If we have 400 engine whith 9.5 CR and destroked it to 377

using same pistons how much would CR be?

 

Its helpful to know more details about the setup.
Just use a calc like https://www.camaroz28.com/calcs/cr.html and you should be able to figure it out.

I would move this to a general tech forum exept i have no idea what vehicle you have. Could you use the sig feature so that people know what your working with? Thank you.

 

I am planning to turocharge a 400 engine whith 350 crank

and using flat top pistons to get close to 8.5 CR because I hear

that flat tops are best.