i know the general consesus on breaking in a rebuild is never above 4 grand, or boost, for 200k miles or untill the compression peaks out.

but what im also wondering, how many operating hours should it need? like ... what if the engine isnt inside a car? would letting it run or idle in my drivewayt for a couple of days suffice? and i mean a couple days as in, let it idle through a whole tank of gas.

 

200k miles?

Did you mean 2,000 miles? Sounds about right.

Letting the engine idle for an hour does not seem like a bad idea, it will do the 'initial' break in that everyone will (probably) agree is needed. I don't think *anyone* would suggest you ever go WOT on an engine that is starting for the first time.

However idling is a bad way to do a full break in, since you need to vary the RPM's. Breaking it in solely on highway miles isin't ideal for the same reason.

 

Break in variables:
condition of the housings (new- less miles, used- more miles, really used- whatever)
Are you switching from 3-piece to 2-piece seals- more miles.
Rotor bearings, New- more miles, or re-used- less.
Brand of seals Mazda, RA, Atkins, Hurley, (I'm not sure which seat in faster)

 

its just a general question. so should i just.. um.. u know.. rev it up from time to time? i dont want to drive the car while its breaking in this is why i ask.

 

Well, you SHOULD drive the car for a break-in, if you want to do it right... Putting load on the motor is necessary for breaking it in.

Of course, a half-an-hour of idle'ing before driving it around is probably recommended. Letting it run for a DAY in your driveway is kind of ridiculous, lol. That would be like the equivelent to an hour of varied load driving IMO.

 

o word? well.. damnit... so your saying i have to drive it. o well... ill drive it in circles then.

 

Varying rpms and loads is what is ideal for break-in.

But a "general" consensus is not always right for YOUR application. What SureShot was leading to was that it all depends on what parts you reused, what parts are new, what brands of the parts or types, etc.

For example, Mazda Factory Race (MFR) rotor bearings that are brand new will take less time to break-in than stock rotor bearings due to the deeper oil groove/increased clearance.

EDIT
However letting it idle is always a good thing! It will help, just not as much as driving. You really need to put MILES on the car with varying rpms. If you feel like leaving it and letting it idle for a while, go for it. But don't think it's a replacement for driving miles.

Also, there are some people out there that will disagree with all of this and say that after 30-60 minutes of idle time it's good to go at all revs. And of course people do this, and some turn out okay. It's just not advised by everyone, including Mazda when the car was brand new.