Most likely not broken in properly, I think there's no need for in depth intellectual debates on this because we all know how people are, if it's not theirs to keep for a long time, they simply do not care about the next owner.
I didn't say they were broken in, I said "...as most cars are ran for a period of time by the manufacturer" which is still true.
As soon as a car is brought off the production line they are brought onto a rolling dyno, ran through their paces, some even have a "test track" to drive the car on and find rattle squeaks and things. If you watch some production car videos you'll usually catch it at the end. I believe there is a Mustang video taking the car to 110mph and the didn't "follow the break in" there.
No matter if the car was built in 1920 or 2020 a break period is always a necessity to make sure the engine performs optimally. If it has an internal combustion engine, a break in period is essential. Piston rings and cylinder linings take time to take shape. The manufacturers run them hard after assembly to get them out asapā¦.but realistically itās not enough time to properly break them in, it would be impossible for them to make any money putting out cars that late after production.
That depends on a lot of factors. Like what Ra is the cylinder honed at? What material are the rings?
Itās not just rings and Ra finish, itās the block distortion that changes the cylinder shape at various phases of the thermal change. Aluminum blocks have a greater spectrum of bore distortion (unsleeved) than a cast iron block from cold start to operating temps to high temps. This spectrum of change plays a big role in how the engine breaks in throughout the many cycles. So, while most tuners will say to run the motor on a dyno very hard after a rebuild, their blocks are probably prepped for little distortion than an off-the-line motor from the factory. Ra finishes of spray lined bores wonāt prevent the rings from settling incorrectly in a bore, but letting a spray lined bore still needs the same brake in attention as any other engine to let all the moving pieces become āfamiliarā in their environment.
I mostly deal with factory aluminum blocks, so I get the distortion part. That's the 20% I'm talking about. Engines run at operating temp most of the time so it takes many heat cycles to get that last part broke in. As for the sleeved part, you talking wet or dry sleeved? Not a fan of wet sleeves so when it comes to that point, it's straight to an aftermarket block so that you get a nice thick sleeve but it's still surrounded by aluminum.
