Breaking in (ok, running in for the Brits)

I don't really want to bring back this argument, but I have new information after talking to an acquaintance who used to build top fuel motors (I mean engines, engines...this site is really having an effect on me) and now does fuel system development. He is the most knowledgeable person I have ever talked to about engines.

Anyway...I asked him why the owners manual called for no full throttle, and lower rpm, and what was the real deal for breaking an engine in. He said (obviously trying to make this simple enough for me to understand) that since the engines were already load tested, the important part of breaking in was to not overheat any parts of the engine, especially the piston rings, which would loose their 'elasticity' if they got too hot. This means to keep the rpm's down, but even more importantly, to be on and off the throttle while in gear. I assume this is what is meant by 'vary vehicle and engine speed.' When you are running at constant speed (cruise control) or accelerating, the piston rings get hot. On a newer engine you want to keep them cooler. When you get off the throttle and leave it in gear, oil is splashed all over the cylinder walls (something about vacuum pressure) anyway, this cools the rings. So, long story short, make sure you accelerating and decelerating, and leaving the car in gear while you decelerate.

-Andrew

sorry about it being so long

[retroom]

Quote:

Originally posted by obehave
Yea! Somebody knowledgeable that backs up what I've been doing forever. Vindication

Fine when breaking in an engine. Doesn't it make you car sick driving that way all the time?

retroom

[EBMCS03]

Good information to know... Thanks!!

[JCIP]

Very good to know L8 Apex! I have just 250 miles on the clock, and I have been hearing about the 'run em hard if you want em fast' theory. I like the sound of your engine man's advice! I think I will do as he suggests! Sorry, got to motor...
Thanks!
JCIP