Prowler V6

[Todd....!!]

Thanks for that insight to the delta 'tween cast and forged cranks in
all of the accompanying apps!

Have learned a lot...

Have learned to use the Fluiddamper for my forged 440 app, will save
it's life, if I hear ya correctly!  As well as the BLOCKS' and Bearings'
lives as well!!

LATER!

Todd...!!


Greg Hermann wrote:
> 
> >    The reason for using a forged crank as compared to a cast one is
> >actually more a matter of "flexability." with a cast crank the material
> >isn't as flexable as the forged counterpart.
> 
> Actually--
> 
> Steel has a significantly high modulus of elasticity than cast iron, both
> in tension and in shear.
> Which means that a steel crank is, in fact, quite a bit STIFFER than a cast
> one. -It does NOT flex as much!-- The steel is, however, much more DUCTILE
> than cast iron, even if compared to so-called "ductile" (or nodular) cast
> iron.  "Ductile" and "brittle" are pretty much antonyms in this context.
> This means that a steel part will deform and "tear" far more than an iron
> one will when it actually fails, even though it takes a much higher level
> of stress to produce a failure in a steel part.
> 
> A steel part also has FAR greater resistance to the initiation of cracks
> when subjected to alternating  tensile and compressive stresses than an
> iron part does. In fact--steel has a well defined "endurance limit" of
> stress under fatigue failure inducing alternating stress conditions, and
> cast iron does not.
> 
> A cast part usually will usually absorb vibrations far better than a steel
> one will--which makes the need for more sophisticated, expensive vibration
> dampers on cast production cranks less pressing than it is on forged steel
> cranks. Witness the fact that if you tap a cast crank with a hammer, it
> gives a clunk sound, while a forged crank will ring like a bell.
> 
> Because a steel crank is actually much stiffer than a cast crank, your
> blocks would probably stand up to significantly more HP if you ran forged
> steel cranks in them---because a stiffer crank would not impose nearly as
> much strain (deflection) onto the bearing webs! (In a case like the block
> failures you are getting, strain (imposed deflection) is the CAUSE of the
> stress, not the other way around!) Of course, you would be wise to run a
> Fluidampr on a forged crank in this application because of a forged crank's
> decreased capacity to damp out (absorb) torsional vibrations compared to a
> cast crank.
> 
> Regards, Greg