What's the correct way to break-in an engine?

[BATMANs]

From what I have learned and read is that you take it easy on the engine and vary the RPMs. City driving is the best.

But I'm wondering if anyone has heard that running the engine hard is the best way to break it in.

http://www.mototuneusa.com/break_in_secrets.htm

These Honda F3 pistons show the difference.

Although these pistons came out of engines which were raced for a full season, they weren't set-up with any special clearances or other preparation.

These engines were never worked on prior to being raced. They were totally stock as built by Honda.

The only difference was the break in method they used...

The one on the right was broken in as per MotoMan's instructions.

The one on the left was broken in exactly according to the owner's manual. The resulting leaky rings have allowed pressure to "blow by" down into the crankcase on acceleration, and oil to "suck-up" into the combustion chamber on deceleration.

 

[colslaw87]

Pretty interesting read.

From what I read, doing WOT runs (when engine is warm) will seal the rings and prevent leakage. I wonder if there is any other information on this

 

[BATMANs]

So in theory rental cars and test cars at the dealers may have been broken-in in the aforementioned manner than the owner's manual.

 

[clr1024]

So in theory rental cars and test cars at the dealers may have been broken-in in the aforementioned manner than the owner's manual.

LOL - that's one way to look at it:biggrin:

 

[BATMANs]

LOL - that's one way to look at it:biggrin:

that explains why 3 of my friends that bought rental cars are not having problems with the engine (ie- blue smoke, etc.)

 

[lithiumus]

Its a good read and makes a lot of sense. It's not just running them hard, it's doing progressively harder runs in a controlled manner along with proper cool down and warm up.

I'll be doing this with my new car. The problem really is making sure that you have a good stretch of road to do second or possibly 3rd gear pulls to ensure you have sufficient load on the engine in the latter runs.

I did read in the FAQ that the NSX engine did not like to be run over 6k at the testing grounds in Togichi so that may be some contradicting info but there are no details around this...

 

[BATMANs]

.....I'll be doing this with my new car. The problem really is making sure that you have a good stretch of road to do second or possibly 3rd gear pulls to ensure you have sufficient load on the engine in the latter runs.

I did read in the FAQ that the NSX engine did not like to be run over 6k at the testing grounds in Togichi so that may be some contradicting info but there are no details around this...

The car that I will be breaking - in the motor will make 2nd- and 3rd gear useless. Just nothing but tire spin.

Tell me more about the NSX and 6k rpms.....

 

[vmlinsx]

My pop used to build engines, and he always stressed proper warm-up and cool-down cycles, and good hard pullls with the engine at proper operating temperature. The warm-up and cool-down cycles are important for a bonding layer of oil to form on surface of the metal. This bonding layer will reduce metal-metal contact and reduce friction. The repeated warm/cool cycles help this layer build up on metal surfaces. Giving the engine loaded pulls to redline once it has reached proper temp helps seats the rings. He also said avoid lugging the engine during break-in. He'd change the oil a few times during break-in, like after the first hour, and at 20 and 100 miles with natural oils. After break-in, he'd switch to a synthetic.

 

[angus]

It is true , you need to run it hard to seat the rings , this is also outlined in the instructions that come with some piston ring sets. You need to accelerate and decelerate back to back until the rings seat , you only have a certain window of opportunity to do this.

Here:

http://www.hastingsmfg.com/ServiceTips/breakin_procedure.htm

 

[nsx2tall]

Having just broken in an engine [not NSX] last year, my opinion is for you to follow the advice given to you by your engine builder and no one else. There are enough contradictory opinions out there that I don't trust any of them other than from the guy on the hook for giving you a new engine if the first one gets f-ed up. If he says drive it hard then drive it hard. If he says drive 1200 miles like grandma, then grandma you should be.

 

[BATMANs]

Having just broken in an engine [not NSX] last year, my opinion is for you to follow the advice given to you by your engine builder and no one else. There are enough contradictory opinions out there that I don't trust any of them other than from the guy on the hook for giving you a new engine if the first one gets f-ed up. If he says drive it hard then drive it hard. If he says drive 1200 miles like grandma, then grandma you should be.

valid point, however, since my engine has all sorts of power mods like a Supercharger, it's likely that if anything happens to the engine the finger will point to the mods.

The old method of breaking in an engine may not show an adverse side effects that are acute in nature.

In other words, it may be a difference of the oil being slightly dirtier, I'm losing 20HP from a 700HP engine, and/or I'm consuming 1 quart of oil every 5k miles instead of 10k miles.

 

[4AU4LIFE]

I hope this turns into a very informative thread.
~6 yrs ago I had my engine rebuilt using all OEM parts with the exception of the pistons which are JE.
I drive my car very conservatively. I have put ~25k miles on it since the rebuild and it appears that my oil consumption is the result of leaking valve stem seals. The engine runs fine but after it is up to operating temps and the accelerator is pushed, I do get some puffs of blue smoke. The car seems to really drink oil but doesn't leak a drop on the ground.
Compression test done comes back with perfect #'s for all cylinders. Haven't done a leak down test yet but I have a pretty good idea that it is the seals that need replacing.
So, it looks like when I go to have the TB/WP maintenance done, that I'll get them to do the seals also. I'll have the test done first to make sure that those are needing replacing before doing it.

 

[nsx2tall]

I hesitate to offer conflicting or non-NSX related advice, but for reference here is the new engine break-in procedure that I followed:

http://www.raw1performance.com/index_files/Page1229.html

 

[gsrboy]

I started up the engine check for leaks, and its towed to the tuner. I broke it in the hard way, but after the 2nd pull no more blue smoke. The rings sealed nice and the compression test was perfect. 20k+ miles now and my friend has it. No issues at all.

I used http://www.mototuneusa.com/break_in_secrets.htm as the reference.

 

[DocL]

Guys, one thing to remember here is are you breaking in the engine of a brand new car, or just a new engine.

If it's a brand new car, there are other things that need to be worn in slowly and that is why the manufacturers recommend a 500-1000 mile break in period. Most casual car buyers don't realize that the tires need 500 miles to get scrubbed in and the brakes need about the same to get bedded correctly. Most engines are good to go out of the box, however a high performance engine does need a protocol to be followed. However, to most of us educated drivers, we know how to bed pads and heat cycle tires correctly. I'd say that 90% of the masses don't.

 

[angus]

I started up the engine check for leaks, and its towed to the tuner. I broke it in the hard way, but after the 2nd pull no more blue smoke. The rings sealed nice and the compression test was perfect. 20k+ miles now and my friend has it. No issues at all.

I used http://www.mototuneusa.com/break_in_secrets.htm as the reference.

I agree with what this says , if you read , it actually says what I said , almost word for word:

There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!