Modified heater boxes for better flow
- Marc
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Re: Modified heater boxes for better flow
Why limit the heat source to the exhaust system?
I'm really surprised that no one has proposed simply modifying non-fresh 40HP heater boxes. Sure, there's a good reason VW went to freshair (NFA with loose heads or oil leaks is smelly at best, deadly at worst) but it works just fine on a healthy engine. When Corvairs first came out they only had gas heaters, but those were dropped in `64 and the "direct air" (NFA) heat was used through the end of production in `69.
I'm really surprised that no one has proposed simply modifying non-fresh 40HP heater boxes. Sure, there's a good reason VW went to freshair (NFA with loose heads or oil leaks is smelly at best, deadly at worst) but it works just fine on a healthy engine. When Corvairs first came out they only had gas heaters, but those were dropped in `64 and the "direct air" (NFA) heat was used through the end of production in `69.
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Re: Modified heater boxes for better flow
Marc,
I actually used a bus/914 blower fan, located under the backseat of the Ghia. (to pull in cabin-temp air)
this goes through two outlet tubes to feed the heater boxes.
The electrical portion is handled by the normal (non functional) rear window defrost circuit. The under dash switch controls an additional relay mounted on the firewall. The relay is hooked straight to the battery, protected by a 5A aircraft circuit breaker, because I found it before I found a fuse holder.
I currently only have it hooked up during the colder times. Once the ambient temps go over a high of 90F, I return the system to original config, so that the fan shroud is connected again (in order to retain optimal cooling).
Observations;
It works pretty well.
It actually will defog the front window!!!!!! I no longer can watch the window fog over at a stop light.
The output of the electric fan circuit is higher than the engine driven fan while if the engine is below cruise speed.
Conclusion: During a city driving regime, where lower speeds, and prolonged idling is involved, the electric fan is a worthwhile conversion. If you drive a majority of highway, the orig setup has a higher output.
I am still interested in the better heaterboxes since I am about to begine an engine build.
I actually used a bus/914 blower fan, located under the backseat of the Ghia. (to pull in cabin-temp air)
this goes through two outlet tubes to feed the heater boxes.
The electrical portion is handled by the normal (non functional) rear window defrost circuit. The under dash switch controls an additional relay mounted on the firewall. The relay is hooked straight to the battery, protected by a 5A aircraft circuit breaker, because I found it before I found a fuse holder.
I currently only have it hooked up during the colder times. Once the ambient temps go over a high of 90F, I return the system to original config, so that the fan shroud is connected again (in order to retain optimal cooling).
Observations;
It works pretty well.
It actually will defog the front window!!!!!! I no longer can watch the window fog over at a stop light.
The output of the electric fan circuit is higher than the engine driven fan while if the engine is below cruise speed.
Conclusion: During a city driving regime, where lower speeds, and prolonged idling is involved, the electric fan is a worthwhile conversion. If you drive a majority of highway, the orig setup has a higher output.
I am still interested in the better heaterboxes since I am about to begine an engine build.
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Re: Modified heater boxes for better flow
Thinking "outside of the (heater) box"sideshow wrote:Well I can tell you for certain that adding 24 feet of copper tubing to the inside of the common 1 1/2 heater box does nothing for interior heat and is a total pain in the ass.
Personally I was amazed, I thought I was really onto something.
What about taking the above copper tube wrapped J pipes in the diameter of your choice, then plumbing the tubing into a heater core inside the car, with a blower fan............
anyone picking up on what I am laying down here?
- turbobaja
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Re: Modified heater boxes for better flow
I like the idea of including the heads in the heater boxes. Their tendency to leak and give off poisonous fumes is kind of a deal breaker though. It would be interesting to try it on a fresh, well sealed engine. Something similar to cool-tins could be fit around the fins of just the heads and ducted out the bottom, or directly into the exhaust heater boxes to get every bit of heat the engine has to offer. Sounds like a good way to cook the heads if you're not careful , but I'd still like to give it a try...
