Has anyone built their own heat exchangers for a six conversion? It would be so nice to have a little heat for those cold mornings with the top off...and some defrost for rainy days...but I can't see laying out over a thousand bucks for manufactured exchangers. I have a friend who is a master stainless fabricator but we need a plan and some guidance...what works and what doesn't. I'd like to retain as much access to lower valve covers as possible and I don't need tons of heat. Engine is a 2.4...headers are pictured below. Thanks for any insights offered.

I have been involved in 914's since the 70's and I have never seen anybody make a home made heat exchanger.
Of course I have been wrong from time to time so who knows....
GHL and B&B are the only company's that I know of that make aftermarket 914-6 heat exchangers.
Both company's are in AZ.
You might be able to look at there web sites and try to copy it....

Dan on this site has a prototype set he is working on.
I believe he is starting out with a different set of 911 headers...

this thread comes at a good time, as I'd love to see an update on Dan's set.. and am trying to figure out what to buy to make a set for myself.

Dan??????
are you out there?????

Dan was just welding a pipe to the outside of the headers. Then he would run air through them. Simple, and practical. I agree, I would like to see more on it.

Hey Mike,

hope you had a good weekend.
I'll write out my bills tonight and get some money in the mail to you!!!!!!! (pay day is tomorrow)

hope the packing is going well!

brant

Brant,
Your dash was done, but then.........I kinda had an accident that caused a small tear in the new vinyl. It will be done tomarrow.

I aint packing yet. I got too many damn parts/projects to deal with

QUOTE (Dr Evil @ May 30 2005, 11:26 AM)

Brant, Your dash was done, but then.........I kinda had an accident that caused a small tear in the new vinyl. It will be done tomarrow. I aint packing yet. I got too many damn parts/projects to deal with

Hey...
I'm in no rush for it.
don't make a special trip down there or anything for me.

------------------------------------



Dan, jump in here about your heaters!

brant

QUOTE (Dr Evil @ May 30 2005, 10:17 AM)

Simple, and practical

Oh and DEADLY too!

Here we go again on this topic. I hope 'ol Back Yard Bob has good product liabiltiy insurance, as home-made heat exchangers from mild steel is a lethal combination.

Porsche learned a long time ago how deadly heat exchangers can be. Ever since the early sixties all Porsche exhaust systems have exhaust tubing made of a low grade stainless, and heat collectors of mild steel. Ever wonder why the heat collectors on 914 h/e's rot away, but the pipes look ok? Also there aren't ever any welds inside the heat collectors.

This is penny wise and pound foolish bull!

But look at it this way, all that money you save will go towards a great casket!

Perry,

I believe the 2nd generation set (the one I'm interested in learnnig about)...

actually uses a set of early 911 STOCK heat exchangers..
then the ducting is modified to bring heat into the 914.
but this relieves some of the concern about the exhaust gasses killing you.

brant

Thanks Perry....hadn't really thought of the CO danger. Definitely not to be ignored! A couple ideas come to mind...use stainless headers and mild steel heat boxes so the box rusts before the header pipe? The factory plan, right? How about steel headers with stainless boxes that incorporate a stainless sleeve inside isolating them from any potential leaks? Would probably need some material between header and sleeve to insure good heat transfer. Also perhaps there exists some kind of CO monitor/warning device that could be installed in the cockpit....seems like a good idea for any manifold heat system. On the other hand, 90% of my driving is done with top off...but there's still that other 10%...and the possibility of exposing the unwary or future owner to the danger.
Thoughts?

CO exposure is always a bad thing. Even with the roof off. I was out for a cruise a while back after reconnecting all the heat ducts. Roof off, heat on. My girlfriend is with me, and starts complaining about feeling dizzy. I later stopped by the local fire station and asked one of them if I could borrow a CO detector. Turns out I had a nice leak, 60 PPM, and they said that exposure to that level, even with all the fresh air, could cause a person to lose consciousness over 30-60 minutes.

