How to break in rings on a 930 Turbo... What do the experts say?

[x98boardwell]

I own an 87-930 and recently did a top-end job including honing the cylinders and installing a new ring set. I did not touch the case in anyway during this top end other than installing new master link chains and ramps.

Here is the link from the build with pic's. Updates on engine top-end rebuild

I have heard a few things and am curious on what the experts think. I use the word experts because I would like feedback from the guys who have seen this in the real world... not someone who heard it from a buddy.

1) I was told to go easy for 1,000 miles with no boost.
2) Go easy for 1,000 miles and introduce boost occasionally (around 1 - 2 10ths bar) to help seat the rings with higher pressure.
3) start driving like normal... the boost will actually help seat the rings by forcing them to push against the cylinders under load... my buddy told me this, hence the reason for this thread.

I am using normal (non synthetic 20/50) oil for the first 1,000 miles and plan on changing once around 200 to make sure there are no metal chunks that I need to know about. Also, I realize that my car is a relatively low compression motor around 7:1 or 7.2:1 or something around there. I am guessing that when boost is introduced the compression rises to around 10 or 11. Now, an SC motor is around 9 or 10:1 and their compression is always that high. So, whats the difference if it is compression from boost or from the pistons normaly?

Lastly, when people purchased these cars back in the 80's the dealer or Porsche did not tell them to "baby" the car for the first 1,000 miles did they? I bet they left the lot sideways if they had LSD. This is what may have lead to short engine life but I am trying to figure out what is best based on experience.

Your input is appreciated.

Thanks,
Bryan

[Rusty 356]

Bryan, get the engine to operating temp, then start applying light steady loads. Starting low loads and work your way up. Rebuilding engines and running in on the dyno is done very much the same way. Taking it easy for a 1000miles with little or no load is a mistake.
I'm just another Porsche nut that has built a number of engines and have been in the engine business since college and I'm not a youngster. Opinions may vary.
Good luck, hej, and if you have a chassis dyno available, do it that way.

[mppickett]

I used the method described here: http://www.mototuneusa.com/break_in_secrets.htm

Using non-detergent dino oil, I warmed the engine up and then ran at high throttle (no boost) up to around 4000 rpm and then let off the throttle fully and let the engine brake the car. I repeated this many times.

[smokintr6]

I recently did a top end on a 3.2L carrera, and used a break in similar to the link from mototuneusa. I personally believe bursts of acceleration and deceleration are essential to a proper break in, and have used that strategy on all my rebuilds. One thing that generic articles don't take into account is that there are many different types of cylinders and rings. Many top compression rings have a beveled inboard edge which uses the force of compression to push the rings outward onto the cylinder. This is why some builders suggest high throttle applications while the honing pattern is still fresh. One issue that I have never seen anyone address is my concern that it may be easier to overheat new rings in a boosted engine, because there is positive pressure on the piston during all four strokes (granted that the pressure during the intake stroke is miniscule compared to that of peak cylinder pressure, but it is still there, and would not be on an NA engine). I'm not suggesting that this is the case, but it is something that I have pondered. Does anyone know if nickasil vs. alusil cylinders should be treated differently during this process? I personally have not replaced rings on an alusil engine, but I see this as a pontential concern becasue the composition of the metal in the rings, and cylinder walls are completely different....along with the honing or cleanup process. I have probably wasted too much time pondering this, as most likely I will continue with the process I have always done.

x98, another thing to remember is that open throttle operation on a new engine does not mean high load at low engine RPM. I like to be between 3k & 4.5k at first on a new engine. Then progressively work a little higher.

[RSTarga]

vary your engine loads for the first thousand not exceeding 5000rpm, after that change your oil and drive it like you want to.