Can I Use 7K Crankshaft To 4K Block?

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October 5, 20169 yr

Can i use that in my 4k block?if can't what should i do to put that crankshaft in my 4k block??

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October 5, 20169 yr

I don't know, but find it unlikely as the 4K stroke is 73mm, while the 7K is 87.

That means it describes a circle 14mm larger in diameter, so take a look inside a 4K and see if there is that distance between the crank and the bottom of the cylinders or the sump. Can it swing past the sides of the block?

Of course it also pulls the piston down an extra 14mm, so they drop out the bottom of the block, and it pushes them 14mm further up, into the head. What sort of piston would have a 14mm shorter distance between the gudgeon pin and the top?? There would be no room for the rings.

It would be a major re-engineering job, if possible at all.

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October 5, 20169 yr

Following on from Altezza, big question is why do you want do it?

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October 9, 20169 yr

Author

Owh like ok2 thanks for your opinion...its means i would to use short conrod if i want to use 7k crankshaft to 4k block.thanks bro and i thinks its so many job re engineering i must do.hmm bro can you give me a conrod spec for the k series engine?i want to know length,sizes bearing n pin?

Edited October 9, 20169 yr by Hamtarohachirokoo

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October 10, 20169 yr

I haven't got conrod dimensions, but remember that if a short conrod doesn't hit the head at TDC because it is short, it will pull the pistons even further out of the cyl at BDC.

In this picture you can see the 20% increase in stroke, both TDC and BDC in red. The piston skirt sticks out the bottom already, as shown in blue, and it will be 20% further out with the 7K crank. I'm not sure if it will stand that. Also, don't forget your piston speed will be much higher, which is why they increase bore rather than stroke.