Chevrolet Corvette Stingray C7 Forum - View Single Post - The BEST Break for a new car. "very long"

Iron Lung Jimmy · 12-17-2009, 05:16 PM

Disclaimer: I haven’t bothered to read this whole thread so if this has already been addressed, oh well…

IMO, anybody who ignores the owner’s manual and breaks in their Camaro based solely on what some guy on the internet writes is an idiot. Harsh? Maybe… but true.

The OP’s claimed credentials are that he has been building engines for 25 years. So what… things change. How many LS3’s has he built?

Then he states that the method described in the owner’s manual is written as legal cover… which is absurd. If the proper method of breaking in your engine was to do a bunch of hard acceleration runs, sure, GM would not want to print that. But neither would they print the exact opposite… they just wouldn’t print anything. Since the Mustang debacle of a few years ago manufacturers are very aware that their engines have to produce the advertised power. There is no way in hell GM would recommend a procedure that would compromise their engines ability to produce the advertised power.

If GM tells you to go easy for the first 1,500 miles… when if it was necessary to cover themselves legally they would be better off saying nothing… there really must be a reason. Who are you going to believe, the people who designed and built the car or some guy on the internet?

The piston to bore clearance in LS3’s is a negative number. That means the piston is slightly larger than the bore (we’re talking microns). As the engine breaks in, material is worn off the piston… the end result being a very tight tolerance. Armed with that knowledge alone, I am going to postulate that it either doesn’t matter how you break in the engine or that breaking it in slowly would be better. Since GM recommends slowly I am going with that since I see no downside. In my mind’s eye I would kind of like to see the piston material worn off slowly so the piston and bore get to know each other gradually and form a nice fit.

And even if it doesn’t matter to the engine, at least my transmission and differential will get a chance to wear in better.

I would love to hear from a GM engineer on this subject.

12-17-2009, 05:16 PM	#305
Iron Lung Jimmy Drives: Iron Lung, Jimmy Join Date: Jun 2009 Location: Louisiana Posts: 1,577	Disclaimer: I haven’t bothered to read this whole thread so if this has already been addressed, oh well… IMO, anybody who ignores the owner’s manual and breaks in their Camaro based solely on what some guy on the internet writes is an idiot. Harsh? Maybe… but true. The OP’s claimed credentials are that he has been building engines for 25 years. So what… things change. How many LS3’s has he built? Then he states that the method described in the owner’s manual is written as legal cover… which is absurd. If the proper method of breaking in your engine was to do a bunch of hard acceleration runs, sure, GM would not want to print that. But neither would they print the exact opposite… they just wouldn’t print anything. Since the Mustang debacle of a few years ago manufacturers are very aware that their engines have to produce the advertised power. There is no way in hell GM would recommend a procedure that would compromise their engines ability to produce the advertised power. If GM tells you to go easy for the first 1,500 miles… when if it was necessary to cover themselves legally they would be better off saying nothing… there really must be a reason. Who are you going to believe, the people who designed and built the car or some guy on the internet? The piston to bore clearance in LS3’s is a negative number. That means the piston is slightly larger than the bore (we’re talking microns). As the engine breaks in, material is worn off the piston… the end result being a very tight tolerance. Armed with that knowledge alone, I am going to postulate that it either doesn’t matter how you break in the engine or that breaking it in slowly would be better. Since GM recommends slowly I am going with that since I see no downside. In my mind’s eye I would kind of like to see the piston material worn off slowly so the piston and bore get to know each other gradually and form a nice fit. And even if it doesn’t matter to the engine, at least my transmission and differential will get a chance to wear in better. I would love to hear from a GM engineer on this subject.