I'm a mechanincal engineering graduate, and from the logical end of my mind I can't say I really understand the whole 1200 mile break in thing. I'm going to do it, but here is my thought:

let's say you average 2,500 rpms and 40 miles an hour during that 1,200 miles. That's 30 hours of driving, which means the engine will have revolved 4.5 million times, not including time spent sitting still at parking lights etc. I don't think it would take that many revolutions for the various parts to get worn in completely. It seems the break in period should be set for a time period of engine running and not mileage.

Does this make sense to anyone else? This is of course an attempt to rationalize playing with my G which I've had for only 4 days now

 

I decided to ask this question to one of my former professors as well (this man knows EVERYTHING about cars). If/When he responds, I'll post his answer for those that are interested too.

 

Are you going to be a car designer? Or mech. designer?

 

Actually neither...

I'm going to law school to be a patent attorney. Why do you ask?

 

Well, I have two friends that fight all the time over who really designs cars.

One's a mech. engineer, the others a product designer.
I say the Mech. makes what the artist draws really work.

Thats all!

 

Ah, and yes I would agree with you! The mech engr will be the one who designs the important things, i.e. engine and suspension. A design 'engineer' (I use the term engineer loosely there...) will make the car look good. I'm not sure who would be the one to refine the aerodynamics of the car though, although I have friends who have done some work in that area.

For a second there I thought maybe I had made a calculation mistake and you were going to throw it in my face or something, hehe.

 

there is actually some interesting stuff about break in, and how aircraft engines are done, and other mission critical I.C. engines,

In short, they don't do that sort of break in, they take it through a series specific revs and cool downs....

I can/'t find the link (sorry I suck) but do a search on google)

 

Exactly. And this is the best method by which to break in an engine.

Knowing that many consumers are idiots, the manufacturers aren't going to outline a highly involved process to properly break in an engine for maximum efficiency.

Also, knowing that many consumers are idiots, the manufacturers aren't going to say "Please keep a running total of how long your engine was running, at what average RPMS, calculate the total revolutions that the engine has experienced, and when you hit 28.37 million total engine revolutions, you have now properly broken in your engine."

Plus, miles ARE important because you are also breaking in other moving parts (driveline, suspension, bearings, etc.) not related to engine RPMs.

 

So has anyone gotten the answer on break in??? I am also a mechanical engineer and can't for the life of me understand what 3 million cycles will do that 1 million cycles won't (1,200 miles vs 400 miles). I've also read some links for performance engines suggesting that hard acceleration is needed to properly set the piston rings. I made it past 400 miles without applying any extra throttle, but I'm now at 800 miles and occasionally progressing upwards of 6k rpm.... Anyone have evidence that this is harmful (aside from the maual)?

Mechanical engineers make cars work.

Industrial designers make them pretty. (my $0.02)

 

Go mechanical engineers. Hopefully I'll graduate from UT in the year and a half that I plan on. We deal more with how the car works and not how it looks. Aerodynamics/fluid mechanics included, probably help with the design. Power losses, efficiency, optimization, differential equations all that good stuff. As for break-in I think variability is the key. Varying engine speed and rpms (below 4k) accustom the engine to all the different operating conditions I'm assuming, and the mileage is prolly just a conservative estimate when all the piston rings, seals, etc. are set, not to mention suspension and the other parts of the car. my .02

 

without getting too technical.....i drove my g off the lot like if its any other day.......i didn't redline it nor did i baby it.......did the same for my then new 2k 5sp Maxima.....ok, now back to the technical discussion at hand......

 

alot of perfromance engine builders will tell you that the "break-in" process is crap. One builder used to say that as soon as you have proper oil temp and pressure...you are good to go. For one of his race engine..yes. On a production motor, there may be some "working in" that needs to get done, but probably not 1500 miles worth of it.

 

That's what I like to hear. Like I said - I made it 400 miles or so without really gettin on it.... I can't help myself at this point.... I'm over 900 miles now, so one way or another I'm just about done "breaking it in." Damn, these rides screw.

 

Factor of safety.

The true break in period for a mass produced engine is certainly far less than the recommended mileage. However being an engineering student you'll understand how the ME's designing the engine will pump in a factor of safety for the break in period.

 

On any bike or car I purchase I do the following. It's an in between flogging it and OEM break in.

During all of this, I don't leave the RPM's in anyone spot for longer than a few seconds. Gas, let off, downshift, upshift, whatever you feel comfortable with, I do both.

0-100 miles, I don't exceed 3k RPM's
100-200 miles, I don't exceed 4k RPM's

And so on, until I'm at the rev limiter (in this car 700 miles). And these are slow/steady climbs to the target RPM. Never floor it/punch it. The next 300-700 miles (1000-1500) I take it easy, but go through the RPM range a little quicker, still not flooring it and don't worry about cruising at one particular RPM. At 1500 miles, it's done, drive it like you stole it.

These dyno break in methods are fine for a racebike/racecar, but I don't like them for a production vehicle. The OEM stuff, is for litigation and safety, so obviously some cushion is entered into the equation. Do whatever you are comfortable with, but I'd suggest meeting it someplace in the middle. I've had good success with what I outlined above, in both power (did the dyno runs) and reliability/longevity.