I have an evo 7 motor that needs a rebuild. Spun a bearing and knocked pretty bad. I also have an evo 4 motor laying around with a good crank. Would I be able to use that crank on the evo 7 motor or is it weaker ?

 

It depends on how bad the damage is. In some cases the journal on the crank can be ground and repolished. You would just use an oversized bearing to support it.

 

I would do this if I was back stateside. The price for machine work in Japan is ridiculous!! I have a evo 4 crank thats perfect and ready to go so I was curious if it was the same.

 

I see. The evo 4 crank is still a forged 4G63T crank. I would just double check the main journal and rod journal diameters as well as their lengths. The ACL bearing catalog lists the differences in journal lengths between different years of production, and whether or not it used a thrust bearing on the number 3 main journal or thrust washers. Apparently there was a 2V and 4V 4G63T engine. Having both cranks side by side next to each other would be the ultimate test.