The bore pitch (distance between cylinder centerlines) for the ZZ engine family is 87.5mm. So the bore on a ZZ engine has to be smaller than 87.5mm (I don't know how close to a 87.5mm bore you can safely go).
I did read Rado's Celica will use a 83.5mm bore (up from 82mm stock).
As I think my engine will always be normally aspirated, I'd like to know how much boring and stroking could be performed on the ZZ engine family, too.
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