Poorman's heat exchanger

[Mingus]

heat with headers? Here you go...

Sneaking in is the elusive Towser Finn Ranger (aka shop cat). Last 2 photos show how I adjusted for fitment into the flapper box hose and hose duct in rear engine tin tray, respectively.










more details on My 911 SC Minor Overhaul

[Trog]

How very timely. I’m currently designing a new heat exchanger as my recently purchased headers failed to arrive with heat–boxes (another story entirely). I’m looking at various options that include:

1- Traditional box around header
2- Heat-Muff around the header secondaries
3- Engine oil cooler shroud
4- Muffler box

Regardless of the final configuration, the 3-T rule of heat exchanger design applies to each alternative:

Temperature – The hotter the heat source, the better the heat transfer

Time – The longer the medium is in contact the heat source, the better the heat transfer

Turbulence – Avoid laminar flow. The more air molecules that come into contact with the heart source, the better the heat transfer.

Stay tuned.

[Danny_Ocean]

Originally Posted by Mingus

heat with headers? Here you go...

Sneaking in is the elusive Towser Finn Ranger (aka shop cat). Last 2 photos show how I adjusted for fitment into the flapper box hose and hose duct in rear engine tin tray, respectively.

Have you tested this set-up? I don't believe there'll be enough heat transfer once underway. Perhaps wrapping/surrounding the headers & pipe with some sort of material that will contain the heat might help.

You might be better off getting a long-haired cat to place in your lap while driving.

[Zeke]

Sometimes the simplest ideas are the most brilliant.

[Mingus]

oh yes, i have tested it. see my rebuild for details (My 911 SC Minor Overhaul). i have been using it for 2 years through cold wisconsin springs and falls (wake her up april1 and put her to bed first weekend in november.) i did't intend to use it for warmth as much to clear the condensate on the inside of the windshield. however, it provides plenty of heat (through defrost only--you probably already know the story of the footwell blowers and removing the heater blower-Carrera - Removing Engine Compartment Heater Blower)

[Mingus]

in fact, i only have the left side (cylinders 123) hooked up and block off on the right (passenger). if i hooked up the other side, it's be steamy. all this being said, we maybe a bit more tolerant of cold here. sunny, 55F and 10mph west wind is my ideal day.

[Danny_Ocean]

Hmm...good to know. I want to switch to headers, but need some heat (mostly defrost) on some of the very few nights when it gets "chilly" here.

Thanks for the tip!

[gptom]

Is it possible to dimple/dent the face of the tubing that contacts the header. This would mean more surface area in contact

Tom

[euro911sc]

Thats steel exhaust pipe so it wont be forming around anything easily... You could use the 3" flexible home heating pipe. It is made of Aluminum and will bend and dimple easily. The AL will transfer heat better, but that is a 2 way street

I may do this... er... I know I know but it does get cold here in Florida at least 1 day out of the year! That day is usually the day of the 24 hours of Daytona too!

-Michael

[sobamaflyer]

Tom it looks like you have caused quite a stir w/ your heat solution. I was ready to give up my headers so I could keep driving my car (happily) in the winter but not anymore.

I about had a wife-sicle a couple of date nights ago where we were still out at midnight and it had dropped to 35°.

[willtel]

I recently found some pictures of home made heat exchangers when I was browsing some Japanese websites about 930s. I will look later tonight and see if I can find them again and link the pics.

[Wil Ferch]

Maybe not quite as simple as this setup here....but why not light aircraft heater muffs?--->

Home made heat exchanger

[brads911sc]

or you can save your penny's and buy a used set of exchangers from those who have upgraded to SSI's... probably get a great deal and you wont be rigging an expensive car...

[OZCarrera3]

At first I thought you were going to show us a new type of "Cat-bypass"...


Awwww.....in retrospect, even I think that was pretty ordinary!

[hangar21]

Hi everyone,
I'm new to the site and offer the following; i'm an aircraft mechanic so I'm learning as I go on 911's. There are several types of stainless steel heat boxes that are used on aircraft exhaust (same theory as our 911's). You can start with "Aircraft Spruce & Speciality" located in SoCal. I purchase all sorts of aircraft hardware and parts from them for small aircraft repair. There are several manufacturers of these heat boxes oe exchangers. After I save enough for set of headers for my car, I'm going to modifty my heating systems with these heat exchangers. Hope this helps

Terry
1987 911 cab
1990 944s2
Pitts Special S1-S (Biplane)

[Wil Ferch]

Terry.....that's what my link above ( #12) talks about and shows. One guy even makes custom lengths if you need them for not much $$$....in that link too.

[hangar21]

Wil,
I should have read your link before i replied. Nice pix.

Terry

[brads911sc]

the aircraft spruce ones are $126 each plus hardware. while a good idea, if all you want is heat, i can get a set of used exchangers for less than you will spend on that setup (About $300). why reinvent the wheel? if this is about using headers... then that looks like a good option...

[Danny_Ocean]

Originally Posted by brads911sc

or you can save your penny's and buy a used set of exchangers from those who have upgraded to SSI's.

Umm...wouldn't that be contrary to running headers?

[Zeke]

Originally Posted by Danny_Ocean

Umm...wouldn't that be contrary to running headers?

Factory exhaust from '74< is pretty much equal length. I think the lure of SSI's is for an excellent replacement and great looks. Let's face it, a lot guys like to look at the bottom side and see pretty.

Also, decent HE's are getting harder to find at 40 or so years of age.

Beyond that, used headers are dirt cheap and work well. I think the AL tube is a great idea. Contact is only part of the equation as the tube is running through a hot environment and absorbing heat on the whole surface.'

Spiral that puppy around the pipes and it would melt things in the cabin.