New Engine Break In Procedure Advice
 

I have a stock 3.0 motor which was modded to run with ITBs and has been dyno tuned, but I am just about finished updating with new pistons, rings, and cams.

So I need to get it back to the tuner; will I be OK to start the motor to do the 20minute cam break in?

The tuner advised that a 20 minute run at constant rpm isn't good for new rings etc. but I am pretty sure the cam break in is a critical process?

The change to the engine was from 8.5:1 pistons to 10.2:1. Also, went for a S type cam. I know the tune will need to be changed, but do I run a risk of detonation etc if just doing the cam break?

What do others do?

The cam and rockers get priority as far as I can tell.

If the cylinders are prepped well, the rings will seat in a period of time measured in many hours/miles

Actually, if the cylinders are properly prepped and you have precision rings they seat pretty quickly

I had good luck with deglazed nicasil plated cylinders and Total Seal piston rings. Seated well enough in the first 20 minutes. Very little oil consumption.

I may be wrong, but 2000 idle without load can be pretty lean without causing an issue.

Do you have a means to measure AFR yourself?

Car has a wideband and pretty sure the Infinity software does display on laptop screen.

Get it running and adjust the mixture during the cam break in. Then drain the oil and start the ring break in process. I like hard load that is constantly varied. Usually WOT to your rpm limit then hard off-throttle coast down. I raise the rpm about 500 every 15 minutes during the first hour starting at 5000 initially. This is assuming there are no weird noises or any other issues. With the EFI you should be tuning the engine during this entire process.

If you(or your tuner) are doing this on a dyno then the process is almost the same. You limit the rpm based on the dyno output and are varying load while you tune the fuel and ignition bins.

thanks, some good info there.

If it was “dyno tuned” as your post says then the first 20 minutes are gone anyway........