Break in period for a new z

ZoomZ · 01-26-2017, 10:52 AM

The subject of engine break-in is argued as much as the subject of which oil to use.

Honestly, everyone is right. As long as you use an oil, you won't hurt anything. As long as you drive the damn car, get it up to proper operating temperatures, you are doing it good.

What happens at the factory is engine RUN-IN a term which is often forgotten.

The belief that the engine is BROKEN-IN at the factory is a misleading one.

During RUN-IN, the manufacturer is only assuring the engine doesn't leak, meets their specs, and most importantly setting it up for the ultimate BREAK-IN by the user.

During the Run-in, there is inherent metal to metal and wear occurring. This is obvious. Some consider this Broken in. However, no matter what scenarios they develop in the test cell to replicate real world operations, they can never replicate actual real world scenarios.

In airplanes, we are told to take up to above 75% of rated engine horsepower for first 50 hours. (feels like an eternity) It is the scariest 50 hours for the pilot.

If we apply that convention to modern, liquid cooled automotive engines, we can probably accomplish the same thing.

So for a 350HP Nismo, 75% works out to 263HP. For argument sake, if we develop 350@7500rpm, 263HP would be around 5600RPM. Not too far off 4000.

Again, this brings back why Nissan chose 4000. (which work out to about 55%HP) Nice even number and you wont be babying nor destroying in extreme conditions.

Just a scenario, I'm not suggesting this is how it's done or actual math etc. Just my aviation scenario theorized for automotive use.

ZoomZ · 01-26-2017, 11:14 AM

Quote:

Originally Posted by Hotrodz

This is the only point that was made to me by a lot of folks that know more than me!

There is one more thing about piton ring wear, that for the life of me, I cannot find the drawings and explanations/details for.

In short, when you hold an engine at a constant RPM, the piston/rings tend to "Harmonize" in 1 spot on the cylinder walls. Causing wear on only this portion of cylinder wall.

By varying RPM, the pressure changes, and the piston/ring will "harmonize" on a different portion of cylinder wall.

I don't know if this makes sense and I wish I could find the illustrations to prove it.

Also, it may have only applied to cylinders which are 'choked'. Can't remember.

Magic Bus · 01-26-2017, 03:04 PM

Quote:

Originally Posted by Cyber370

You would think that if break-in periods were critical for engine reliability and longevity, car manufacturers would program lower rev-limits into the ECU for the first couple thousand miles or so.

In reading the BMW forums, it appears that they do it on their M cars. Till first service at 1,200 miles. Not sure if it's all their cars.

Hotrodz · 01-26-2017, 11:12 PM

Quote:

Originally Posted by ZoomZ

There is one more thing about piton ring wear, that for the life of me, I cannot find the drawings and explanations/details for.

In short, when you hold an engine at a constant RPM, the piston/rings tend to "Harmonize" in 1 spot on the cylinder walls. Causing wear on only this portion of cylinder wall.

By varying RPM, the pressure changes, and the piston/ring will "harmonize" on a different portion of cylinder wall.

I don't know if this makes sense and I wish I could find the illustrations to prove it.

Also, it may have only applied to cylinders which are 'choked'. Can't remember.

Agreed....that is what I have been told!

Sent from my SM-N910P using Tapatalk

01-26-2017, 10:52 AM	#31 (permalink)
ZoomZ Track Member Join Date: Jan 2017 Location: Vancouver, BC Posts: 761 Drives: 17' 370Z Nismo Rep Power: 40617	The subject of engine break-in is argued as much as the subject of which oil to use. Honestly, everyone is right. As long as you use an oil, you won't hurt anything. As long as you drive the damn car, get it up to proper operating temperatures, you are doing it good. What happens at the factory is engine RUN-IN a term which is often forgotten. The belief that the engine is BROKEN-IN at the factory is a misleading one. During RUN-IN, the manufacturer is only assuring the engine doesn't leak, meets their specs, and most importantly setting it up for the ultimate BREAK-IN by the user. During the Run-in, there is inherent metal to metal and wear occurring. This is obvious. Some consider this Broken in. However, no matter what scenarios they develop in the test cell to replicate real world operations, they can never replicate actual real world scenarios. In airplanes, we are told to take up to above 75% of rated engine horsepower for first 50 hours. (feels like an eternity) It is the scariest 50 hours for the pilot. If we apply that convention to modern, liquid cooled automotive engines, we can probably accomplish the same thing. So for a 350HP Nismo, 75% works out to 263HP. For argument sake, if we develop 350@7500rpm, 263HP would be around 5600RPM. Not too far off 4000. Again, this brings back why Nissan chose 4000. (which work out to about 55%HP) Nice even number and you wont be babying nor destroying in extreme conditions. Just a scenario, I'm not suggesting this is how it's done or actual math etc. Just my aviation scenario theorized for automotive use. BeemaaZ, Magic Bus and Hotrodz like this.

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