I'm a life long mechanical engineer too. The answer is that your manual is not written by mechanical engineers. It is written by lawyers. Just look at all the notes, cautions and warnings. All based on law suites from the US. (Thanks Paul Walker) Don't breath the exhaust fumes because you might die. Don't leave your ipod in the car in the summer because it might fail. (these are real warnings)

As LexVan mentioned, some of us (people from all around the world) did take pictures of our manuals and posted them in a different forum and all break-in procedures were different. The US was the most restrictive. What changes when crossing a border? Not Physics but the litigious nature of our societies. Guess which manual was most restrictive?

At 400 miles on the odometer, I was getting my 981 sideways on the Stelvio pass at 7k rpm and 246 degree oil temp......and now at 36k miles. Oil gauge hasn't budged. Same with my 991.2 but it only has 2800 miles on it.

....and since we are on the topic.....the manual is better than the pdk, SC and PSE are a must and the base engine is more than adequate for the street. LMAO

 

Yes. To which I'll add one more: 5. Don't lug the engine.

 

Quote from the manual of a 991.2:

"The moving parts of a new vehicle must be run in. The parts require the first 2000 miles (3,000 km) for this purpose. The oil and fuel consumption may be somewhat higher than normal during this period.

During the running-in period, drive as follows:

Preferably take long trips. Avoid frequent cold starts with short-distance driving whenever possible.
Avoid full throttle starts and abrupt stops.
Do not participate in motorsport events, sports driving training or similar events.
Avoid high engine speeds of 4,000 rpm or more. Drive at low engine speeds when the engine is cold.
Do not let the engine labor, especially when driving uphill. Shift to the next lower gear in time (use the most favorable rpm range).
Never lug the engine in high gear at low speeds. This rule applies at all times, not just during the break-in period. .
There may be a slight stiffness in the steering,gear-shifting or other controls during the break-in period which will gradually disappear."

 

Break in procedure (for driver):

1. Complete 5 minutes of jaw stretching and grimacing.
2. Start car and begin driving.
3. Ease into sh*t-eating grin.
4. Take frequent breaks to allow facial muscles to relax.

 

If you don't plan on keeping the car beyond 4 years or 50k miles, then drive the damn thing like it was stolen from minute 1 of day 1.

 

...

 

Have only looked at dealerships so far. Thinking that a CPO'd car plus a PPI is probably enough to not worry about it. These engines are pretty tough.

 

Break-in on a modern engine is really all about seating the rings. And I suspect on a 991 that the rings are seated on the engine dyno at the factory, which is why the driving instructions for "break-in" are so vague (rings want high cylinder pressures pushing them into the cylinder walls, and you generate high cylinder pressures by short WOT runs and engine braking). There's no way Porsche is relying on end users to properly seat the rings.

The bearings run on a film of pressurized oil and thus don't need to be broken in. On the old 911's with mechanical rockers you had to run in the cam lobes and rocker pads. But that ended with the 993.

tl;dr drive a 991 easy for a few hundred miles and then go to town. I've never heard of a 9A1 engine with an oil consumption problem, i.e. everyone's got properly seated rings.

 

So, when you have two new turbochargers fitted to your car - why does Porsche specifically tell you to not exceed 5000 rpm for 500kms and why does it say this in the fitment instructions provided by Porsche Germany, to the installation mechanic.

The exact words are as follows

Engine run-in:
Engine speeds greater than 5,000 rpm are not permitted over a distance of 500 km (310 miles). The maximum engine power of 331 kW (450 hp) depends on the total mileage of the engine at the time of the retrofit and is achieved at a total mileage of approx. 10,000 km (6,250 miles) or higher.

From:
Power Kit (I-no. X51)
Installation and Modification Instructions 1
Jul, 2017
911 (991) 8/17 EN 1001

So its clear Porsche recommends a run in period Irrespective of what some random "SA" may say or whether an individual believes the manual was written by "lawyers". Recommendations are there for good reason, such as don't use racing slicks (because that lateral g you can pull on these tires may cause oil starvation and engine damage) you can also choose to bed brakes in or not bed brakes in. All these recommendations make a difference to both the long term and short term performance of your car.

These are daily drivers not some race engined specials where engine life is measured in hours

 

Interesting.

I asked how the guys at the Silverstone PEC ran in their cars and the answer was that they did about 300 miles of “normal driving”, then put them on the track to be hammered all day. No special servicing, just tyres and brakes need changing more often.

I suppose at the end of the day the run-in procedure you follow is the one you feel comfortable with, depending on how much mechanical sympathy you possess. 911 engines AFAIK are dyno tested at the factory, so they are not totally fresh from assembly. I suspect there is a very wide range of run-in schedules that will not affect the power delivery or longevity of the engine in any significant way.

Like diarrhoea, this thread will run and run...

 

Actually the factory no longer dyne's every engine. They stopped doing this years and years ago. I thought this too until a few friends did a factory tour back in 2011 and asked about this.

 

Those Porsche cars at the PSDS in Birmingham...are not broken in per the owners manual. I've done all 3 schools there and drove cars with a few hundred miles on them...and every car I drove in the schools had under 2000 miles on them.

The last 4 911 cars I've had that I tracked (997's) I did long drives and varied the rpms from 2000-5000rpms and did 1/2 throttle and some full throttle fast acceleration and deceleration for around 1000-1500 miles. Then I changed the oil and hit the track. All the cars ran great.

My 2009 (9a1 engine with pdk) drank oil like a 2 stroke. Basically a quart every 700-800 miles and at least a quart for 1 track day. Porsche PCNA and the dealer were notified but would not do anything about it. Said it's normal. I didn't push it because I was keeping its year to year and a half only. I tracked the heck out of that car and traded it for a 2012 GTS. My 2012 (9a1) got the same break in and didn't drink oil. My 2017 is getting the same break in and so far at 1200 miles is not drinking oil.

 

I developed this chart from reading the many threads on break-in and the comments of AP and other Porsche techs quoted in those threads. My understanding of it all was to vary the load while generally increase revs by 500 each 125 miles or so. I though they all implied that by 1500 miles or so "you're done".

The chart gave me an easy to use cheat-sheet that I used over a few long drives.

Of course, honor all the sage advice about warming up first, not lugging, vary the load, and wear a grin at all times.


Under 300 miles, do not exceed 4000 RPM
Under 425 miles, do not exceed 4500 RPM
Under 550 miles, do not exceed 5000 RPM
Under 675 miles, do not exceed 5500 RPM
Under 800 miles, do not exceed 6000 RPM
Under 925 miles, do not exceed 6500 RPM
Under 1,050 miles, do not exceed 7000 RPM
Under 1,175 miles, do not exceed 7500 RPM
Under 1,300 miles, do not exceed 8000 RPM
Under 1425 miles, do not exceed 8500 RPM

 

A surprising tidbit from from my factory tour of Zuffenhausen in June, I was quite surprised to learn that only 3% or fewer engines built there are dyno tested. Every engine gets a "cold test" where it is turned by a motor and various things are checked. Nobody knows for sure if that engine is going to run when they start it to drive it off the end of the assembly line.

When I asked the guide for more details I was told that at the rate they build engines for just in time installation at both Zuffenhausen and Leipzig plants, there simply isn't time to dyno test every engine. Those days are long passed. Porsche statistical data has shown an acceptable "failure rate" or number of "engine problems" using these processes.

 

Supposedly all of the 991.2 GT3 motors are getting a "hot" brake-in at the factory...