Which Engine Heating Duct & Blowers to Use?

[goldgunner]

Here's the deal:
1980 SC 3.0 engine with CIS converted to:
3.2 Mahle; 1984 Carrera fuel injection & manifold system; Electromotive EFI system.

After more than toying with the concepts of: Engine heater blower deleting via back dating to 1974 duct system,
I've decided to have blown heat - after all.

Thoughts: with the Carrera manifolds it makes sense - I think - to use the Carrera heater blower motor and bracket.

If I do that then maybe it makes sense to use the Carrera ducting: A. Left Side Hot Air Socket and B. the Long elbow the Carrera has (with hose) from the blower motor to the left side heat exchanger.
Yes or No?

Then I get confused...

From PET I can't figure out how the Carrera gets blower motor air to the right side heat exchanger.

For that matter I can't figure out what to do about the right side air socket...

Or maybe a combination of Carrera and ?? sockets and ducting?

Any recommendations? Pictures? Hand holding?

I'll buy the pieces that would best give Fit and Function. Some Form would be nice, but...

Thanks and hopeful,
Jim

[raceman]

the pass sd HE gets air from a stainless splitter that feeds both HE`s from the engine mounted blower motor

[goldgunner]

Thanks Raceman - that's a start.

I don't see the splitter you describe on any PET drawings...

Would you be able to come up with a part number or picture or maybe a PET reference I missed?

Anyone?

[jevvy]

from my PET pdf it shows up as 930 211 335 00 "air control tube.

Heres the pic:

detail:


good luck.

[raceman]

air control tube.good luck with your conversion

[goldgunner]

I need an education and reality check on this:

Left Side Hot Air Socket - Duct: All engines - at least late 70's to late 80's - have a left side hot air socket in one configuration or another - whether they have electric motor blown or not: Correct or Not?

Right Side Hot Air Socket - Duct:
Some of the late 70's to late 80's engines have a functioning duct and hose? And some do not - use the 'block off plate'? : Correct or Not?

Right Side Hot Air Socket - Duct:
WHY (and/or when) is the right side hot air socket and hose used?
WHY (and/or when) is that passage blocked off?

I guess what I'm getting at is: trying to determine whether I need, or should have, the right side hot air socket and hose...or whether I should block it off and use hose (or pipe & hose) to the right side heat exchanger.

All information respectfully requested and appreciated.
Thanks,
Jim

[goldgunner]

Any feedback on my last post above? Would be very, very helpful and appreciated.

Thanks again,
Jim

[Mysterytrain]

I'm not sure I understand what you have done to the engine and what exhaust system you are using. The drawing above is for a real 3.2. It sounds like you built a 3,2 short stroke..in that case most people go with SSI's and a 2in/1 out muffler..basically a 74 exhaust system.
Not sure if the 3,2 system will work..but I modified the drawing so you can see the heat flow.

[goldgunner]

Thanks Ron
More info on mine:
Yes - a 3.0 to 3.2 Mahle p & c's, with carrera intake manifold and fuel rails, with the electromotive - Clewette EFI.

Out the other side: SSI's (thick flange) with O2 sensor bung/port;
2 in - 2 out on the muffler (Triad).

I think I understand - a little: routing to the heat exchangers can be either via 1 in (down) and then split below by short hose to left HE and cross pipe to right HE, or

2 hoses down - 1 to each HE.

Where I continue to be confused is, if I'm going to use the heater blower motor, whether or not to use the right side hot air socket - or close it off.

Heck, I'm confused about when and why the right hot air socket is ever used!

Please - more?
thanks,
jim

[Mysterytrain]

I converted my 3.0 to a 3.2 short stroke and kept the CIS..I also removed the stock exhaust and heating system and went with SSI's and a dansk 2/1. I removed the rear engine blower and all of the assiciated ductwork on the engine and went witn a 74 configuration. I have a right and left heat socket that ducts air thru the engine sheet metal to the left and right heat exchangers. Once the heated air enters the car I updated the heating system to carrera style with footwell blowers. I have more heat then I every had with the old system.



you need parts, 9,10,11,12 and 19,20,21,22,23.


This is part number 9 with the cutaway to clear the distributor:


Not my engine but this is the idea:




Then for the rest go here:
heater cntrl assembly on e-brake 86 and higher

[Matt_West]

I have a stock 3.0 with SSI heat exchangers. I just recently removed the blower and backdated the heat to the 74 style using Thom's left and right ducts. We have had some below freezing days and the heat is more than adequate even when sitting in stop and go traffic.

Personally I think the blower serves to provide a consistent air flow. The squirel cage blower serves to both move air at low engine speeds and restrict flow at above idle speeds. My heating system now allows much greater heat at above idle and acceptable heat at idle. I find that I spend much more time raising and lowering the levers by the hand brake than I used to...

I am actualy concerned that the heat never seems to shut entirely off. I think come summer I will spend a lot of time with the windows / sunroof open.

[goldgunner]

Cleary - Ron - you are the footwell blower fan Master~! Thanks for the cogent and precise technical treatise. I don't think anyone could ask for or need more.

Matt - you didn't say - but am I'm interpreting correctly that you went the backdate without the footwell blowers?

Considering my rebuild's current state, I'm not willing to make the transition to the footwell blowers...probably my loss and if I'd had Ron's detail a couple of months ago I most likely would have gone that way.

So, am I interpreting correctly that the reason for using and ducting to the right side hot air socket is to increase engine hot air flow - without the need for the engine blower fan? Whether or not footwell blowers are employed - but especially when the engine blower fan is deleted?

[Mysterytrain]

I think the need for the footwell blowers is dependant on where you live. I was running without them and one very cold late november/early december evening decided to warm the car up before my wife and I drove home from our friend's house..the car was ice cold when we got in it and didn't heat up until i was able to maintain 3K rpm's. I installed the footwell blowers that winter and they made all the difference. I can start the car and let it idle for a few minutes and then bake cookies in the cabin. The rear blower was never like this.

[A_Cunningham]

Hi I'm new to this so hope I can get ron orlando, or, anyone else to help me find the part # for 9 and 10 in the 911S air ducting photo/scheme he posted I cannot find that parts photo anywhere.

AND PLEASE where to find them? I have done enough messing around with the 1980 heater motor in back and want to retro back to just that, the two hot air sockets with the slice out for the larger 80 distributor.
Thanks.

[Craig_D]

Here's what our host has:

Left Side:
https://www.pelicanparts.com/More_Info/93010632101V2PH.htm?pn=930-106-321-01-V2-PH&SVSVSI=777

Right Side:
https://www.pelicanparts.com/More_Info/91110632201PH.htm?pn=911-106-322-01-PH&SVSVSI=777

[Craig_D]

These are what I have in my 1978 911 SC after backdating the heat and using SSI headers:

edit: my left side didn't have the cutaway for the distributor, but I was able to massage it with a rubber mallet to make enough clearance.

[Jack Stands]

I wonder if the elimination of the passenger side heat duct takeoff from the engine wasn’t to allow installation of the AC bracket more than anything else. I’ve never had an issue with the non-blower assisted heating system in my earlier 911s and 914-6s, but hate the complexity of my Carrera’s system. A total of six separate blower motors in it’s heating/AC/ventilation system seems like overkill.