Pelican Parts Forums - SSI's and heater duct mods

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- - SSI's and heater duct mods (http://forums.pelicanparts.com/porsche-911-technical-forum/90011-ssis-heater-duct-mods.html)

:confused: This might be a dumb question, but shouldn't air be constantly flowing through both heat exchangers as the engine is running to help cool the exhaust, hence the exhaust valves and guides as well? :eek:

Joe and Marc, thanks for the replies. But no, I didn't mean the heat shield from the "cat". Marc, as I visited your site, since you havd a 3.2 conversion, I found the answer. Here's the picture from your site. ;) Thanks Marc.
Andy
'87 Carrera

Not one of my most ingenuous mods :rolleyes: but glad it could be helpful.

Cheers

Quote:

Originally posted by Porschephanatic
:confused: This might be a dumb question, but shouldn't air be constantly flowing through both heat exchangers as the engine is running to help cool the exhaust, hence the exhaust valves and guides as well? :eek:

I know this thread is old, but have to comment here. This is not a dumb question, in fact Porsche engineers added the heat blowers into the engine bay for two reasons 1) to provide more heat at idle 2) most importantly to help keep the exhaust exchangers cool! So if you pump air through only one heat exchanger you will be running that cylinder bank cooler than the other. For this reason it is always best to pump air via both heat exchangers.

In my 75 2.7L 911 the heat blower in the engine compartment ran all the time by design, even in the summer! Now I have a 84 Carrera and in this setup the blower only runs if you pull the heat levers up near the hand brake. I decide to change this design and I put a switch in the center console between the seats so I can turn on the rear Heater Blower even in the Summer with the heat levers closed. This helps reduce my engine temps in 90degree weather by 10degrees or so. Cheap cooling modification for Carrera 3.2L owners! Or some folks adjust the switch in the heat levers so it comes on by just slightly lifting the levers, this keeps things stock and also works well.

Another question for SSI's. What is everyone doing for the two sheetmetal flanges on the exchangers to the block? Areas circled in red. Self tapping screw? Drill and tap a small bolt? Thanx, Dukehttp://forums.pelicanparts.com/uploa...1165416978.jpg

Duke,

Mine were left loose as they were not really aligned so as to fit. If they do fit I believe that they take a 6mm bolt but be sure not to bottom it out in the case or it might crack.