I don't have drag racing experience with inlines but I did do a few years with Limited Class Hydros with inlines as well as bent motors. Although I have 250s in two of my cars, I've never built a Chevy 6 to race, but I have broken crankshafts in the race boats.
In the PNW we've always tried to have big fat race courses where we were able to keep our engines wound up. As a single heat would be 5 miles and the engine required to run 3+minutes @WOT in a good handling boat, we couldn't build our engines like one would for the strip. The first engine I used was the 144" Falcon. Injected on methanol, the 4 main bearing motor would break frequesntly in the bottom end. We had to safety wire everything on the motor or attached to it, because the harmonics unbolted everything. I made 175-180hp and got about 30-40 minutes of 7-7200rpm before suffering severe pan failure. I switched to Nissan 2.4, same fuel and induction, 235-240hp. I redlined it @7500 the first year and got a full season, but the next year turning 78-8000 I unwound two bottom end$. I've always felt that harmonics at high rpm was the real killer in the L6s. CNC Dude's experience of 20 runs, approximately 3 minutes of full throttle, shows what happens when you really turn'm up.
