At 06:08 AM 08/26/2004 -0500, Jack W. Drews wrote:
>Okay, how many drivers WHO LIMIT THEIR RPM's to 6000 have experienced a
>broken crank? How many have experienced a broken rod? We know how many
>folks are on the FOT list -- the math will be pretty easy.
Jack, I am assuming you are looking for data on STOCK cranks, not billet
cranks. I am concerned about the couple of broken Moldex's I have heard of
recently. I would love to hear the details of their demise, and see if
there is a pattern. Yes, I run a Moldex with Carillos, and turn 7K on race
day. (knocking on wood)
I broke a stock crank at the end of 2001. It broke behind #4, the typical
place. The crank was turned .010 under, radiused, balanced, nitrided. It
was running stock prepped rods, one of BF&E's first generation harmonic
balancers, and a lightened stock flywheel. The crank work and the rotating
mass balance job was done by my very good local machine shop. I TRIED
(really, I did!) to limit my RPM's to 6K, but truth be told I came in from
several race sessions with my tach telltale reading 6200 or better.
Not to throw another variable into this, but I believe tachometer error
plays a big part of this. Racers running stock tachs are really at a
disadvantage. Sure, they look right in the dash, but the negatives are
overwhelming, in my opinion.
Not reading actual engine RPM. I believe the typical failure mode is they
read higher than engine is turning. OK, that is not a bad thing for keeping
engines together, but effects lap times. If the error is the other way, you
might think you are turning safe RPM's, when in fact you are not.
Electronic tachs pretty much tell the story the same over time.
Engines with lightened flywheels spool up faster than the stock tach needle
will react.
No telltale. Especially fun to see what you wound it up to when you missed
that shift!
Cheers
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