Build on "the competition",......

clementine said

I admittedly am still learning but when I was building a nitrous motor it was explained to me that you are basically putting a lot of force on the crank pushing it out the bottom of the motor. Boost would be doing the same thing no? Not sure if you are saying why I would question a renowned builder or if you are agreeing. Im just a guy listening to what the guy said. He brought attention to the fact that they were choosing a motor that had fewer mains. RRR said it was no big deal. I believe you are saying the same. Great, its no big deal. Logically to me...Id probably go for more mains. Shed some light on me and explain how fewer mains is no big deal when dealing with those type of power levels. Im open to it.

Click to expand...

There are a number of parameters in play here. First up, V8s only have 5 mains, so there are more mains/cyl in a 4-main 6cyl. If the main dia & rod jornal dia are sized right, there is overlap & rigidity, but there is more friction. There is more room for wider, heavier, & thus stronger throws for a given alloy/mfr.....but it is much heavier, & needs to be. If quick rev response up & down is the goal, lighter is better, not a real problem for a turbo'd mill primarily aimed at the drag-times & pulling. There's also the inline evil of crank twist because of the shaft length, here the amount of mains can reduce off-axis deflection when there is enough load or the onset of detonation, but there is also a less forgiving/shorter stress path w/7 mains. In other words, it may not deflect, but may break....sort of like forged vs cast, stronger will flex more vs less strength more rigid...most of those old forged cranks were overkill, to their detriment, as long as the block & mains can handle the load they're good. The center cap work on those old blocks is enough to take a bunch.....hope that made some sense....