[Cliff R]

Good information. The "weak" link here when going to 3" mains is the construction of the crankshaft. We've seen enough cast steel Eagle cranks fail to avoid them in 3" or 3.25" mains. One of our customers in particular, broke one in 4 peices at 730hp, and another one in two peices about a year later. He finally went to forgings, no more troubles. One of the cast steel cranks was raced for two seasons, nearly every weekend, in the high 9's/low 10's, then, without warning it gave up, windowed the block and oiled down the entire top end of the track. About a year later, the back-up engine did the same thing.

The 3" main cast steel cranks have their limitations, as we've seen them in 500hp engines last for many years without problems.

FWIW, with the forgings currently available, I wouldn't even look at a cast crank at any power level.

As far as rpm potential, I don't see the larger main 3.25" journals as a big trouble area here. If you are building from scratch, you should be looking at 3" main blocks. Easier to obtain, and plenty of good cranks readily available in just about any stroke you would want to set them up with.....Cliff