O-ring sealed throttle body adapter for the perfectly sized 68mm bosch throttle body. This maximizes the area you can get out of the OEM intake manifold with porting.
We started with scanning the OEM intake manifold to find the ideal maximum shape based on wall thickness and flange face width for sealing. Using the adapter to mark the flange face a somewhat odd shaped area can be marked out for porting to match the adapter. The taper of the adapter keeps to a maximum of 5deg change to smooth air transition as much as possible given various constraints.
The seal is from a -041 viton O-ring held in place with a bit of RTV in the O-ring groove and left to cure.