Racing Engine Break-In Procedure - Break-In Basics

After 20 minutes on the first oil fill, the filter and oil are changed. Again, use a good mineral oil along with a quality filter for the second round of the break-in. This next fill should be run for about an hour to maybe an hour and a half with the engine progressively cycled to higher rpm. The engine should be up to about 75 percent of the rpm it will eventually reach. At this point, the sump should be refilled with the oil you intend to use during a race or dyno test. Make some provisional pulls once the engine is on the dyno. Work up to the redline to ascertain all is well, and then go for it.

Let's discuss in greater detail oils for break-in. EPA mandates placed on street usage oils have brought the removal of additives that are historically effective high-pressure lubes. This makes any off-the-shelf, street-type oil less effective as a break-in oil than it was just a year or so ago, which necessitates modifying this year's break-in procedure. As a matter of course, I always put Oil Extreme into the break-in oil. If you are not using a high-pressure additive, you might consider using a bona fide race oil as a break-in oil-especially if the motor is a flat-tappet cammed unit. Suppliers such as Redline, Joe Gibbs Racing, Royal Purple, and others have oils specifically blended for flat-tappet cams. The most critical time for a flat-tappet cam is the first 20 minutes. Such cams demand a lube with high pressure capability. If the springs have over 350 pounds of force over the nose, the cams need to be broken in with Comp Cams low-lift rockers and/or a softer break-in spring.

Cylinder Bore Specific Break-In LubesNow that we've handled the flat-tappet cam situation, it's time to consider the source of the engine's greatest frictional losses-the bores, rings, and pistons. A steady and lengthy break-in helps cut the final frictional level where the parts stabilize, and the same procedure also leads to the best cylinder seal. But there is something of a compromise going on here. We need a lube on the bores to cut friction and wear, but we do not need lots of oil in the upper cylinder or on the cylinder walls because the octane value of the fuel can be compromised and unwanted additional drag on the rings is produced. But the bores will experience more friction and wear without adequate lubrication, and we don't want that, either.

Here, it's worth taking a few pages out of Caterpillar's test portfolios. Quite a few years back, an experimental marine-sized diesel was giving the company severe problems with bore and ring wear. A rather unique and effective upper cylinder fuel additive was used, and the problem simply went away. I did some 250 hours of A-to-B tests on this additive about 15 years ago for an EPA report and found that in a worst-case scenario for the test engines concerned, ring and bore wear was axed by no less than 600 percent!

Here is how it apparently works. First, this additive (now commercially known as American Clean Energy Systems or ACES) must be mixed in very low concentrations with the fuel. When the combustion cycle takes place, the additive burns into a high-grade synthetic lube that coats the cylinder walls from the topside down with a lube layer just a few molecules thick. Remember, on the way down, the rings scrape much of the oil off the bores. The lube component is spread thinly on the bores with this additive, so on the way up, pistons and rings should not even touch the bores.

Over the years I have found this additive to be really effective at prolonging the life of rings and bores. Given a top-notch air filter, 2,000 racing miles result in near-zero wear on rings and bores. Last year, I tore down the engine from my GMC Sierra tow truck. The intent was to install a valvetrain and heads to complement the Magnusson supercharger that was to be subsequently installed. This engine had 106,000 hard miles on it (and I mean hard). I followed my own advice here, and as with all my other engines, the result was near-zero wear. This engine went back into the truck with the original factory rings and bearings!