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Stroker crank is it 5140 steel?


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Why not measure its mass, submerge it in some sort of liquid and see how much volume it displaces, and then calculate what the mass of a cubic centimeter of material is.


Assume it's uniform density. Calculate the volume of material that will be removed if you gun drill it (obviously just volume of a cylinder). Total mass - mass of material removed = new mass?


I'm not sure if it is proper or not to assume uniform density. I figure not, but it gets you in the ball park for sure.




Or I mean, I guess someone could just give OP a real answer. :bonk:

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John, I had read somewhere that these cranks shouldn't be lightened IF they are in sustained high RPM's, lets say 7000 and up due to harmonics. Since gun drilling is on the axis of rotation, removing weight from that location wouldn't be harmful like removing material from the counterweights would?


Then again, I suspect gun drilling a crank would weaken the last rear main bearing where the crank snaps sometimes.



I'm all curious now.

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  • 2 weeks later...

What benefit do you see in this process?


As mentioned, you will be removing mass from the very center of the crank, so that should have no effect on how rapidly it spins up.


And you surely are not doing this to lighten the car.


You are proposing to remove metal from what is the very heart of the engine?

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In terms of fair market value (as opposed to trades or DIY) is this more, or less, than $2,000 in crank work?


Absolutely beautiful. Do want.


I don't know how much was spent specifically on the crank. I paid for a whole engine. I do know that it took two LD28 cranks to get one that stayed straight enough after Nitriding to be of use. The first one bowed and later sonic inspection found some porosity inside the number 3 main.

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