, but only if you're reasonable. If I'm as big as Porsche (or the USAF or NASA), I can always design my own. And don't think for a minute that patents keep us from doing that.

So in the end, even though you designed it with custom coatings, machining techniques, or whatever, each of our suppliers will be delivering it exactly the same. Because I won't give you the contract for this important part unless you agree to those terms. I know this, because we did that in the Air Force and I'm very sure Porsche engineers went to the same business schools as we did. We end up with multiple sources of this critical part, and they do have variations among them, but as few as we can achieve.

Would I do that with a crankshaft? Probably not. Despite my not being an automotive engineer, I feel comfortable surmising that the crankshaft is so intimately tied to the rest of my engine design that I'm not even willing to consider an outside supplier for the design. For the manufacturing, certainly. It's a high quality forging and machining job, but certainly nothing like as bad as many jobs in the space industry, and our contractors use multiple suppliers for critical components all the time. But they own the design. (Or rather 'I' do. Managing prime contractors is another whole issue we'll skip for now.) They don't source the design for something so unique to the requirement from somebody else, even with rights to use second sources.

Now, that's the first case and probably the one you were picturing. But maybe not. Let's go on.

The second case is we design the engine and ask for designs for the oil rings. Or we may do a first draft design taking into account its relation to other parts of our designs and ask for detail designs. We would naturally send that RFI to you as well as the other top manufacturers of aftermarket rings. (Or pistons etc.) But it is our design. We are seeking suppliers to build to our design. As part of the negotiation, we will probably offer the right to advertise yourself as a supplier to our design, 'my' Porsche in this example. But it still is our design. So yes, every supplier will be producing the same ring or piston or whatever to the limit of the ability of our production engineers to make that happen. As I say, equipment varies unless we make that part of the requirements, so sources vary, but they all are trying to make the same part, lest they get cut off.

Finally, we have after-market parts. Now this is a more benign relationship with prime manufacturers than marketing people would like to think. When we design somethin... well, not necessarily with spacecraft, but let me put on that hypothetical Porsche cap for now. When we design a car, we know the industry has to support us with consumables as well as a certain amount of aftermarket parts that really are thought of as permanent components. We decide what part of our market calls for that support and we make it feasible. The examples with Porsche are obviously performance oriented, but consider motorhomes for example. Ford and GM offer design data to let motorhome manufacturers use their heavy chassis without having to crawl all over measuring this and that, and taking wild guesses about structural strength, yield forces and other topics that will get them in court as well if a motorhome catches fire in Manhattan and burns an office tower, or something silly like that. Different parts of the business work together, because a prime manufacturer cannot expect to satisfy all parts of the market.

Aftermarket replacements for pistons, rings, and what have you, may indeed give different results than our factory design. That may be true even if you sell that piston design to us and then sell pistons in the aftermarket. We may well allow you to do that, with restrictions on the second suppliers that they may not re-use your design that way. All part of the negotiation. But as the original designers, and with your inside knowledge of our car you gained while working with us, you may decide that nikasil is a good deal for your customers and change to that alloy, while we still want to stick with the older technique in the production line. That's okay. The customer better expect different results from an aftermarket product, or why is he voiding his warranty and going to the trouble to change?

Bottom line? My thought is you knew most of this already, as I said at the beginning, but it doesn't hurt to explain it to others. Aftermarket suppliers often have some of the best engineers in the business. If I am that Chief Engineer at Porsche, I'm not going to agree that they are better than my in-house engineers. Not on your life. But I may find it economically or schedule-wise more effective to use their design talent to solve my in-house problems. But when I do that, on a part or subsystem I consider is part of the essence of my own product, then I"m going to get the right to treat their design work the same way I do our own work. So the question doesn't affect that discussion before.

As for aftermarket parts for some of our customers... Well, the aftermarket suppliers can very likely provide designs that are better for a small segment of our customers than our own answers intended to satisfy the whole customer base. Wheels are an excellent example, and with some complex reservations, so are those pistons you mention. Just don't expect to come running back to me for warranty work... uh, I mean back to Porsche if you go changing something so interrelated to the rest of the design as is a piston.

Incidentally, with all that said as an engineer, let me add something as a new owner. Porsche is the most adaptive large sports car manufacturer in my experience. It is usual for only the very low volume manufacturers to let you get so many different parts of the car tailored to your own expectations, but large manufacturers usually limit that sort of thing to a special subdivision, like a racing relations group. I am amazed at how many things I could custom tailor from Porsche if I had the urge. I don't know that they offer carbon-fiber wheels like HRE, but I wouldn't be surprised to learn they did. On special order only of course.

Gary