Elmo P. Shagnasty wrote:
> In article >,
> "motsco_ _" <"motsco_ > wrote:
>
>
>>At least one of your questions is answered here . .
>>
>>http://www.mototuneusa.com/break_in_secrets.htm
>>
>>I'm not sure if I agree with everything said, but it's starting to make
>>sense to me. . .
>
>
> I like the guy's short answer: "The Short Answer: Run it Hard !"
>
> According to the Corvette engineers, he's 100% correct.
>
maybe that's why g.m. are in such trouble?

the break-in achieves two things:

1. the cylinder walls have to glaze.

2. the journal bearings have to seat properly.

running hard from new prevents both. if no glaze forms, oil consumption
remains high as sealing is less complete and the wear rate remains high
because the glaze is harder than the metal substrate [irrelevant for
racing engines, but not for consumer road vehicles]. if journal
bearings are run hard before they've seated themselves, you can have
patches where there is little or no hydrodynamic film and metal on
metal. as the journals are such soft metal, they can quickly get ripped
and suddenly, you have a rebuild & regrind on your hands.

there /is/ validity in not running /too/ slow as that can create
excessive carbon buildup, and the journals seat fairly quickly with the
high-precison build we generaly have today, but confusing the potential
for a quicker break-in with the ability to run hard from new is somewhat
misplaced.