Re: fractured rods

[bearbvd@domain.elided (Greg Hermann)]

>Since I don't have all parties direct e-mail- to the digest it is....
>
>One thing that might help understand how this is done is that our (Ford)
>fractured con rods start their life as powder metal.  I would imagive that
>it is easy to custom the mold, besides the notch, to make it fracture
>at the correct point.  And, as explained, the load it entirely taken by the
>bolts.
>
>You know, a problem that nobody has brought up is that when the rods are
>fractured, they have to fracture right away, and not have ANY ductile
>movement- or this whole exersize was pointless.
>
>agreeing that this is an interesting subject
>
>Eric Storhok
>Ann Arbor, MI

I have read some details about these rods--a fascinating production
technology indeed. I would be interested in seeing ALL of the testing data
on rods built this way, with particular emphasis on fatigue testing  and
Charpy impact testing results--but I rather doubt that such data will be
forthcoming for quite some time, if ever.

It may well be that I am wrong in my engineering instincts, but, until I am
convinced otherwise by hard data, I will stick with forged or billet rods,
made from either 4340E  steel or, even better, a maraging steel, with
either one properly heat treated, polished, and shot-peened, and with top
quality cap screw bolts and tubular dowels for cap  alignment and retention
in any high performance engines which I build.

Quite simply--it seems VERY inappropriate, to me, to use a non-ductile
material for a connecting rod, and I am inclined to regard this "advance"
with the same kind of skepticism which I had for the Chevy Vega's
(aluminium bore surface) engine block!

Stated another way--I see plenty of reasons why these rods are cheaper to
build, but very few reasons why they are better to use in a real world
engine!

But--NO, I will not volunteer to eat one if my feelings are incorrect!

Regards, Greg

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