Break In Procedure for New Engine

I've heard a number of different ways that a new engine "must" go through or you'll ruin it. About the only consistent idea is not to use synthetic but even that differs on the time period until you are able to use it.

Anyone think they have the proper way to break in a new engine?

There you go... both sides that are seemingly opposites. One book says to idle for 20 minutes then put in synthetic and drive to your heart's content. One says to idle for 15 minutes, change oil and do the 500 mile break in THEN put in synthetic. My other book says keep the RPMs fairly high so the rings will seal (especially important on chrome moly)... so there ya go.

I was finally able to get a hold of a friend who has put together MANY a performance engine and got his opinion. He told me to make dang sure everything was primed and as close to final final specs as possible before cranking it up. Immediately upon cranking take it to a fast idle (1000 - 1500 RPM). Run for 30 - 40 minutes at this range with an occasional bump to 2000 or down to 800. While it's running check out the engine thoroughly, check for leaks, check timing, etc. Unless there is a serious problem continue running for the 30 - 40 minutes before shutting down. Change oil and take it for a spin at normal conditions. Normal I guess would be your average Joe taking it on a grocery run, and go for a few hundred miles. He said you'll be able to feel it getting stronger as the rings complete their seal and the cam is broken in. Not so important on a roller cam as a flat tappet but important still.

So I guess this is what I'll do. Thanks for your help guys!

Do you HAVE to do this procedure? Probably not. Am I GOING TO do this procedure after investing more money than I care to mention in this engine? You're damn right I am.

You need to keep in mind that the cam is not the only thing that needs to be broken in. Virtually every aspect of the engine is liable to change slightly, heck even the crank will change it's shape but then we get into negligible amounts there. It's true the break-in procedure doesn't really apply to hydraulic rollers but like I said, there are more things that are adjusting themselves.

One important aspect of the break-in is the cylinders. You want to physically wear the new piston rings into the cylinder wall until a compatible seal between the two is achieved. When the engine is running, pressure is present in the cylinder behind the piston rings and it's force pushes the piston ring outward against the cylinder wall. The higher the pressure, the harder the piston ring is pushed against the wall. The surface temperature at the piston ring face and cylinder wall will be greater with high psi than with low psi. This is because you are pushing the ring harder against the rough cylinder wall surface causing high amounts of friction and thus heat. The primary deterrent of break in is this heat. Allowing too much heat to build up where the ring and cylinder wall contact will cause the oil that is present to break down and glaze the cylinder wall surface. This glaze will prevent any further seating of the piston rings. If glazing is allowed to happen break-in will never occur. You must achieve a happy medium where you are pushing on the ring hard enough to wear it in but not hard enough to generate enough heat to cause glazing. If glazing should occur, the only remedy is to re-hone the affected cylinder and replace the piston rings and start the whole process over again.

This was taken more or less verbatum from an aircraft manual which has an internal combustion engine very similar to an auto. The same is true of foreign cars. A car that is sold in Japan comes with very a very detailed break-in procedure, that same car sold in America more or less says to drive it easy for the first 1000 miles.

Not only do the rings mate with the cylinders but every bearing will elongate and mold to the surfaces, various bolts and studs will loosen up slightly, especially exhaust header and intake manifold bolts.

It's also very important to change the oil between 500 and 1000 miles at least, if not once before that as well as it will likely be contaminated with assembly lube and microscopic bits of metal worn off during the break-in process. Some people even say to remove the plugs and take a look at how they are running (lean, rich, etc). Good advice IMO.

Don't get me wrong, I think you are VERY knowledgable about engines and cars in general but I disagree with your break-in procedure. I agree that you should go out and drive it as soon as you determine whether or not there are any leaks or inconsistancies but you should not drive it like you stole it right out of the garage. As Michael said, go out and drive some, come back check things out and head back out again.

The only reason I harp on the rings is because of a previous experience. My brother and I rebuilt a truck and never could get the rings to seat and ended up changing them. I learned by experience to break in the rings.

As with everything related to performance though... everyone has an opinion, none of which is the best for everyone!

Thanks for the help guys, I'll let you know how things turn out.

I saw that page by Motoman as well and read through it. Decent page but I think you're right, he's not real concerned about longevity. Of course, neither are race car engines. Good advice all around. I had heard before that seals and rings will mate very quickly but wasn't sure about it. Looks like it must be true after all.

Thanks again for the help, I'll let you know how things go.