Adapting 993 Heat Exchangers to 964 Engine
In order to use the 993 heat exchangers on a 964 engine you need to rotate the flanges on the right hand exchanger. Using the aluminum adapters shown below is an option but seems only a temporary fix as the aluminum adapters tend to distort and subsequently leak.
You can see how they are distorted in the picture below.
Flipping the flanges and re-welding is a
simple and permanent fix. I need to thank Pelican member Kevin Stewart for providing the
jig.
From the inside of each exhaust port using a
Dremel and a cut-off wheel cut through the exhaust tubing just below the weld,
this will allow you to rotate the flange and fit the tubing back into the flange
and reweld.
Once you cut through the pipe, you should be
able to pop off the flanges.
Next bolt the flanges to the jig which rotates
them 90°. Leave the bolts loose and then fit
the flanges to the exhaust tubing on the heat exchangers. Once they are
fit then tighten down the flanges to the flat surface of the jig.
Now you are ready to tack the flanges on and
then remove the jig and test fit on the car. If you are happy with the
fit, reattach the jig and weld the flanges on fully.
I welded them at the
base of the flanges as this was easier than welding inside the exhaust tube and
also doesn't require grinding down all the welds to maintain nice smooth ports.
Once you are satisfied with the welds bolt them up to the car. One thing
to note is that the 2 holes in the heat exchangers that previously allowed
access to two of the barrel nuts no longer line up. I didn't have any
trouble reaching the nuts with the flanges rotated, one of the middle bolts is a
little tricky but can be done.
