Breaking in new "rebuilt" engine
11-29-2003, 02:27 AM
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Breaking in new "rebuilt" engine
Hi guys, this is my first post in this forum.
Well I'm trying to do some research on how to properly break in a new engine. It's a very controvertial topic and many different opinions are given.
I wanted to hear from you guys what you think about it.
Basically there are 2 schools of thought. The first is to take it easy for the first little while which means no hard full throttle runs for the first 500mile or so. Keep the RPMs low. After that you can start to open it up.
The second school of thought is to immediately put some hard loads on the engine right from the start. Perhaps you have seen this article, http://www.mototuneusa.com/break_in_secrets.htm
It says that the break in period occurs in the first 20 miles! If left too late the piston rings will never form a nice seal.
Any opinions on the matter is very much appreciated. Thanks!
Well I'm trying to do some research on how to properly break in a new engine. It's a very controvertial topic and many different opinions are given.
I wanted to hear from you guys what you think about it.
Basically there are 2 schools of thought. The first is to take it easy for the first little while which means no hard full throttle runs for the first 500mile or so. Keep the RPMs low. After that you can start to open it up.
The second school of thought is to immediately put some hard loads on the engine right from the start. Perhaps you have seen this article, http://www.mototuneusa.com/break_in_secrets.htm
It says that the break in period occurs in the first 20 miles! If left too late the piston rings will never form a nice seal.
Any opinions on the matter is very much appreciated. Thanks!
11-30-2003, 04:27 AM
#2
RL Technical Advisor
Zarman:
Everyone has an opinion on this subject, but I'd offer mine as I've been doing this sort of thing for many many years,....
New engines are comprised of LOTS of new parts that do not fit each other precisely,.....yet. The main goal during the break-in period is to assist all these parts to conform to each other while containing the heat and friction associated with the process.
For street engines with a long-life expectancy, I am gentle to the engine in its first 1000 miles and do not exceed 5000 RPM. I change the oil at 500 miles and 1000 miles before I begin the normal oil change regime.
The key thing is to never get the engine hot during this time by overrevving or by lugging. To assist the rings in seating, one should not operate the engine at constant RPM's for periods of time; one should be accelerating and coasting down again most of the time during the first 3000 miles so that the rings will seat properly. You'll know that this has occurred as oil consumption will stabilize.
Ring seating is aided by part-to-full throttle acceleration from 2500 to 4500 RPM in the higher gears. When the throttle is opened up at low RPM, the rings are forced outward by gas pressure against the cylinder wall and will burnish themselves and conform very precisely to that surface. When you back off the throttle at higher RPM, oil is drawn up, the rings relax tension against the walls and cools the rings and cylinder walls off.
Repeating this process is what is important during break-in so that engine develops best compression & ring sealing.
This has always worked very well for me when someone expects the engine to go another 100K+ miles.
Now,....Race engines must perform at peak HP immediately with little regard for long-term life, therefore these are broken-in on the engine dyno for 8 hours of running and then installed into the racecar for immediate use.
Hope this helps,
Everyone has an opinion on this subject, but I'd offer mine as I've been doing this sort of thing for many many years,....
New engines are comprised of LOTS of new parts that do not fit each other precisely,.....yet. The main goal during the break-in period is to assist all these parts to conform to each other while containing the heat and friction associated with the process.
For street engines with a long-life expectancy, I am gentle to the engine in its first 1000 miles and do not exceed 5000 RPM. I change the oil at 500 miles and 1000 miles before I begin the normal oil change regime.
The key thing is to never get the engine hot during this time by overrevving or by lugging. To assist the rings in seating, one should not operate the engine at constant RPM's for periods of time; one should be accelerating and coasting down again most of the time during the first 3000 miles so that the rings will seat properly. You'll know that this has occurred as oil consumption will stabilize.
Ring seating is aided by part-to-full throttle acceleration from 2500 to 4500 RPM in the higher gears. When the throttle is opened up at low RPM, the rings are forced outward by gas pressure against the cylinder wall and will burnish themselves and conform very precisely to that surface. When you back off the throttle at higher RPM, oil is drawn up, the rings relax tension against the walls and cools the rings and cylinder walls off.
Repeating this process is what is important during break-in so that engine develops best compression & ring sealing.
This has always worked very well for me when someone expects the engine to go another 100K+ miles.
Now,....Race engines must perform at peak HP immediately with little regard for long-term life, therefore these are broken-in on the engine dyno for 8 hours of running and then installed into the racecar for immediate use.
Hope this helps,
11-30-2003, 11:28 AM
#3
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Having broken headstuds changed out right now, while motor is open new valve guides,rings and bearings going in. When I asked wrench what break in procedure to follow he said "drive, its good to go right out of the box". now i'm scared
Tom
Tom
12-03-2003, 05:07 PM
#7
RL Technical Advisor
I cannot speak for anyone else, but when we start a new engine & seat the rings on our engine dyno, the loads and RPM's vary widely for 8 hours before we do any power pulls.
Last edited by Steve Weiner-Rennsport Systems; 12-03-2003 at 10:43 PM.
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12-03-2003, 05:45 PM
#8
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So when breaking in an engine "in the car" is it best to accelerate gently for the first 500miles (ie equivalent of 8hrs at ~63mph)? And not overload the engine.
12-03-2003, 10:46 PM
#10
RL Technical Advisor
Hi David:
I always oil the rings with regular motor oil,.....never, ever dry,....
D:
I'm just nice to it during the first 500 miles and do not take the RPM over 4500. Above all, do not get it hot!
I always oil the rings with regular motor oil,.....never, ever dry,....
D:
I'm just nice to it during the first 500 miles and do not take the RPM over 4500. Above all, do not get it hot!
12-10-2003, 02:37 AM
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Steve,
Can you elaborate on the process of oiling the rings? On the first engine I rebuilt I oiled the cylinders and rings, (lightly) and the rings never actually seated. On the next engine I oiled the rings, on the thickness only, and seating was not a problem. So, on the 3rd engine I oiled the rings, cylinders dry, and just a drop on the piston skirts to aid in sliding the cylinders on, seating seems to be fine. Is this the correct method?
Thanks for your input !
Can you elaborate on the process of oiling the rings? On the first engine I rebuilt I oiled the cylinders and rings, (lightly) and the rings never actually seated. On the next engine I oiled the rings, on the thickness only, and seating was not a problem. So, on the 3rd engine I oiled the rings, cylinders dry, and just a drop on the piston skirts to aid in sliding the cylinders on, seating seems to be fine. Is this the correct method?
Thanks for your input !
