Which one, and how?

When we decided to reproduce a Porsche® air cooled flat 6 engine case, the dilemma was which one exactly we should invest in making. It was a hard decision; there are many great cases. We were initially partial to an aluminum version of a 7R mag case, but that has its limitations. Some suggested an RSR case, with its associated head stud spacing.

In the end, we went with a 3.6 964® style case, for several reasons.

  • It was latest air cooled design present, and was carried over virtually untouched to the 993® and was even the basis of the 996® twin turbo and GT2® cases.
  • It has the largest spigot size available from the factory
  • it seems to be the rarest and most desirable case in the aftermarket, and still remains difficult to find used.

We had a 3.6 case on hand, so we decided to use it as a basis for reproduction. Cases, however, are fairly complicated parts to reproduce; it was critical that the case be able to accept standard internals, and thus the dimensions of the case were critical.

The only real way to capture the case dimensions was to have each case half scanned, and so that’s what we did. We scanned each half to 50 microns, and then created a mesh model from that scan data which was then extrapolate into an IGES / STEP file by an engineer. From there, it was converted into a Solidworks .sldprt file, with a full feature tree.

A full feature tree allows us to use Solidworks to change any part of the case design on the fly, while having the software adjust the remaining parameters. Want bigger spigots? No problem, it’s a mouse click away.

To say that this process was insanely expensive and laborious is an understatement. It took a team of people the better part of  to generate a workable .sldprt file from a scanned case half….

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