I read one time that Rolls Royce let their metal parts especially their eng
block weather outside for several years before their final assembly processes.
4-7 if I can recall correctly. wmts
>
> Subject: Re: Cryogenics
>
> The real success or failure of the investment will be on the first rebuild. If
> the cylinders are still very round and the line bore good and no cracks then a
> good investment. If not money for nothing. I have been looking into the same
> subject to see if i can stress relieve aluminum before machining.. I have had
> some billets that machined perfect and others that curled up like a banana
>when
> making a housing for a slide throttle. All the metal was from a US company and
> not a re-pour. Seems the best parts are made out of stock that has been in the
> rack for years either mine or the supplier. A large high volume distributor
> gives me the worst and a small low volume place the best. Metals as
>manufactured
> have a lot of stress in them and removing it is a big deal to hold shape as
>well
> as fatigue strength. As you get rid of the stress in the material parts can
>and
> are made lighter and stronger. I have heard that when Carrillo makes a set of
> rods there are many stress relieving steps between machining operations. I
>also
> suspect that is one of the differences between copies and the original parts.
> The copies are cheap but are all the stress relieving steps taken. Might look
> the same but be completely different parts.
> Dave
>
>
> Rick Byrnes wrote:
> >
> > I have no scientific data that it works but did use cryo on the latest tall
> > deck 2.3Litre block I used for the N/A motor. The virgin block was shipped
> > to OKC and went thru a process of -300 to +300 to ambient in a very
> > controlled cycle. I do not believe that this made the material stronger,
> > but rather provided a good stress reliever of the entire structure. I asked
> > the machinist to pay particular attention to how the metal cuts, chips and
> > curls, after the process. He reported no difference from a normal 2.3L
> > part. The iron was not harder. We didn't measure hardness, but it seemed
> > unimportant at the time. Since the N/A motor has significantly less power
> > than the turbo, the block is not overstressed by any means.
> > Prior to doing this I had some rather lengthily discussions with
> > metallurgists and their consensus was that it should not permanently change
> > the nature of the alloy, but serve as a stress reliever.
> > Did it help? Don't know?
> > Did it hurt? NO!
> > Did I waste my money? Maybe. Maybe not.
> > I do know that Roush has used cryo on engine parts, and they have some
> > people a lot smarter than me.
> > On the other hand, we can all be sucked in by PFM.
> >
> > Regards to all
> > Now back to the garage
> >
> > Rick
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