Originally Posted by 5AcresAndAFool
Yes I know it really doesn't matter, but when breaking in a new engine is heat cycling engine important? Is it just better to break it in with as few thermal cycles as possible, varying rpm, varying load, ect.
I was always under the impression that heat cycling when breaking in was beneficial. Thoughts?
In general terms it is and is not and this comes from the full spectrum of designing machines through commissioning then eventually a reman.
First a "break in" has to be defined.
Most people define it is where various surface finishes, tolerances and components "wear to mate" and settle in in terms of displacement, alignment and so forth. ( and any combination of the above)
Theres the school that says you need to break in everything- they are 100% correct
Theres the school that says if its "built right" theres no need for an "official" break in- they are also 100% correct
The truth lies in-between and rests on 2 specific things
The quality of that rebuild ( for the purpose of this answer lets agree to assume the quality is correct because otherwise its an infinite set of "what ifs")
The other thing is the physical properties of the machine ( what we call the service factor in industry) such as shaft deflections, thermal growth, internal stress distribution of the housings and a host of other things machine specific. These create unique wearing scenarios and stresses unique to that specific machine that cant be effectively modeled or anticipated.
So even with the "perfect rebuild" and 10 qts. of uncle bobs unicorn oil there is that 3rd element that has a significant contribution to "settling in" ( total scope of the effect is machine specific) and machine wear.
So, yes they are important in the general- how much and how many cycles is usually either experience or T&E.