Drag Illustrated Issue 139, December 2018 | Page 74
DI TECH
to a keyway. Not cutting as deeply into the post also
maintains its strength and integrity better directly
where it is needed on the post. And the flip side of
that is not losing the material that is machined out
for the depth of the keyway. In fact, the post on a
splined crankshaft is bigger than those without
splines. So along with being stronger in design, the
added post material provides even more strength
over using the key method.
In effect, the bonus to using a splined crank-
shaft is threefold. One is using the surface area to
disperse the load of the blower drive pulley. Two,
a stronger post to also support that critical load
point. And three, the weight of the crankshaft
(and resulting rotating mass) is kept to a mini-
mum while strength is not compromised. And
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any help the post gets in being stronger and living
longer translates to the crankshaft doing the same.
All these factors combine so the spline will out-
live the crankshaft in these typical bigger blower
applications. That’s because in the example of a
Top Fuel engine, the crankshaft will be removed
from service due to torsional fatigue before the
splines show cause for concern.
What little differences there are between
splined and non-splined crankshafts comes down
to only the post itself. For one, the post diameter
is increased .175 inch for the equivalent of the
big-block Mopar, the standard size in those bigger
blower configurations. Crankshafts with splined
posts require using specific accessory components
that vary by application. These would be the
pulleys used on the crankshafts, insuring mat-
ing splines and sizes are used. It’s more about
matching the blower drive components to the
spline and vice versa.
Nothing else changes when using a splined
crankshaft. The crank timing gear is still installed
and removed the normal way. The balancer also
is installed/removed the usual way. The same
timing chain covers are still applicable.
Staying ahead of weak links, all Callies splined
post crankshafts are manufactured from billet
steel. Splines are not found on forged cranks, as
forgings don’t have sufficient material on the front
end and post where splines are machined. Cal-
lies uses 100 percent quality-certified American
steel on their Ultra Billet splined crankshafts,
available in a variety of strokes. Using the billet
option also allows the opportunity to select from
a wider variety of materials, further fine tuning
each engine’s application.
Using a splined crankshaft also allows racers
to “strengthen’ their engines even if they aren’t
running the higher volume superchargers. This
can add reliability and product longevity to their
engines. In short, if you can run an engine com-
petitively with less stress, stronger parts and as-
semblies should last longer.
Down the line, as engines not using the higher
volume superchargers evolve, they, too, may need
the safety and reliability of a splined crankshaft.
For engine shops, it will be an easy upsell. Include a
stronger, splined crank in a build and a racer won’t
need to worry about a shorter life of their crank
due to the pulley connection. Most racers will buy
into stronger and longer wearing in a heartbeat
and those on the edge of needing a splined drive
will smartly make the jump. - BY JOHN CAROLLO
Issue 139