i will use 86mm new pistons for my car, and i want to know the about the compression rate

because i see pistons with 10:1, 8:1
and i want to choose, i dont know what to do

 

your better off with 8:1 for all around uses

 

I'd personally run around 9:1 to 9.5:1 on a pump gas engine(non E85) Lower then that is used for high boost (35+) and will lead to a slower off boost acceleration off boost.
9.5-10:5 if you are going to run E85 all the time .
I'd also consider a stroker crank and different rods if you are building an engine. Huge gains are unleashed.