Air Control Tube SSI Heat Exchangers Conversion

[renders]

I am doing a conversion of a 1984 Carrera 3.2 from the stock heat exchangers to the SSI exchangers and I am planning to build a custom air control tube to route the SSI heat exchanger air outlets through the original hole in the engine cover.
I am not the first one who does this conversion and I was thinking before I reinvent the wheel I guess the wheel has already been invented
I can't find any parts off the shelf for this conversion and the Heater Hoses that are sold from our host Pelican Parts are all too short. How have others tackled this?
Just for clarification a few pictures to show what I am looking at right now:

[john walker's workshop]

that pipe is in muffler space. the carrera muffler clears it, but the two in, '74 style won't. i haven't figured it out yet either, so i do the backdate.

[Spaniard]

I am also interested in how this has been tackled by other members. The Pelican shop doesn't seem to mention this work is necessary, unlike the fitment of the oil tubes which is described thoroughly.

[E Sully]

Like John said, I went with the backdated engine sheetmetal and ducting with my 3.2 with SSI's.

[pojefferson]

What year/model would this backdated sheet metal be from? I am about to do a similar project; convert 1988 3.2L (now 3.4L) to SSI exchangers w/ duel-in muffler.

I have not yet decided on duel-out muffler or not (single outlet), but I definitely know I want/need to hook back up the heat.

Thanks.

[red911sc83]

Heres a couple shots of one of the cars I did a few years back. I fabricated a custom SS pipe and modified the SSI's to work with the factory heat.

[pojefferson]

Very nice work! Almost as if SSI designed it ;-) I'm ready to get started.

[911pcars]

All you need are early engine tins for an early, low hassle backdate. I'm doing this now on a 3.2, but with 993 HEs (a little more complicated).

Here's the parts illustration:


Items to backdate:
#5 left side hose adapter, eng. shroud to HE air passage
#6 right side hose adapter, eng. shroud to HE air passage
#18 existing on 3.2 engine (?), for hose through to SSI air inlet
#17 mirror opposite piece on left side for hose through to SSI air inlet
#14 (similar to #15) pictured is MFI version w/heat tube. There's a version for non-MFI engines w/o the metal tube.
#16 early version w/o hole (or hole can be plugged in existing metal)
2.5" (est.) SCAT hose or equiv. to connect SSIs to #5 and #6

Here's the link for part numbers: Porsche 911 Air Duct Parts

Not sure if Pelican carries these parts, but you can confirm.

Hope this helps,
Sherwood

[Walt Fricke]

I think Sherwood's diagram is a little earlier than you want for your backdate.

I'd pick parts from a 911 model which had, as yours has, the engine mounted blower motor. While not essential, it greatly improves the flow of heated air. You keep your blower and the ducting from the air shroud to the blower. You then get the Y fitting which attaches to the blower outlet. One leg of the Y crosses over the top of the fan housing, and down to the right side SSI. The other stays on the left side, and passes through the sheet metal there down to the left SSI.

So you only need the sheet metal pieces which allow flexible hose to fit through the sheet metal. One variant of that has a steel tube going through, so your flex hoses attach on either side of that tube. This is, I think, all in all a better mousetrap. To work on the upper left side of the motor it is convenient to remove the ducting there, and much better to just pull it off on top, and never have to get underneath to unfasten anything.

[911pcars]

Walt's suggestion for an SC-like blower system works too, but for engine compartment appearance, it's cluttered and un-Porsche like in it's lack of simplicity. If your 911 has footwell blowers, that should create enough airflow, yes? However, in Minn., may not be enough.

Maybe delete the engine compartment fan motor and cross-over hoses and instead adapt some inline bilge pump fans closer to the under-chassis heater valves. Should also make for easier engine accessibility.

Some discussion here:
Heater backdate with a twist
3.2 heater back date
Heat system questions
Why you should backdate your heat on a 3.2

[Walt Fricke]

When I first got a 911, it was a '77 Euro, with the desireable '74 exhausts. It was December in Colorado. And it became my ski car. Heat needed, and the blower motor on the engine wasn't, for some long forgotten reason, working. So I bypassed it, and let the engine cooling fan blow the air from the one left side outlet into the tubes to both heat exchangers. This was effective enough that it surprised me. But I came from VW beetles for ski cars, and on occasion my VW bus, so anything would be an improvement. +

Then I fixed the engine mounted Bosch blower somehow, or replaced it. Now things really cooked when the engine came up to temp. You want this blower for weather consistently below freezing.

The footwell blowers are a nice addition, but untrustworthy because of their cheap construction and tendency to melt parts and sieze up.

Red911's modification of the stock "crossover" piping down out of sight is marvelous. But it would appear to call for some serious tinsmith skills to fabricate. And in terms of ducting air, the 90 degree angle to the left heat exchanger is not as smooth as the factory system would have it, it would seem. Though doubtless it works, and maybe one need not be as fastidious as we all are when fussing with our engine air intakes.

[JohnnyT]

This is the solution that I designed back in 1999.
Need to modify the tube from the blower to fit up to the SSI inlet on the left side, and plug the inlet on the right side. Cut and weld in new connections to the SSI Heat exchangers, and fabricate the "u-shaped" connection tube. Heat is well balanced side to side and excessive!