Maybe the frequency of a steel forged crank is different than a junk cast one.
Back in the day Headrick said he would only get 12-14 runs on a cast crank.
Since I run a turbo I don't need to turn much over 6000 RPM.
We actually changed the cranks out every 20 passes because that's the most runs we ever got out of one before they broke. So Jim decided that at twenty passes, we would change cranks regardless.
It didn't matter if they were steel or not, Jim used them at first, but they still never lasted as long as the cast cranks. The steel cranks were always more expensive to buy, so Jim didn't see the need to spend extra money for a crank that wasn't going to last any longer than a cast one.
The reason they only lasted for only twenty passes was that Cotton would leave the starting line at between 10,500 and 11,200 RPM, that coupled with dropping the clutch in a 3240 lb car was very abusive to the cranks and other parts. Once they switched to Comp Eliminator and the rear engine dragster, the launch RPM was at a more sane 5500 to 6000 RPM, and the cast cranks lasted indefinately then.
