What's the typical performance difference between a "green" (brand-new) engine and one that's broken in?

There are many anecdotes that an engine makes more power when it's broken in, and I just encountered what may have been an example. Long story short, over the weekend I slowly reeled in an '07 G Sport with temp plates. My G now has 7k+ miles on it.

Now obviously, many possible reasons for why that happened, but is there typically a power advantage over time? The technical reasons as I understand it is bearings smoothing out, rings seating, exhaust opening up etc. - but have no idea about the actual difference.

Does anyone have any ideas on percentage? Think it was R&T that ran 5.4 0-60 with a brand new G, and they expected a few tenths quicker after it was broken in. So...?

 

Maybe the new car was still under break-in and not exceeding 4K rpms ???

I know that I'm still in that phase and I try real hard not to go over 4k.

Typical cars gain a few tenths of a second on 1/4 mile - but that is much later in the engine's life (something like 30K+)

Yours is practically brand new at 7k miles - shouldn't be a big difference between a new engine (say <100 mi) and yours really. (except for the 4k limit !!!)

 

LOL - I didn't pull away by 20 car lengths! No, I know he was winding it up because his shift points were similar to mine.

 

Breakin by keeping it under 4K is a load of garbage. Check out:

http://www.mototuneusa.com/break_in_secrets.htm
or
http://www.enginesonly.com/break-in.html

or any of many other web sites discussing engine break in.

Regarding green engine performance, I ran my new X on a number of 0-60 runs using a GTech and averaged 5.39s using best launch I could (powerbraking to 2k or so), so I think the R&T number is good for a new car. C&D often shows improvement in 0-60 after extended use, sometimes as large as 0.7s (although I do not personally believe this). This is because of the reasons you stated, and drive train breakin, and tires that are not brand new. Also in some cases cars that have adaptive transmissions will shift more agressively after a long period of agressive driving. I also suspect that the cars come tuned from the factory with basic tuning to allow for a wide range of fuels, and operation over time with high octane fuel improves the engine tuning.


Just for comparison from C&D:

New 40,000 miles
RX-8 6.6 s 5.9s
XJR 4.8 s 4.7 s
EvoVIII 5.0s 5.1s
Mini S 7.4 s 6.9s
Z4 3.0i 6.0s 5.6s

From teh above examples there has been everything from a 0.7s improvement to a 0.1s loss in speed. Average seems to be about 0.4s to 0.5s.

I would not be surprised to see a G in the 5.0 s to 5.1 s area after it has some miles on it

 

To each his own ... I'd much rather follow what the manufacturer says in the Owner's manual than a webpage

Plus engine is not the only component that's "new" during the break-in - all of the other drivetrain components need to be broken in as well.

And since I have stick, I don't have to worry about the tranny learning my habits during break-in I only have to worry about myself learning something and later having to undo it

 

Power braking makes me sad

 

I dunno... this guy looks real smart...

 

I am sure this "moto-man" goofball knows a lot more than the Infiniti engineers who designed the f***ing car .

 

Just as sure as I am that the guy who designs engines for Infiniti/Nissan is not writing f***ing manuals. Get a clue guys, the manuals are written by marketing, media relations and legal. Their biggest concern is that you do not show up at the dealership for any reason for service and that they have no liabilities for anything they write. They could care less if the car does not perform as well as it should, and have no interest in the car lasting beyond your payments, just beyond their warranty period.

But to each their own, I actually think it makes not a bit of difference how you break the engine and drive train in as long as you do not flog it cold. And what the heck, why learn about a subject and make an informed judgement when you can just do what you told in a manual?