73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: jaysons on November 26, 2010, 12:34:20 am
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I found this on another forum & found it very interesting. Thought I would share it!
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What's The Best Way To Break-In A New Engine ??
The Short Answer: Run it Hard !
Why ??
Nowadays, the piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber.
If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of
PSI (Pounds Per Square Inch) of combustion pressure ??
Of course it can't.
How Do Rings Seal Against Tremendous Combustion Pressure ??
From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into
the cylinder surface, to seal the combustion pressure as well as possible.
The Problem With "Easy Break In" ...
The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run.
There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!
If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.
Fortunately, most new sportbike owners can't resist the urge to "open it up" once or twice,
which is why more engines don't have this problem !!
An additional factor that you may not have realized, is that the person at the dealership who set up your bike probably blasted your brand new bike pretty hard on the "test run". So, without realizing it, that adrenaline crazed set - up mechanic actually did you a huge favor !!
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This is what I was told .......
From what I understand, It is VERY, VERY important to allow the engine to reach full operating temperature first. Then I was told to bring the rpm's up, through each gear, at different intervals. And allow some "engine braking" as well, when you let off the throttle.( Let the engine slow you down).
I was told to warm it up for about a half hour or so, shut it off & check the oil, & top up if necessary. then start it, & allow it to completely warm up again,( should only take a few minutes at this point), then get on the road & bring it up to 20 km's/hr or so,( in an aggressive manner), then let off & come to a stop. Then take off again & bring it up to 40 or 50 km's/hr., aggressively, & again let off throttle, allowing the engine to slow you down some, & come to a stop.
Keep doing this, in this manner, increasing at 20 or 30 km/hr increments.
Apparently, the rings will seat the best at abrupt, different rpm's. (as many as possible). But the fuel pressure behind the rings, (as mentioned above), will create a better ring seal if there is as much deceleration pressure as acceleration pressure, creating a sort of "reverse" pressure & not just a "thrust" pressure.
Jayson
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That is the way we always break in our dirt bikes let them warm up shut them down, fire them up cruise for a lap or so then just let it rip, never had any problems with any motors. you either have the rings right or you don't if they are right it wont matter if you run it hard in the beginning.
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The thing to remember too is that a motorcycle engine and a truck engine are used in two different applications. Meaning, a moto has a higher power to weight ratio where a truck has a much larger load. Ever pull the front end up on a square body? You can do it in first on many sport bikes (even twins) and prolly clutch it up on ALL of them.
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Ever pull the front end up on a square body?
This is my ultimate goal!
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If we are talking about breaking in a conventional reciprocating 4 cycle engine with a flat tappet cam #1 you need to break in the cam. #2 you need to break in the rings. With so many different types of rings on the market now you really need to follow the ring manufacturers break in procedure as it varies but we've discussed this many times here if you want to use the search to see more detailed posts
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I broke in my last engine build (Honda stock build) using the Motoman method. I am very pleased with the results. It runs smooth and strong, vacuum is great and oil pressure is awesome.
http://www.mototuneusa.com/break_in_secrets.htm (http://www.mototuneusa.com/break_in_secrets.htm)