Always avoid CO. Talk to your local FD if you want brand recommendations for good in-home CO detectors. It is at least as important as having working smoke detectors!

It doesn't seem to hard to rectify the problems mentioned. Weld a stainless pipe like structure to the outside of the headers. This way there is no exhaust running throught the box. If the exhaust rusts, oh well. You could have the air drawn in from some where other than around the exhaust so a breach in the exhaust system would be inconsequential regarding CO getting into the cabin air system. Also, a solid pipe/tube would have no seam inside the exhaust system to worry about rusting out. just the weld between the pipe and the header. From the old post, the only problem that I remember was where the air intake was coming from, and how. Pushing air through was reasoned to be better becasue you would have less worry of sucking exhaust gas into the system andyou could pick where you were getting air from. A suction system would draw air from any leak in the system leaving a weak point by the exhaust link potentially.
What in this line of thinking strikes any of you as incorrect, or dangerous? What concerns are left to address?

I was one of those few who bought the B&B headers, they were the most expensive purchase in my conversion project. I don't recommend them, the fitment was poor, the boxes block access to the header studs, and there are air leaks between the tubes and the boxes.

Have been toying with the notion of putting a BF aftermarket alternator where the AC compressor used to be on my 3.2 and using it exclusively to power heating elements for cabin heat, butt warmers, defrost, etc. Haven't yet checked if the firewall will let me do this though...

You might want to take a look at the heat exchanger Racer Chris offers for his Type 4 header systems. There are some photos on his site. He makes some beatiful headers.

http://www.tangerineracing.com/Super_Heade...EAT%20EXCHANGER

portable CO detectors: http://www.detectorsandalarms.com and http://testproducts.com/safecart/index.php...37d657a9e91ed92

some specifically for use in vehicles: http://www.safehomeproducts.com/SHP/SM/Cos..._Alarms.asp#P-1

The system I made was a 2" exhaust pipe welded to the header pipes. Not around them, just to them. So I don't think fumes would be an issue since the pipe was so thick and never split. It worked great, just cooled off too much when you hit the freeway.

But luke warm air was much better than nothing.

In town, they worked great.

When I had a 6 conversion, I toyed with the idea of running an oil cooler as a heater core, just like a water cooled car. Mount it low in the engine bay with ducting to blow air through the cooler and into the stock heater tubing seems like the best way to do this. Never pursued it, and I don't know of anyone else who did, either. No possibility of CO poisoning, and you gain a bit of cooling in the deal.

QUOTE (lapuwali @ May 31 2005, 01:04 PM)

When I had a 6 conversion, I toyed with the idea of running an oil cooler as a heater core, just like a water cooled car. Mount it low in the engine bay with ducting to blow air through the cooler and into the stock heater tubing seems like the best way to do this. Never pursued it, and I don't know of anyone else who did, either. No possibility of CO poisoning, and you gain a bit of cooling in the deal.

Thats a very interesting idea. I wonder if you would get enough heat?

If you had a thermostat on the external cooler, it would probably be closed in cold weather when you need heat the most....but you'd have lots of heat on hot days.

Dan,

care to elaborate about version 2 and the other type?

or if that is a development secret then I understand.

brant

QUOTE (goose2 @ May 31 2005, 11:23 AM)

If you had a thermostat on the external cooler, it would probably be closed in cold weather when you need heat the most....but you'd have lots of heat on hot days.

Run it in place of the on-engine cooler, with an electric fan to force air through it. Have a flapper valve controllable with the stock lever to direct exhaust air into the heater tube or out onto the ground, just like the HE setup. No overcooling the oil, and it should be at least 170-180d even on cold(ish) days, which should at least be enough to demist the windscreen. It's rather elaborate, but you're not stuck with using or making exhaust heat exchangers. Running the only cooler externally also helps one of the common stumbling blocks in doing a /6 conversion, which is getting the oil tank plumbing to fit within the suspension.

