InnerDiameter of Primary Coil.

Does anyone know if the size of the inner diamter of a primary coil would 
affect performance? Currently i'm building the primary and i have planned to 
use an 8" diameter to fit my 6" secondary in between it. But, i have just 
obtained some 8" diameter pvc and i would like to fit a 8" secondary on my 
coil. In order to do that, my primary would need to have a 10" inner 
diameter. Now the big question is.. would the primary w/ a 10" diamter and a 
6" secondary work the same as a 8" primary and 6" secondary?
Thanks ahead,