Certainly a valid concern. We too were worried about the same thing as we started the initial design and testing. But it turned out never to materialize. We were all ready to thermal-wrap anything and everything, then after months of checking/measuring/inspecting we never saw any indication that anything was getting an excessive dose of IR, or convection heat. (We did tie the A/C refrigerant line up and away, and did aluminum wrap it for good measure.)
As we were fitting the turbos, we needed a bit more room towards the front of the engine. This was obtained by removing the 1' x 4' plastic belly pan. We think this action also increased the airflow around the header area substantially, and likely part of the reason we see no heat issues.
It is also interesting to note that in all the later Boxsters (and Cayman), Porsche placed cats in about the same region as we have placed the turbo. The cats get mighty hot and radiate about as much total heat as a turbo. Also interesting that although Porsche put shields around the rear cats, they did not place any shielding around the header cats.
The engine bay fan did not seem to come on any more often than the stock did. It would seem to come on typically when the vehicle was sitting idling for a few minutes, usually with the A/C on, and seemingly only on the hotter days. But then would shut off after a minute. It's possible it was coming on more often, but we just never noticed it as being more than stock.
-Marc
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Originally Posted by MNBoxster
Hi,
My biggest concern would be Heat Management of twin turbos in a mid-engine setup. I have a mid-engined car w/ single factory turbo and despite having two NACA ducts and under-body channeling specifically to push massive volumes of cooling air through the engine bay, it still gets VERY hot. And this car has 30% more radiator surface and a cooling system w/ 1 gal. greater capacity than the Boxster. I've yet to be convinced that this issue won't have longterm effects on any number of ancillaries, Sensors, wiring harnesses and the tranny, especially the tiptronic. At least w/ a Supercharger (which has other issues) the Heat is not such a problem. Just my $0.02...
Happy Motoring!... Jim'99
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