A gas heater makes more sense every time I think about it . It's BTU output has no relation to load on the engine. It would add a small electrical load for it's blower(s?) and what ever fuel they consume of course. Finding room for it and plumbing the fuel and exhaust would be the challenge, on top of locating and paying for a functional unit to begin with. But it would simplify the back end quite a bit...
I think the copper piping to plumb water to a heater core would end up being more of an exhaust cooler than an good source of HOT coolant to heat the interior. But that's just a guess. Your setup with the blower recirculating interior air through the heater boxes sounds a lot like mine helowrench, it's promising to hear that it defrosts well . I've yet to even test for air-flow with my pair of blowers hooked up, but I'm getting real close
A gas heater makes more sense every time I think about it . It's BTU output has no relation to load on the engine. It would add a small electrical load for it's blower(s?) and what ever fuel they consume of course. Finding room for it and plumbing the fuel and exhaust would be the challenge, on top of locating and paying for a functional unit to begin with. But it would simplify the back end quite a bit...
I think the copper piping to plumb water to a heater core would end up being more of an exhaust cooler than an good source of HOT coolant to heat the interior. But that's just a guess. Your setup with the blower recirculating interior air through the heater boxes sounds a lot like mine helowrench, it's promising to hear that it defrosts well . I've yet to even test for air-flow with my pair of blowers hooked up, but I'm getting real close
Karl
DON'T QUIT
DON'T QUIT
- Marc
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Re: Modified heater boxes for better flow
I think it would probably work. Not sure natural convection would provide enough circulation, an electric water pump would probably be needed...and there'd have to be an expansion tank, even if run at atmospheric pressure. To get the hottest coolant you'd want to pass it around one side and then back up around the other, so one J-tube would end up running cooler than the other but that probably wouldn't cause any trouble. I thought of doing it decades ago (Lee can attest that this is one of the oddball ideas we were PM'ing about) but thought better of it after considering the complexity of the job. Besides, I'd no longer have been able to claim that REAL VWs don't need antifreezeturbobaja wrote:...I think the copper piping to plumb water to a heater core would end up being more of an exhaust cooler than an good source of HOT coolant to heat the interior...
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Re: Modified heater boxes for better flow
Just got in from the dunes where we did 2 weeks of hard work in 5 days; so after that and 8 hours of driving I am a little fuzzy.
So, as I think I understand it; you want to cool the exhaust using the copper tubing in order to cool the exhaust to get more expended fuel moving though the heat exchanger portion of the exhaust and, as a possible bi-product of this modification, you may want to use the heat captured (in the liquid?) in the copper line for heating the cab of the car; zat true?
Marc and I did do some PM-ing as I was trying to get clear what was going on and it was interesting to see what Marc both said and had done. In the past there was some interest in using the engine oil, before the cooler, to pre-heat the exhaust and I thought this may be along the same lines but this is a radically different attempt to transfer and use heat.
I think you are going to want to use a liquid rather than just forcing air through the copper as Marc said. Coolant is a carrier/insulater better than heated air as the heated air will cool off quite significantly except in the south and along the equator in the summer months (ask those in the desert about that).
Ford used the principle of heat rises and cool sinks to cool his Model T’s, that is why you often see steam coming from the top of the radiator before they had water pumps to push the liquid though the block and radiator quicker (then came the thermostat). On the old Honda Odyssey’s the flat head design over heated and caused premature engine failure so someone designed, built and sold the liquid cooled head which uses the same principle as the Model T had to circulate water, it works but there are better ways. I’m not sure what they did with the Honda Pilots but they do have a water jacket and liquid cooled head but I don’t know if they have a water pump or not (I don’t think so). They do have a thermostat on the radiator to cool hence circulate the coolant faster. Snowmobiles I think are also similar but I have never had contact with one, just some people who use them.
