Heat exchange hose question

Blitzkrieg · 01-08-2004, 04:44 AM

Hi All,

As this is my first post, i just wanted to say a big thank you to everyone on this board. I have learnt so much from you guys!

I bought my first 911 a couple of months ago and am planning a couple of upgrades including exhaust upgrades etc.

While looking at my engine bay, i was a little curious about the 3 big hoses...2 of which connect to the heat exchanges and the third one connect to the engine somehow. I have looked at the engine bay pics posted here and have only found about 2 or 3 engines with these hoses set up like mine.

So my question is, what do these hoses do? And while i'm asking about heat exchange related stuff.....are heat exchanges and headers the same thing??

Thanks guys!

Blitzkrieg

AirCooledExcellence · AirCooledExcellence's Garage

Hi,

They route air through the heat exchangers which in turn feed the heater flapper boxes that vent hot air into the cabin.

Cheers,

Tim.

RoninLB · 01-08-2004, 05:34 AM

back dating your cabin heating system without those big air hoses is a consideration..

yelcab1 · 01-08-2004, 06:06 AM

"Cold fresh air (it's a relative term) is sucked in by the big engine fan, routed to the small electric fan (often dies) by the big plastic crinkled hose on the left, rerouted by the electric fan to the two smaller paper hoses to the left and right heat exchangers where cold air becomes hot air. Hot air then is delivered to inside the cabin via two air-valve boxes under the car when you want to stay warm.

chrisp · 01-08-2004, 07:59 AM

Heat exchanger is a header with a box built around it. The air inside the box gets heated by the header pipes and is used to heat the passenger compartment. It's the heating system in a 911. Around here when you here about headers they are often talking about equal length pipes from exhaust port to muffler without the exchanger "box". The OEM system is always a heat exchanger. 1975+ systems do not have equal length pipes inside the exchanger "box" so they are often replaced by a system of the 1974 design or by regular headers. Regular headers are not capable of heating the passenger compartment but they are simple and lighter. The track junkies like them. I am a track junkie but I like the heat exchangers because it lets me defog the windshield. I have seen plenty of folks need to come into the pits on rainy days because they cannot see out of their windshields.

Have fun with your car and with this BBS!

Blitzkrieg · 01-08-2004, 10:36 PM

Thanks a lot guys....explains things perfectly!......you guys rock!

Victor · 01-09-2004, 01:05 AM

Hey Blitz, good to see another Melbourne boy on board.

Blitzkrieg · 01-09-2004, 02:30 AM

Thanks for the welcome Victor.

VaSteve · 01-09-2004, 04:39 AM

At the end of this thread is a nice diagram showing the airflow directions. A kind soul put this together for me and another explained it (so I could understand

)

Photo request - SC engine removed

SpeedracerIndy · 01-09-2004, 05:53 AM

Quote:

Originally posted by RoninLB
back dating your cabin heating system without those big air hoses is a consideration..

You could also half-back date it. When I bought my car, the PO was kind enough to have backdated the heating already for me. The problem with that is that with COLD Indiana weather, you get zero heat when idling. So, I left the right side back dated, and reinstalled the left side with the blower, then pluged the Y splitter that blows air through the right side heat exchanger. It works pretty well. I get a good amount of air flow at idle, and a LOT of air flow at above 4k rpms. Plus my engine bay still looks pretty clean. I need to get some pictures of it to show it off.