chuck911

Oh I have my doubts about your question being genuine. If it were then you would find no reason to specify "991 engine rings". That's the kind of thing you do when you want to be able to come back later with, 'Aha! See! Nobody's tested and torn down a million 991 motors so its all BS.' If I supply study data for the 991 you'll say it doesn't apply to the 991S. If I supply data on the S you'll say oh well mine was produced after that it doesn't apply. On and on. If you were genuine curious you'd understand we're talking about something that is either true of all internal combustion engines, or none.

Ditto the part about "and nothing less." I forget what we call the logical fallacy above, but this one's called the straw man. In the straw man the questioner sets up a claim that has not been made, refutes it, then claims that this refutes the original claim, even though they are different. The claim that "rings only seat properly at full power and nothing less" has not been made. The claim has been made that shifting at 4000 is too far down on the power band, and that full throttle is called for, but the absolute "and nothing less" is uncalled for.

Of course I guess its always possible the obvious traps you've set are inadvertent. Maybe you really do understand that we're talking about engines in general and not any one specific engine. (If you disagree then I must point out that the burden of proof is on you to show why we are obliged to consider any one particular example unique.) But then it seems to me that if you genuinely did want to understand the situation you would simply read through the thread above, read some great stuff like this http://www.avweb.com/news/maint/1828...l?redirected=1 and figure it out for yourself. Don't let Porsche be your authority figure. Don't let me be either. Be your own.

bccars

Deleted!

chuck911

No, you wrote a "very specific" question you knew the answer to in order to make a rhetorical point. Or do you really expect people to believe you honestly thought there might be scientific studies where a whole bunch of brand new model 991 engines were run on different load protocols, then torn down and examined just to test this one hypothesis? Really?

Here's one we might all be interested in:

Is there any study or database of any kind done by Porsche or any other manufacturer on any model engine now or ever built that supports the need for a 2,000 mile long and low 4,000 RPM limit break-in?

bccars

God no, you beat me to it apparently, too late with my delete. :-)
Anyhow, for me it ends here.

MerlinsGarage

Porsche, as do all manufactures, have break-in procedures. If there wasn't one written down the process would go rogue and OEM's certainly don't want that.
So, IMHO, the "Procedure" is a gentle reminder to those without the good sense to refrain from beating the bloody hell out of the car on the way home from the dealership......and every day after that.
For the rest of us common sense prevails and parallels recommended guidelines. An occasional departure from said "Procedure" will never cause a problem. Of course this is all IMHO.

Best, Bret.

Rainier_991

Our cylinders are Nicasil treated types - are they not ? There is no iron or steel sleeve with a rough honing pattern and the desired sharp edges.
This would imply that the method of high combustion pressure to seat in the rings is not going to do much. There is no honing to speak of...

We use very similar engines in aviation fitted to small aircraft, also Nicasil boxers. They are produced to such right tolerances there is not much in the way of running in required (which is impractical in an aircraft anyway). This means, pretty much from the go it is full power for take-off...

of course, we don't worry about gear boxes, diffs and other drive train components which may need a bit of bedding in.

Rainier

MerlinsGarage

Rainier,
I remember using mineral oil for the first 5 hours of break in on the C-152's, then on to synthetic. Don't see that anymore in todays engines.

chuck911

http://www.aera.org/engine-professio...l®-and-alusil/

"Let’s begin by covering what Nikasil® is. Nikasil® or NiCom® (1967 Mahle trademark) is electrodeposited oleophilic nickel silicium carbide coating. Simply put, it is a nickel plated silica carbide coating often applied to aluminum cylinder bore IDs but can be used for many applications where tight tolerances and superior wear surfaces are indicated. The oleophilic feature of Nikasil® gives it a natural tendency to absorb oil, which in turn helps the oil retention of the coating."

"Let’s start with Nikasil®. Nickel silicon carbide composites are applied as a thin coating of about .002”-.006” thick. We are told that anything thicker than .006” and the coating may lose some of its elasticity and become brittle. So, depending on how much thickness you have to work with, careful honing is a viable process to restore a factory surface finish."

"Mahle recommends honing no more than .001” from Nikasil® coated bores and only to restore cylindricity to any wear areas. If wear is greater than .001”, it is advisable to have the coating stripped (in many cases this is a simple electro chemical process and does not require boring) and fresh nickel silicon carbide applied. Check with the supplier of coating material for correct honing stones for this process."