Some thoughts; unless you force the coolant though the coils you could have problems such as:
The hot water will go to the top of the coils, sit there and maybe even turn into steam,
I think straight tubes will work better although the period of heat exchange will be shorter,
You may not get much coolant circulation because somehow the coolant has to be forced though the coils, I am suspect if the cooler coolant will have enough pressure to do it.
You could run into electrolysis in the copper and the tube will rot like a radiator does,
The material in the tube may be too thick to exchange the cool coolant temp with the heated metal in the exhaust tube.
You would need two radiators, one for each bank of cylinders/heat exchangers which also means, a second fan and thermostat; e.g., one for each radiator.
I am not sure if this is all of it but it is something to think about. I could also be totally wet or full of hot air on this too (pun intended).
Lee
Spelling correction, becomes a different word.
So, as I think I understand it; you want to cool the exhaust using the copper tubing in order to cool the exhaust to get more expended fuel moving though the heat exchanger portion of the exhaust and, as a possible bi-product of this modification, you may want to use the heat captured (in the liquid?) in the copper line for heating the cab of the car; zat true?
Marc and I did do some PM-ing as I was trying to get clear what was going on and it was interesting to see what Marc both said and had done. In the past there was some interest in using the engine oil, before the cooler, to pre-heat the exhaust and I thought this may be along the same lines but this is a radically different attempt to transfer and use heat.
I think you are going to want to use a liquid rather than just forcing air through the copper as Marc said. Coolant is a carrier/insulater better than heated air as the heated air will cool off quite significantly except in the south and along the equator in the summer months (ask those in the desert about that).
Ford used the principle of heat rises and cool sinks to cool his Model T’s, that is why you often see steam coming from the top of the radiator before they had water pumps to push the liquid though the block and radiator quicker (then came the thermostat). On the old Honda Odyssey’s the flat head design over heated and caused premature engine failure so someone designed, built and sold the liquid cooled head which uses the same principle as the Model T had to circulate water, it works but there are better ways. I’m not sure what they did with the Honda Pilots but they do have a water jacket and liquid cooled head but I don’t know if they have a water pump or not (I don’t think so). They do have a thermostat on the radiator to cool hence circulate the coolant faster. Snowmobiles I think are also similar but I have never had contact with one, just some people who use them.
Some thoughts; unless you force the coolant though the coils you could have problems such as:
The hot water will go to the top of the coils, sit there and maybe even turn into steam,
I think straight tubes will work better although the period of heat exchange will be shorter,
You may not get much coolant circulation because somehow the coolant has to be forced though the coils, I am suspect if the cooler coolant will have enough pressure to do it.
You could run into electrolysis in the copper and the tube will rot like a radiator does,
The material in the tube may be too thick to exchange the cool coolant temp with the heated metal in the exhaust tube.
You would need two radiators, one for each bank of cylinders/heat exchangers which also means, a second fan and thermostat; e.g., one for each radiator.
I am not sure if this is all of it but it is something to think about. I could also be totally wet or full of hot air on this too (pun intended).
Lee
Spelling correction, becomes a different word.
Last edited by Ol'fogasaurus on Sat Sep 03, 2011 8:45 pm, edited 1 time in total.
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Re: Modified heater boxes for better flow
Guys, I fully realise that the liquid heat system would absolutely require a water pump for proper operation.
I will stick to the system that I have (forced recirc) or simply go gas heat.
The downside to the system that I have, is that it has pointed out that my driver side heater channel is probably in need of replacement. But that will be another thread all together.
I was just exercising the brain.
Since I live in Dallas, I only need heat for a couple of months, and lots of it for just a week or two total.
I should add that I have noticed that I could do more by simply replacing door, hood, and window seals, than by actually upgrading the heating system.
I will stick to the system that I have (forced recirc) or simply go gas heat.
The downside to the system that I have, is that it has pointed out that my driver side heater channel is probably in need of replacement. But that will be another thread all together.
I was just exercising the brain.
Since I live in Dallas, I only need heat for a couple of months, and lots of it for just a week or two total.
