I know some of you folks have reported piston failure because of the narrow stock ring gap closing up under high load pressure on some motors. If these these motors were broken in "by the book" could that be the problem? I have this idea in the back of my mind that aggressive, full boost, to the redline driving right from the get go (in short burst to prevent overheating and glazing the cylinder) would rapidly seat the rings and open the ring gap just a bit where "by the book" break in could just knock edge off the cylinder crosshatch and the rings never properly seating. Truth or BS?

 

Another good question is: were these engines given full boost before being fully warmed up? Not necessarily during their failure, but during other "operational cycles"? Unfortunately many factors could be contributing to these failures and sorting them out is VERY difficult...

 

Goes back to the old, should you break it in easy, or drive it hard so it runs hard?

 

Yeah, reading up on this controversy is what got me thinking, I broke mine in hard (Previously cars were "by the book") so far so good (13,000mi).

 

I thought this was interesting.

http://amsperformance.com/instructio...structions.pdf

I broke in the my car(s) the same way; made great power on the dyno and 0 issues. And this without beating the **** out of during the first ~700 miles.

It's a long standing debate.

 

Slow and easy my .02 cent.

 

after we built motor and put it in our 10.5 outlaw car. We hit the dyno and then the track.

 

To me (and im am NO expert) it doesn't matter these days..

I am pretty sure they run them at the factory for a couple of hundred km's, up and down the revrange different loads.

My 1st two IX's I did the gentle breakin, the X I basically hammered fullboost (but not redline) out of the dealership...

AS long as the car is HOT (engine and trans) then it doesn't matter IMHO...

 

I definitely don't think break in has any bearing on the failures. I am sure some were broken in gently and others rough, just like all cars.

 

Any input from folks who actually had this type of pistont failure?

 

Its just a data point, I do not know the mits. factory, but I have personally seen the " break in" time at the Subaru factory here in the states and the Ford mustang lines and the Break in time at the factory in both cases was about 3 minutes run time (under load) total. The subaru factory would pull one car randomly off of the line and run it on their track at the plant, but this was not even 1 out of 20 vehicles....

 

Break-in procedure can be dependent on the type of metal the piston rings are. 1G DSM 4G63's have chromium rings and in the Mitsubishi repair manual it recommends getting the engine up to temperature and then doing short bursts of full throttle (I think 35-50MPH) and then letting off leaving it in gear to let the engine pull vacuum and help seat the rings. In my experience iron rings are better broken in with the "slow break-in mileage method".

 

I agree with Tephra...almost all newer engines, especially performance ones are broken in at the factories on engine dynos.

 

Both Romeo and windsor engines (ford v-8, cobra and ford GT motors) were run hot out of the car for less than 1 minute. Only to do a compression and start test. The four cylinder plants I have been to also performed tests this way. The piston rings in todays cars have to seal almost instantly from an emissions standpoint. Talking with R&D drivetrain engineers from several sources say the rings in stock cars seal " by the time you get to the first stop light away from the dealership". That is with the motors not run on a dyno for ANY length of time....

 

I'm subscribed to this thread. Thinking about picking up a X this weekend. Good question. I will be breaking mine in until about 500-600 nice and easy but not driving like a *****!! haha But I won't be beating on it.