What are you thinking when breaking in your new engine?

[Guest Swifty]

I've only ever broken in ONE new engine in my life...so far. But I came across this article in the Wheels section of a newspaper and found it interesting. It might be wise to keep this in mind when breaking in your NEXT new engine.

 

The sole purpose to the break-in procedure is to seal the piston rings to the cylinder walls. This can only happen with high combustion pressures, and these pressures happen when the engine is forced to accelerate under load.

In a perfect world after a new engine is installed in a given vehicle, the vehicle should be driven on a vacant airport runway. The drive should consist of full throttle acceleration from a stop to approximately 60 km/h then brought down to about 15 km/h – with the throttle closed. Followed by another acceleration run to at least 60 km/h, followed by another deceleration to 15 km/h. This accelerate/decelerate process should go on for about 50 kilometres.

During the acceleration period, the piston rings are forced squarely against the cylinder walls, which trues them to each respective cylinder. In effect, the rings will conform to the shape of the cylinder.

The deceleration period creates a very low pressure in the cylinders (relative to the full power combustion pressures) and in the intake system. This low pressure is exposed to the cylinder valves and the oil that gathers in and around the valve guides. This low pressure (essentially a vacuum), draws this oil past the guides and into the engine cylinders. This helps lubricate the cylinder rings in excess of normal operation. The rings need extra lubrication because of the excess friction created by the break-in process.

[Monty]

I have broken in many new engines. My view has always been to break it in like it will be driven. Another philosophy I have is...it's under warranty now, and better to have it break now. Run it hard. If it's not put together right, it will come apart. if it's built right, it'll hold together. Of course, this philosophy comes from many years of drag racing.

[Squeeze]

Exactly what Monty said.

 

 

In Regard to the Explanation, creating a Vacuum also clears the Shavings in between Cylinder, Piston and Rings

[Squidley]

The biggest thing I have always done is not to keep it at the same RPM/Speed for an extended period. I'm also with Monty in the fact that I'll drive it like I normally will, and that may embellish a few speed limits from time to time....not that you'd know about speed limits Dave

[Eck]

Dave, ride it like you rode your old bike.

(Unless your scard...........)..

Ride it in the mountains, back roads, curves (if you have any up there)...and the engine will be constantly fluxuating in RPM,s and loads..all the while you are enjoying your seat theropy...

Dont forget to pass a few cars on the interstate....if yours will go that fast.

[dacheedah]

Drive it like you stole it http://www.mototuneusa.com/break_in_secrets.htm

 

I have a couple friends who drag race and one stock car, they all say drive it like you stole it will give you a better motor life and a higher hp in the end.

[Yammer Dan]

All good advice. I've built several and for some reason I felt I had to baby them about the first 25 miles or so. WOT then and drive it like I stole it for about 100 miles. If it was still going then drive as usually do. I've had one rebuild blow. Rod came apart and I had looked them over very carefully. Always wonder if I missed seeing something I should have.

[Dano]

This all is a GREAT way to break them in, have done it this way since the middle 70's, so yea it's the only CORRECT way to do it.

 

 

 

 

 

 

 

Plus it helps in exercising the lower portion of the body when you're keeping the foot planted to the floor.........

[SundayRider]

When I was flying we had the engine rebuilt and I was told to keep the power up to keep the rings tight against the cylinder walls. I guess a few guys around the airport had glazed their cylinder walls from running their engine to easy after an overhaul.

 

Also used to work for a guy who bought a new Chevy truck and went straight to the sand dunes and romped the heck out of it. Best running 350 Chevy I ever drove.

[Yamamike]

The biggest thing I have always done is not to keep it at the same RPM/Speed for an extended period. I'm also with Monty in the fact that I'll drive it like I normally will, and that may embellish a few speed limits from time to time....not that you'd know about speed limits Dave

 

Exactly right Squidley...the very worst thing you can do to a new/rebuilt engine is run at a set rpm for extended periods. Drive your car like you have a Yoyo tied to your big right toe!

[DarkLeftArm]

The "drive it like you stole it" method is good advice. Trouble is, at least with automotive engines with flat tappet cams, is the cam break-in. Cam manufacturers want you to use their high zinc content break in lube, and upon initial startup run the engine at 2000 to 2500 rpm for 20 to 30 minutes. That is always nerve racking for me. Everything about the install has to be perfect, and then to worry about the piston rings seating...