3.79 Stroke CRanks

I'm real curious as to how a 3.79 stroke 4.030 bore engine will make more hp then a 4.00 x 4.030 assuming that good flowing heads (300 cfm+) are used on both (Indy, W-2, W-9, Brodix, etc.), and the cam is set up for the hp peak to come on at the same rpm and reciprocating weight was kept the same. Someone please enlighten me what the theory is behind this. I'm ready to learn something new today!

I know someone here on this forum that broke their cast crank running 540-550 hp. He did a LOT of racing though. I'm not saying that a cast crank won't handle 550 hp, I'm just saying that I don't know for how long. Put a 150-200 shot on top of that and you got a grenade. Neither the block nor a cast crank can handle that kind of abuse, not to mention the SIR rods. it's all about fatigue resistance. Think of a paper clip. You can bend it so many times until it breaks. I beam Rods under this kind of hp bend minutely and eventually, they just can't take it any more. That's why H-beams are designed the way they are, with two flat planes perpendicular to the crank to resist any bending under higher hp loads in an attempt to mitigate fatigue failure.

Jim Szilagyi (the engineer for Mopar Performance) says that the upper limit for a stock block (assuming it sonic checks out) is 500 hp. I think that with proper set up and machining that limit can be pushed up to 550, maybe a bit more with aluminum rods, internal balancing, superlight pistons etc. With nitrous on top of all that, I would definitely use a MP racing block.

Mr Szilagyi also says that cast cranks are good to 500 hp and no more than 6,000 rpm in a stroker application. Can that number be exceeded? Yes, but for how long? Cast cranks reach their limit and start to crack, those minute cracks propagate over time then the crank snaps, forged cranks reach their limit then start to bend which resists cracking.

The big question is, a motor dropping a bottom end is not a pretty sight. Not only is it expensive, but what about the guy in the other lane when the bottom end lets loose at 125+ mph and oils the tires? What about the spectators? I know I don't want to explain to his wife and kids that I killed their husband and daddy just to prove a point and be cheap (assuming I'm still alive).

I personally, (and this is of course, my opinion, and we all know about opinions! lol!) will pay the money for a forged crank and racing block if I'm exceeding 500 - 550 hp for my, the other competitor and the spectators safety.

I hope I'm not stepping on anyone's toes here, and I don't want to sound like I'm preaching, but I've seen the ambulance out on the track more than once and it's not good for anyone involved.