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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