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which block would be stronger for a 500in stroker turbo build and would aluminum main caps and main stud girdle be stronger than four bolt caps and main stud girdle

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The 400 block, that sonic tests well, is a lot better choice for a stroker build What amount of power and how much life do you want out of this build? If your going to use a power adder of any sort to start with and want to make over 800 HP, start with a good race block now instead of trying to bandaid and patch up a stock block As far as adding bottom end strength to a Mopar wedge block like the 361/440 blocks a good set of steel or aluminum main caps and main studs will help a bunch, the stock caps with bolts will crack and fail, if you abuse and push it far enough I don't like the four bolt main cap coversions at all They require drilling through the stock main webbing removing one of the designed in strengths of those block Same thing on a bolt in girdle, using the oil pan bolts and main studs only adds longitudintional(SP?) stabilty, no strength added that I can see to the main webbing

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I have a Megablock, and had some cap walk despite four bolt mains. I bought a center counter weighted crank, and the problem went away. That tells me those center counter weights are worth a lot of stress reduction. Look at some of the high powered motors out there that now run center counter weights stock. Ford saw fit to equip some of its top performers, knowing that guys like us will put blowers on them and turn the wick way up. I don't understand why more engine builders don't promote these. It is pretty simple. If you are balancing the center rods and pistons on counter weights that are not directly under them, you get rid of vibrations, but the stress of those imbalance loads has to travel through the block! So guess what happens next. The main webbing in the block lets go. If the stress were evened out, I bet a stock block would take a lot more punishment. The cranks won't flex as much, and live longer also. If you are set on using a stock block, then the center weighted crank is what I would use.
The stock block will still be a limiting factor though. It doesn't have the thick cylinders or the robust bottom end of a KB for instance. For a very high power application, then to me it only makes sense to use both the center weights, and an aftermarket block. Then crank up the boost!!

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