I should add that I have noticed that I could do more by simply replacing door, hood, and window seals, than by actually upgrading the heating system.
- Marc
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Re: Modified heater boxes for better flow
So true. I've found that just not having the trunklid latched tightly causes frigid air to blow in everywhere it can at the dashboard (around the fusebox, etc.)helowrench wrote:...I should add that I have noticed that I could do more by simply replacing door, hood, and window seals, than by actually upgrading the heating system...
With a poorly-fitting hood, the entire trunk volume is under pressure at speed and it's almost impossible to stop air from getting into the cab from there.
During the coldest days of last winter I used a portable heated seat cushion. Doesn't do anything for your face and fingers, but it's surprising how "less chilled" you feel when the small of your back is warm...we'll be putting real heated seats from an i300 Lexus in the current project car.
Another tactic I've used in colder climates is a 110V "milk barn" heater on a timer to start warming the car's interior a couple hours before departure.
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Re: Modified heater boxes for better flow
The aircraft spruce website shows nice heat ex hangers that install into straight runs of tubing. They can be installed right before the muffler, after the 4->1 collector. They have pipe to air, and pipe to liquid units. The air units work just like the vw heater boxes.
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Re: Modified heater boxes for better flow
Do you have a link for this? I looked around their site in the exhaust and then the heater section and could not find it. Did find some cool 12v heaters, one that only draws about 30 amps and puts out 1764 BTU's. http://www.aircraftspruce.com/catalog/e ... 123000.php there are more that draw more amps, anybody know how many BTU's it would take to heat a bug cabin when it is about 30 deg out?Steve Arndt wrote:The aircraft spruce website shows nice heat ex hangers that install into straight runs of tubing. They can be installed right before the muffler, after the 4->1 collector. They have pipe to air, and pipe to liquid units. The air units work just like the vw heater boxes.
Two Wrongs Don't Make A Right...... But Three Lefts Do!
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- Clatter
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Re: Modified heater boxes for better flow
If you look at a cross-section of the factory German heater boxes, you will see they have a larger tube inside the heat sink.
There was a cross-section picture of the whole motor that showed it.
Can't find the picture, but many of you have seen it.
Marc used it has his avatar years ago, right?
-Edit- Here's one...
http://www.vwfusca.net/wp-content/uploa ... iagram.jpg
Look at the oblong, wavy-edged profile of the inner tube - there to increase surface area.
Because the exhaust pipe diameter gets bigger as it flows through the sink,
it might actually be big enough for your 40 or 42 exhaust valve.
It's the mounting flange, and pipes in and out of the sink area that are the choke point.
If you simply add bigger pipes to each end of the factory heat sink, viola!
Heat, and exhaust flow.
Or am i missing something here?
There was a cross-section picture of the whole motor that showed it.
Can't find the picture, but many of you have seen it.
Marc used it has his avatar years ago, right?
-Edit- Here's one...
http://www.vwfusca.net/wp-content/uploa ... iagram.jpg
Look at the oblong, wavy-edged profile of the inner tube - there to increase surface area.
Because the exhaust pipe diameter gets bigger as it flows through the sink,
it might actually be big enough for your 40 or 42 exhaust valve.
It's the mounting flange, and pipes in and out of the sink area that are the choke point.
If you simply add bigger pipes to each end of the factory heat sink, viola!
Heat, and exhaust flow.
Or am i missing something here?
Speedier than a Fasting Bullet!
Beginners' how-to Type 4 build thread ---> http://shoptalkforums.com/viewtopic.php?f=1&t=145853
Beginners' how-to Type 4 build thread ---> http://shoptalkforums.com/viewtopic.php?f=1&t=145853
- Dangermouse
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Re: Modified heater boxes for better flow
Had these sitting in my computer if they're any help.
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Re: Modified heater boxes for better flow
Hey, thats pretty cool!
Two Wrongs Don't Make A Right...... But Three Lefts Do!