Right sided air duct.

[Rod80SC]

I have seen a few pictures of other engines with the passenger side heat exchanger air coming right off the right side of the engine fan housing. Making for a very short run of heater hose, instead of running across the top of the fan housing. Has anyone seen these and know if they are available.?
Thanks for all your help
Rod

[surflvr911sc]

Shortly after introducing CIS fuel injection in 1974/1975, Porsche changed how hot air was sent into the passenger cabin for heat and defrosting. Starting with the first 911 in 1965, the original air system consisted of a duct on either side of the fan housing routing air through the engine tin to the heat exchangers. The mid-70's system consisted of a fan mounted high on the left upper side of the engine bay, with 3 hoses, one for an air intake
from the fan housing, and two hoses from the blower through the engine tin to each heat exchanger. Backdating the air system to the older style is easy to do, and Porsche sells the parts you'll need, or you can visit your favorite used parts dealer.

You'll need the following parts:

Left hot air duct, 930.106.321.02, list $148.20
4 plastic nuts, 999.591.592.40, list $.12 each
2 rubber plugs, 999.703.044.50, list $.77 each
Right hot air duct, 911.106.327.00, list $53.45
Right engine cover plate, 911.106.036.00, list $14.89
Right engine cover, 911.106.827.00, list $5.04
Right air duct support, 911.106.331.00, list $1.30
Hose (see below)

The left hand air duct has a bunch of holes in it to fit 911's and 930's, and the rubber plugs and plastic nuts cover those holes and allow other things to be screwed to the housing. I put a screw into each plastic nut to pretty well close off those holes. The left hot air duct is metal, and the right duct is plastic, while the engine cover and plate are metal. The right air duct support is to bolt the right air duct to the larger plastic cover over the engine. I didn't use it, as things seem tight enough without it, however, we'll see if over time I need to add the support.

Installation is straight forward, take the existing blower and hoses out of the engine. On my 81SC, the bracket that holds the motor also holds one of the vacuum pipes, so I took the whole bracket off, and cut off the portion which held the motor, leaving the portion that holds a support for the pipe. Put the left hot air duct in. On the right, unscrew the cover plate and remove it. Put in the engine cover plate, followed by the right air duct, followed by the engine cover. The right air duct has some grooves in it where the engine cover cinches it up fairly tight.

Hoses: I used 4 feet of 2 1/2" SCAT hose (silicone rubber-based, good to 450 degrees) from Aircraft Spruce and Specialty, cost $21. You'll cut two pieces for the left side (duct to engine tin, then below engine tin to heat exchanger) and one longer piece on the right (duct to heat exchanger). I've also seen an aluminum-based hose used, as well as other types and colors. The hose has to stand the heat in the engine compartment and more importantly the heat at the heat exchanger connection.

That completes the installation. Assuming your heater boxes are working, and the wires to the heater controls on the floor are also intact, you're done! Not much heat at idle, it picks up well as the revs increase. If you open a window just a crack, then that helps the heated air move into the compartment. And, especially if you've removed your air conditioning compressor, you can now see a lot more of the engine!

[SpeedracerIndy]

If you want to keep the ability to use a blower motor, but get rid of the ugly tube going over the top of the engine, you can "half" backdate it. That is what I did. I plugged the Y splitter comming off of the blower going to the right side. The car was already backdated by the PO, so I jsut left the right side parts on there. Much cheeper than the full backdate and you get the benefit of some heat a idle, and get rid of the ugly hose over the top. I'll try to get some pics soon since it's warming up here.

[SpeedracerIndy]

Here are some pics: Top one is backdated on both sides, bottom is backdated on the right side only.

[sammyg2]

On a 911 SC with air conditioning, what do you do to backdate the passenger side? Is there an early duct that can go from the right side of the fan under or around the air conditioning compressor?
TIA

[surflvr911sc]

Sam get these...

Right hot air duct, 911.106.327.00, list $53.45
Right engine cover plate, 911.106.036.00, list $14.89
Right engine cover, 911.106.827.00, list $5.04
Right air duct support, 911.106.331.00, list $1.30

They should fit fine w/ a/c, no bigger than the hose that goes that way reallly.

[sammyg2]

Tanks
Now to go search the pelican site to see if they sell those things.

[Rod80SC]

Great response guys, thanks. While my first intention was to just do the "half back date", I am now all over the total backdate. My blower motor is shot anyway. CD, the pics were great examples, and Ryan all the info and parts numbers will be a big help.
Thanks again
Rod

[Wyoporsche]

Has anyone completed this back date while keeping the AC compressor? Would this be possible? I have a 2.7 and want to find out how to do this.
thanks

[TastyReuben]

Im in the middle of this now. I have seen several people cut a hole into the passenger side cover plate to add a 90 elbow, secure with JB weld and repaint, that will fit behind the AC compressor bracket. I have seen others 'massage' those back date plates with a hammer to make fit.

if anyone has a link to one that fit behind the AC bracket, a link/pictures would be helpful.

[Wyoporsche]

I'm surprised there isn't more information on this or that someone hasn't dialed this system in more.

Any direction others can provide is welcome.

Thanks tastyreuben for the reply. if you have any luck with this please provide some photos.

[dg567]

It can be done with all porsche parts that are available, you just need the early parts. Hard to see on my engine but everything is tucked very neatly under the AC compressor.

#5 & 6 in the diagram below

https://www.pelicanparts.com/More_Info/91110603600.htm?pn=911-106-036-00-OEM

https://www.pelicanparts.com/More_Info/91110632700.htm?pn=911-106-327-00-OEM&bc=c&SVSVSI=

[TastyReuben]

thx for the diagram, now I see how parts listed above go together to make it happen. $320+ is a bit much for something you cant see, will try adding an elbow to my existing cover plate first. Solid backup plan if I muck it up too bad though.