Well...... I did the Lance break-in on the 2004 z06..... now, with 4600
miles on it, I decided to have it dyno tested. I went to 21st Century
Musclecars, aka LPE Jr., who are known to have a notoriously low reading
dyno. They told me all the stock 2002+ Z06's there dyno 345-355rwhp..

Then we put mine on the rollers... dyno chart here:
http://www.boostaholic.com/z06

"This is from a post to another list originally made 9/16/1999. I have been using this procedure for many years (at least 18 years). I both agree and disagree with the link you posted. I'll explain why after you see my procedure.

I have a standard break in procedure that I use, it takes about an hour if you are diligent, and when you are done, break in is complete. The biggest point of grief with a new engine is the unrelieved stresses in the pistons. You want to heat and cool them in a predictable way with an incrementally increasing thermal load. I usually start at 20% throttle and go in 10 or 15% increments until I get full throttle. Bursts should be 15 to 30 seconds, followed by 5 minutes part throttle cruise to let the pistons cool and resize themselves. You can figure out that 30 seconds in top gear at full throttle will have you going pretty fast down the road, so you need a clear stretch to do this, but I have never had a problem with leak down or bad piston fit using this technique. That crap about "XXX" miles is just so the average driver doesn't blow things up.

Also, I assemble the cylinders dry, but turn the engine over for about 15 seconds with no fuel or ignition before my initial start up, then I run it up to about 25% of redline as soon as it catches for 30 seconds or so. Once I have my initial 30 seconds and no gushing leaks, I take it out for a drive right away. I want to put pressure on the rings and valves to get them to seat well and that can't be done without a load, so off we go down the road for about 5 minutes, then return to the shop to check for oil or coolant leaks. If all is OK, back out on the road for final break in.

OK, that's what I have recommended. I disagree with Motoman because he is ignoring the whole issue of grain structure in the pistons. If you are using used pistons, then there is no need for any kind of loading tactics like these, just a few full throttle runs at soon as the oil is up to temperature to seat the rings and you are done. Cast pistons have not aligned their grain structure after casting, and forged pistons have unrelieved stresses from the forging process. Both require heating and cooling cycles to allow the grains the opportunity to align themselves under thermal load. It isn't possible to do this in the manufacturing process because pistons are not heated evenly in service. This process is no different than heat cycling your tires, a well known science among racers. I completely agree with Motoman's assessment of the manufacturer's recommendations. They are crap. I also completely agree with getting a load on the engine as soon as you can. I didn't notice any admonishments about allowing a new engine to idle, but I NEVER allow a fresh engine to idle, it is the kiss of death IMO.

Ken, in your situation, you have little or no control over how the engine was initially fired, and BMW being reasonably intelligent and diligent have already used an initial firing procedure designed to seat the valves and rings quickly. Just take it out and drive it, put a load on it, and be happy with it.

Lance
'93 TT 6 speed Coupe"