Here is what I had in mind. Mine has twice the length of the one Dan did, I think. It would consist of some high grade steel tubing that draws from the usual place off of the fan and unloads at the same place in the rockers. Tenatively. I am sure some mods will have to be made to avoid shifters and such, but I still do not see why this would not work.

QUOTE (ss6 @ May 31 2005, 08:53 AM)

I was one of those few who bought the B&B headers, they were the most expensive purchase in my conversion project. I don't recommend them, the fitment was poor, the boxes block access to the header studs, and there are air leaks between the tubes and the boxes.

I've sold about six sets of the B&B, and won't sell any more. Too many problems. For the kind of money they get, they should fit right and give more heat.

GHL is making some stainless headers with heat now. I haven't got a set in my hands though to see how good they fit, but they look better than Billy's bull.

I had a conversion customer in Memphis who was going to try the oil cooler/heater core approach. Don't know if it ever happended though.

No doubt a factory style heat exchanger system is the most efficient, but......

On a different approach, I've got a barely used Webasto gas heater that I'd like to use on a conversion some day. Now those things put out heat!

Here is what I did on the flared orange 914-6. Used a stock electric fan on each side.

I even labeled the arrows blue for cold air coming in.

And the red arrows as it heats up.

Really, the system worked great until you hit the freeway and the tube I welded to the headers cooled down a little. Then the air was luke warm, not hot anymore. I tried welding on a heatshield, which helped, a little.

I will be trying something different though. Watch for it.

Dan,
I noticed (I think I did ) that your set up only attaches at one spot on the header. We are needing to work in the reverse of what we are used to, i.e. conserve heat, not release it. If you just bent the pipe to match the header and welded the whole length of the header where the pipe is, you would have much better heat transfer and I would imagine that the cooling down problem would dissappear. I bet that you already knew that/thought about it. Just putting it out.

Also, since I am using the wall mount I will have less constriction issues with routing the hose.

Keep it coming.

I bet that if you used a smaller diameter pipe and routed it like my diagram shows, you would melt stuff. I am thinking that this would be the case because you were getting deacent transfer with your one mount point and a single pass pipe set up.

Pretty clever, Dan....did you do this on both sides or only one? Looks safe and simple. I've got some ideas too...perhaps we could compare notes? Also...got the tach you sent. It cleaned up good and works fine, thanks....and I got the dipstick measurements from Patrick MS. Still need to talk to you about motor stuff though...when's a good time to call? Enjoying the orange car....takes an hour to get the grin off my face every time I drive it.
Randy

Mike and Randy,

Yep, did this on both sides. I went back through on just the drivers side and added more welds to help the heat transfer. Then I also added a heatshield to the bottom to try to prevent cold air from hitting the heating tube.

Mike has a great idea, smaller tube running more closely along more of the header pipes.

I was really close, really close to the system just being a turn on anytime and get hot air system. Just the freeway part was a bummer.

with one fan on each side, it would blow air through the defrost vents enough to make your hair move (provided you have hair).

Simple, clean and still easy to remove the headers. Light too.

QUOTE (goose2 @ Jun 1 2005, 08:10 AM)

Pretty clever, Dan....did you do this on both sides or only one? Looks safe and simple. I've got some ideas too...perhaps we could compare notes? Also...got the tach you sent. It cleaned up good and works fine, thanks....and I got the dipstick measurements from Patrick MS. Still need to talk to you about motor stuff though...when's a good time to call? Enjoying the orange car....takes an hour to get the grin off my face every time I drive it. Randy

Hey Randy, Call in the evening, like after 5PM works pretty well for me. I am usually home by then.

Glad you like the orange car. That 2.4 rocks!

You still gonna put those headers on your 914-6 then? I'll take the ones I made from you off your hands.

QUOTE

provided you have hair

Hey, you takin to me