LQ9 Engine Rebuild and Break-in Questions
 

Hi everyone,
I hope that I am posting this within the correct forum, and/or not repeating another post. If either of those is happening, please kindly redirect me. So right now I am in the process of doing a mild performance rebuild of my truck's 6.0L/LQ9. I am replacing all bearings, bigger camshaft, new lifters, new pushrods, new roller-rockers, 11.1 compression pistons, 34lb/hr injectors, longtube headers, some cylinder head reconditioning, and whatever else the engine needs to have done to be like new again. So my question is about break-in procedure and how to do that. I already have a very good shop lined up to do the tuning on a dyno. But, I am worried about breaking the engine in prior to doing dyno pulls with it. Seems too aggressive to be happening right away. My fear is that the stock tune on the truck will have this engine, with all the new mods, running very badly, which is also not good for breaking in a fresh engine. The tuner I am using tunes only from a dyno, so he cannot send me a rough file to put on the truck for this. If I am overthinking this, please tell me lol! Any and all thoughts and ideas are appreciated! I just lack experience.

People can do what they want but to me the engine is "broke in" after a little bit of run time. It will either work or it won't. Doing a 500 mile break in isn't going to make the engine last any longer than if you only waited 5-10 miles. Think of how many times the pistons/lifters have gone up and down as well as how many times those bearings have made the right around the crank/cam shaft in just a short amount of time.

You'd have to trailer the truck there if you put in those larger injectors. It will run horrible and could wash the cylinders with fuel. It should start and run much better with the stock injectors even untuned if you drove it there.

Yeah I know there are a lot of varying opinions on engine break-in, and I do not want to inadvertently start an argument over that lol, but I really appreciate your input. The injector issue is something I was concerned about too. Thank you for clearing that up!

If the piston rings are cast with no coating they seat almost instantly. By the time the tuner works his way through the correct fuel map and timing the new engine should be ready for full throttle pulls.

On all the engines ive done all i do is throw in a startup tune and heat cycle the engine one time to check for any leaks and make sure everything is in working order. Once that is done i tune fuel tables first then tune spark tables. So within the first 30 mintues its seen the rev limiter a couple times.
If it has good oil pressure and coolant temps are in check either it is gonna be a good one or a bad one :)
Wiring up a Turbo Dart 427 in a Fairmont and once i get the idle sorted out its going straight to the race track tomorrow night and it will get the crap beat out of it on 30+ PSI.

The old school break in with flat tappet cams and such are long gone.

Last year a guy drove his truck to the shop for me to tune and he was still on the stock tune but with a 3 Bar MAP and 80# injectors. After talking to him a few weeks before he was trying to run it with 1 bar map and LS9 injectors on stock tune. :(
By the time he got here it was running really bad. Ended up washing the cylinders and would barely crank even with the lower cylinder pressure.
He had to pull the engine and get the block honed and some new rings. I never seen one scar the cylinders like that.