I finally have to add something here on the crankshaft business. I finally
got a stock crank to last and last and last. I used it for the final two
years of my contracts with BL. I used a rev limit of 7500 as the 8000 engine
was just too peaky and unraceable.
Okay, how did this happen?
I figured that the only way to fix this problem was to change the place where
the harmonic fell in the rev range while racing. Normally there are three
amplitudes where the third goes straight up off the page. The second is the
toughie and falls right at the range you want to run the engine. Everyone
know this. To change this I tried both a much lighter crank, then when this
was a failure, I made a much HEAVIER crank. The crank had all the heavy
pellets that the crank people could place into
the counter weights, then I MADE BRASS PLATES that were attached to the sides
of the counter weights. The ultimate weight was up about 10 pounds (please
don't ask the specific cause I do not remember). The brass plates were very
close to the rods in the end that clearance was plenty close. I then had the
crankshaft balanced and it went for years at really high revs. We tested many
hours on the dyno at over 7500 with this crank and raced it for two years.
The harmonic was raised to way out of the range we ran the engine thus
allowing us to keep it together. The only problem was the first harmonic was
also raised right to 4000 and that was the point generally run on a pace lap.
It took a bit of doing to keep out of that range.
The funny part is when I sold this car to Jim Ray in Texas he mgnifluxed the
crank after few races and found a hairline longitude crack in one of the
throws and so made a lamp out of this crank and then went on to blowing up
engines with a stocker. Had he just called me on the phone I could have told
him that the little hairline crack was surface deep and had been there all
along. Oh well.
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