Another heat exchanger question

Reuben911 · 01-20-2018, 02:27 AM

I replaced my heat exchanger with headers. Can someone send me a diagram of sorts to show the air flow direction. Don't understand where and what I should be blocking off.

1984 Porsche 3.2 911

I can't see a place for the engine block offs. All I see is a hole on the left of the engine tray

mepstein · 01-20-2018, 04:52 AM

3 & 9 o’clock on your engine fan.

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by Reuben911

I replaced my heat exchanger with headers. Can someone send me a diagram of sorts to show the air flow direction. Don't understand where and what I should be blocking off.

1984 Porsche 3.2 911

I can't see a place for the engine block offs. All I see is a hole on the left of the engine tray

It depends on what mods you are willing to do, w/o any mods on top the air for heat flows from the fan on the left side of the engine through the down pipe

there on a stock 3.2 the air goes into a manifold the splits the flow diverting ~1/2 to each side where it flows through the shroud on the headers and then up into the chassis flow control valves

Here starting on the right is the factory 964 heat manifold to the left of a non factory muffler, the down pipe can be seen at the top, 3.2 is similar though different in detail. Air comes down the down pipe through the manifold and diverted into the L/R header shrouds, it comes out the forward end of header shrouds, here left end, and into the up pipes which go to the factory air valves mounted on the chassis the valves are hidden above the half shafts here. Thes header use the stock factory heat manifold

These headers are SSI they use a different routing than the above factory design. Here the flow is still through the stock down pipe , which is hidden on the left. There are no off the shelf solutions here, I fabricated a splitter that collects the downpipe air and the diverts it to the left and right through the ducts visible here, On one car I run the cross duct through the rear bumper on this one through flex ss pipe either way works fine

here you can see the chassis air valves

The other way to connect to the SSI involves back dating to the '74 and earlier design where the air is solely pumped by the engine cooling fan, in this design there are 2 downpipes one on each side fed by ducts that come out the lower sides of the engine cooling shroud

Here a 2/7 where you can see the right side down pipe, there is another hidden on the left

mepstein · 01-20-2018, 06:08 AM

Bill V. I'm pretty sure the OP wants to remove heat, not add it.

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by mepstein

Bill V. I'm pretty sure the OP wants to remove heat, not add it.

My bad

Reuben911 · 01-20-2018, 05:48 PM

I am going to have a closer look today.

From what I saw yesterday, the is a metal plate that looks like the one I posted @ 3 o'clock but nothing at 9.

Will keep you posted

douglas bray · 01-20-2018, 06:07 PM

On a 3,2L the right side is already blocked off. You only need to block off the left/driver's side. Remove the heat blower and big plastic tubes going in and out of the heat blower and replace the diverter with the block off plate.

douglas bray · 01-20-2018, 06:11 PM

This is my engine with a heat blower bypass. Compare it to the engine above with all the blower tubes and fan. You engine will have even less on it as it won't even have the orange tube.

HaroldMHedge · HaroldMHedge's Garage

The air flows from the engine fan going thru the duct on the left side of the engine to the heater fan then back to the crossover pipe under the sheetmetal. The crossover tube should have been removed when the headers were installed.

You can remove the fan, two ducts at the fan and the rubber at the sheetmetal to crossover tube. Install the left cover plate. It is easier if the distributor has been removed.

You will not need the right cover plate since the 3.2 did not supply air to the heat exchanger from the right side under the A/C compressor.

Edit
Others were faster at the right block off.

Brian Cameron · 01-20-2018, 07:14 PM

Quote:

Originally Posted by mepstein

Bill V. I'm pretty sure the OP wants to remove heat, not add it.

Well maybe OP wants to remove heat but I appreciate Bill’s post & info all the same. Just got SSI’s and heat is a must in Canada’s rocky mountains, even in summer. Thx Bill.

douglas bray · 01-21-2018, 04:42 AM

There are also flapper box delete plates out there so that fumes don't wander up through the ducts. Flapper boxes are usually rusty and decrepit at this age and in need of replacement anyway when heat stays. I swapped out auto-heat for manual pulls.

mepstein · 01-21-2018, 06:59 AM

On 914’s, we use a cap from a spray can with a hose clamp to block off the heater tube at the longitudinal. Sounds ghetto but it’s actually pretty clean.

Reuben911 · 01-21-2018, 09:22 AM

My bad, I took a pic from the web of a 3.2 engine but apparently mine is different.

If you look at the pics it looks like it already has some sort of block off's.

So based on my pics all I need to do is do the blocks offs to the cabin ? I don't want to throw away silly money to get the ones from a dealer, what diy options do I have ?

douglas bray · 01-21-2018, 03:54 PM

Yours is a normal 3,2. You need the left side block off available at some place called Pelican Parts or some such.

Reuben911 · 01-21-2018, 06:24 PM

The left side is the location of the distributor.

I can't see anything that can fit in there as the air duct (first Pic) is right up against the fan casing.

Help

Reuben911 · 01-23-2018, 05:37 AM

I think I now understand a little more what's happening here.

I have no intention of removing any of the hot air ducts and air pump. I terminated the opening on the engine tray underneath the car (left side) and disconnected the electrical unit to operate the hot air.

With that being the case, is that now a closed system and no need for a block off plate ?