Engine Break In

What is the best way to break in a rebuilt motor ? I've read everything from hard initial driving to set the rings to easy going right from the start with pre set rpm limits.

I purged every last available dollar to my name to get my car out of the speed shop. It's finally home

Awesome dude. I'm glad to see a lot of the older members coming back around...

I am going to have my car running by next week also here and will be breaking it in. I've done a lot of research on this and think I know the best way to get a good running car that will still last a decent amount of time... Variable RPM's is a must. Avoid highway driving at constant steady speeds. Drive the car semi-hard but only up to 4k RPM's about... I say drive it semi-hard so that you can build a good bit of boost to help set things in place, but without taking into the higher RPM's... That should make for a strong running motor and still give you a decent amount of longevity out of it too. :thumbsup:

At least that is how I'm gonna do it. lol...

Info was taken from the 2gnt site.

1: The best way to get the rings to properly seat is to go out and do FULL rpm range pulls (after letting the car warm up with normal operating temps of course). Most people recommend finding a nice long stretch of road and doing between 15 and 20 third gear pulls from low rpm to high rpm. For some this means 2k-5k, and for others this means 2k-redline. Regardless of the semantics of exact rpm range, go out and stress the engine. Allowing the car to engine break a little bit between pulls is good too.

2: No matter what you do, the engine isn't broken in until you have run it hard. Driving 1000 miles with no boost is basically like not having driven it at all. The rings still are not seated so at 1000 miles, it is basically like driving it hard from the start, but you wasted all that time driving around slow for nothing. Actually it may be worse for the engine as you seat the rings improperly and you get massive oil blowby and lower compression than there should be.


Be smart and change the oil often. Most likely I'll change at 30-50 (to check for metal wear and anything else abnormal), 100-150 and again around 500, all with conventional oil. Some say to stick with normal oil until over 1000 so it's up to you when you switch over. Since the rings seat basically in full by 30 miles, but still need some time to completely finish the process in full, sticking with conventional oil is a good idea for a while.


The theory behind it is this: Getting on the engine is good for it, as stress on the new parts is what is needed to mate them to each other most efficiently. This is counter intuitive to us humans as we like to keep things pristine and unworn, but an engine needs wear, strees, and nasty stuff like oil and lube to run right. It needs the stress of an aggressive break in to run properly.

Another thing that is IMPERATIVE is this. Run as low boost as you possibly can, and MAKE SURE you do not knock. Knock is by far the worst thing for an engine, and is an accentuated problem for a brand new one. Run pig rich and the car will run terribly, which is fine. Just make absolutely sure you aren't knocking. Also, keep in mind that this is a controlled method and not just "beating" on the new engine. Go out and do it methodically and you'll be just fine.

Here is a good link that outlines alot of good research and points on the engine break in procedure. http://www.mototuneusa.com/break_in_secrets.htm

Nice feedback. I've been looking for a good excuse to put my foot in her.

I will be following that www.mototuneusa.com method possibly next week. Great link!

Let's get more in depth with this. I can definately understand the concept of breaking in hard off the bat to seat the rings tight. But what about every other moving part in the engine ? I wonder what would happen if you took a rebuilt engine and cranked it over some million times with another engine on a stand or an electric motor turning the crank. You could set it up to constantly change RPM levels without ever firing it up. Then proceed with the hard pulls to set the rings. What do you guys think ? :screwy:

Let's get more in depth with this. I can definately understand the concept of breaking in hard off the bat to seat the rings tight. But what about every other moving part in the engine ? I wonder what would happen if you took a rebuilt engine and cranked it over some million times with another engine on a stand or an electric motor turning the crank. You could set it up to constantly change RPM levels without ever firing it up. Then proceed with the hard pulls to set the rings. What do you guys think ? :screwy:
dont know on this, but i'll bet that because of the heat differences between a running motors internals, and the internals on a motor done this way, that i will more then likely be pointless... when i got my new motor, i pushed it hard off the bad and ran 8 psi on the T-25.... on a EX civic coupe ;)

You only "break in" the rings. The bearings are where they need to be and don't break in with each other.