MarcusG

For what it's worth...

http://www.rennteam.com/forum/page1....bhy9wniyv?vs=0

This new Turbo S owner and I'm assuming he's in Germany by his delivery date and sig.

Check out the end of his second post about 3/4 down the page.

"If you have any particular question or if you want me to check out something specific, just do it. Keep in mind that I'm still breaking the car in, even if the German manual doesn't describe a specific break-in period anymore. No launch control, prolonged Vmax driving and track driving for the first 3000 km though. Just to be safe."


German manual doesn't mention a specific break in period?

Not trying to fuel the thread anymore than it is. Just reading from others.

alexneo

The european manuals don't mention any break-in process, again I have asked the service in regards to the procedure. It is not required, I believe people are taking it too seriously. Really...

bccars

Again, I live in a country next to Germany, so clearly that's in Europe. And my manual does have the instructions !

Suzy991

I've read loads of BS on this thread and didn't want to interfere and just laugh, but couldn't resist anymore
Here's the instruction from the German/Swiss/Austrian manual for the 991Turbo S. Translating you'll have to do yourself, Google is your best friend (Sorry, I'm too lazy today)



Hinweise für die Einfahrzeit

Für Ihren neuen Porsche sind nachstehende Tipps beachtenswert, um die optimalen Laufeigenschaften zu erreichen.

Trotz modernster Fertigungsmethoden mit hoher Präzision lässt es sich nicht vollständig vermeiden, dass sich alle beweglichen Teile "aufeinander einlaufen" müssen. Dies erfolgt im Wesentlichen während der ersten 3000 km.

Information

Sie sollten während der ersten 3000 km:

Längere Fahrstrecken bevorzugen.
Häufige Kaltstarts mit Kurzstreckenbetrieb möglichst vermeiden.
Nicht an Clubsport-Veranstaltungen, Sportfahrschulen usw. teilnehmen.
Hohe Drehzahlen, insbesondere bei kaltem Motor, vermeiden.

Öl- und Kraftstoffverbrauch

Öl- und Kraftstoffverbrauch können während der Einfahrzeit etwas über dem normalen Wert liegen.

Die Werte für den Öl- und Kraftstoffverbrauch finden Sie in den Technischen Daten:

Beachten Sie bitte das Kapitel "MOTORDATEN"
Beachten Sie bitte das Kapitel "KRAFTSTOFFVERBRAUCH UND ABGAS".

Einbremsen neuer Bremsbeläge

Neue Bremsbeläge und Bremsscheiben müssen sich "einschleifen" und haben deshalb erst nach einigen hundert Kilometern ihre optimale Bremswirkung.
Die etwas verminderte Bremswirkung muss durch stärkeren Druck auf das Bremspedal ausgeglichen werden. Das gilt auch nach einem Bremsbelag- bzw. Bremsscheiben-Wechsel.

Einfahren neuer Reifen

Beachten Sie, dass neue Reifen während der ersten Zeit noch nicht ihre volle Haftfähigkeit besitzen.
Die neuen Reifen sollten daher während der ersten 100 bis 200 km nur mit mäßiger Geschwindigkeit gefahren werden.




Suzy (via iOS app)

Rainier_991

No specific break in instructions limiting RPM here either.
Essentially just somewhat vague instructions to take it easy for a while - similar to the German instructions.

Anyway, with super-human self control I did nevertheless managed to avoid launch control until 3000Km. It happened at 3000.1Km. Just had to.

Rainier

Rainier_991

Exactly my point. No honing to speak of. Nothing more than the slightest roughing quite similar to burnishing. That's exactly what we do with our aircraft engine cylinders (the Nicasil ones). It's to make the oil adhere.

Way I see it, any sharp edges left protruding into the chamber are so microscopically small and thus weak they will be gone by the time the ring has scraped a few hundred times over them - guessing of course.

BTW, just as an asside, my Porsche shop qouted me a price of around $16000 for a 3.8 liter engine as fitted to the C2S. The aircraft engine I am specifically refering to has less than 1 liter capacity, 4 cylinders (boxer, water and air cooled), generates 100hp and is around $30000. So, Porsche is cheap...

Rainier

Rainier_991

Yeah, the engines used in the 152's are pretty much the same still as my Grandfather would have used. Cost of certification prevents any meaningful modernisation of the fleet. The Bureaucrats won this battle long ago. Sadly.

Rainier