A friend of mine who used to race motorcycles professionally (AMA Pro Thunder) used break his motorcycle engine in by immediately driving the stink out of them. As in right as soon as he got them...Interestingly, his bikes would ALWAYS dyno higher than comparable bikes. We used to joke that this was the "Italian tune-up" (we ride Ducatis). Now it seems that he may have been on to something:

http://www.mototuneusa.com/break_in_secrets.htm

I realize that this will probably start a debate, but my mind has been made up

 

In my early years I sold cars for a pleasure. We got demos in those days and I broke in a lot of new cars. Being that I did not own or have to pay for them, I drove them all like I stole them.
They always ran strong and had no issues. I also drove many trade ins and other units, most struggled at WOT. They smoked, sounded bad and did not pull well. I think they should be driven early like you want them to run. A few hundred miles of varying speeds is not a bad idea but, i would not baby a motor long.

 

I don't have the answer for a car engine, but on my dirtbikes I typically run two very short heat cycles (10 minutes max) with cooling in between. Then run the snot out of them. Never really had any problems.

 

I drove my GT3 hard right from the dealer. I never came across one that ran better than mine did. In back to back dyno runs, it actually made 15 more HP than one that had a europipe exhaust on it.

 

I wish someone would do some scientific testing on this topic. I also wish we could get some engineers to explain why the manual says to break them in differently than most engine builders' techniques.

When building Chevy smallblock motors, there are 2 break-in scenarios to follow. First, you break in the cam by varying your RPMs from 2,500-3,500 for 20 minutes. Change the oil. Next, you focus on the rings. You put it on they dyno or road and perform a series of full throttle runs, followed by full decel.

 

If it is a rebuilt motor it all depends on what has been changed. If you have put new cams and rockers in then you want the 20mins of high idle 2000-2500rpm. If you are just seating in new rings, drive it hard. You need to put pressure on both sides of the rings through load and in gear decelleration. But, do not let the motor get hot, make sure you keep the oil temps in check. The mototune fellow has it spot on for breaking in new rings. Accel and deccel in gear.

I have broken in 5 motors this way in the last 2 years with good results.

As a side not, although maybe not relevant.... 2 folks I know who rebuild HD desiels (busses and trucks-detroits and cats) put them on the dyno and run the absolute $hit out of them for the first hour of their new life..... they even dead rack the govenor. They make their living rebuilding this so if it did not work, I guess they would not work either.....

Cheers

 

When we did the factory tour in '03 we went to the engine assembly area and got to see the various engines being manufactured. We were then brought to the dyno area where all the engines were tested for about 20 minutes according to our guide. I can tell you by the beautiful sound comming from the area that they were run above 4K.

After we picked up our car and were headed out of the factory we fell into a line of cars being road tested by Porsche employees and they definitely got on the throttle and left us in their dust. Apparently the police in Zuffenhausen have other things to worry about!

Although I don't know for fact I have never heard of any Porsche race motors ever having any break in procedures other than to drive them hard.

It has been my personal opinion that the 4K RPM break in procedure reccomended by Porsche has as much to do with getting the driver accustomed to the car than breaking-in the motor.

 

I'd generally agree with what has been said. If the cams/rockers are new, then you really need to run in the engine for the components to wear together. Something like 20min at 2500rpm is the norm. Once that is complete, or the engine has one complete heat cycle, I stick them on the dyno and beginn mapping the engines up through 4k with significant load, but not full load, especially turbocharged engines. I like to give some time on the engine to allow the cylinder pressure to wear the rings into the cylinders. After 1/2 hour or so, I map the rest of the engine operating ranges and treat it like an "seasoned" engine.

WRT to a new car. By the time you get the car from the dealer, the engine has already been run awhile, and most performance manufacturers like Porsche have road tested the car (hard) so I think the break-in is more for warranty and to pick up any small issues that may arise than for engine "wear in".

 

I would still like to hear from Honda, Porsche, BMW and all the other car makers explain why it says to take it easy in the manual.

 

So for a stock 944 race motor with new rings & new rod bearings, but same cam, etc what would be a good plan.

1) Run for 10-15 min idle to 2k no load?
2) Change oil?
3) run 20 min track session 6k max revs 3/4 load?
4) run 20 min track session 6k max revs full load?
5) Change oil & filter?
6) go racing?

This is a guess on my part... any other advice. It the above plan way off?

 

I think the easy break in in the manual is a liability issue - especially for high performance cars. They want you to get used to the car.

 

I only have one data point - after rebuilding my engine (new cams, refurbed rockers, new rocker bushings, new rings, new rod bushings, all new bearings, etc) I did the 20 minutes at 2-3k rpm, changed the oil, then sort of followed the mototune guy's advice and basically floored it, winding it up to 4K rpm and then letting it compression brake down to 1500rpm, repeat repeat repeat. People must have thought I was on crack. Changed oil again at 500 miles and also never went over 4k rpm until I hit the 500 mile mark. The engine had no compression or leakdown problems before and I made no significant mods, but the difference in power was very noticeable - and before my "incident" at Laguna I could easily pull a '91 equipped with plastic intake, lw flywheel, Wong chip, that was also carrying less weight, that put down a "corrected" 250 to the wheels. I think there is definitely something to this, but I would be wary of redlining it. I arbitrarily chose 4K as the limit.

 

I'm assuming that with a new Porsche engine, (engine only and no car), that Porsche tests the engine HARD before sending it out. Thus, once in the car,it can be driven hard? Also I would assume that since Porsche would have drained out the oil before shipping, that there's no need to use any thing but, say, Mobile 1, and run it for a regular interval with that same oil? What do you think?

 

With a new Porsche you are also breaking in the transmission among many other things.

 

During a club dyno day, one of the guys at the dyno shop said that he would run the snot out of the car when new. Something he picked up from a racing team when he was younger. I can't remember the procedure he did, but it had to do something both with speed and when going up hill for certain periods of time, etc. etc. etc. It almost sounded like the procedures when bedding your pads to the rotors, but longer.

When his car went onto the dyno, it registered 12-15 HP higher than other cars in its stock form.