It gets cold here in Northern California often in the moorning. So I decided to build a liquid heater. First, I spent some time measuring the inside of the fresh air box. I figured I could fit a core 11x6 maximum. my son and I spent several hours at the local Pick and Pull junk yard. I settled on a Transmission cooler from a late model Ford Truck. Cooler measures 10x6.

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I quick placement and I realize I need to cut! The water dam for the fan must be cut down. Make sure not to cut all of it so that it will still keep some water off the motor.

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The finish cut to the dam. Ready for the lid? Not yet.

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So now the core fits on the fan base.

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The top must be shaved down too. Leave as much as possible for the rain cover. I don't park or drive in the rain but weather happens.

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Now the core fits into the air box. Need to test fit in the car and seal the box.

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In the car! Just need to plumb hoses to the rear. I picked up a Volkswagen rabbt heater valve to control the water. I will use the red handle to open it. The diverter valve will not be needed fo the stock heater, so I will juggle the heater cables around to suit.

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I added a petcock to vent out air.

now to finish and try it...

i was recently looking at doing something very similar to that. i was going to look for a heater core instead of a tranny cooler but very simialar idea. looks good.

Mike,
Thanks for sharing. Since I'm a DYI kind of guy, I'll make one too....thanks for the leg work. I''ll be especially interested how you tap into the water system and how that effects air in the system. I would think since it will be the highest point of the car, it might be a nice way (with the heater valve on) to bleed the system.

PS Renegade and Marks914 both make these units similar to yours.
Way to go,
Mark

I did the same thing a few years back while we lived in Colorado. It works great. I used a Ford heater core though and the water lines exit on the passenger side of the box. I don't know if those small fittings will give you the flow you need.
It does create another high spot in the system so a bleeder is required. I used a "T" in the hoses to and from the radiator.
The Ford core I used has the same size inlet and outlet, theory says that one should be greater than the other to give better draw, but this worked fine.
MoPar makes an inline control valve, I had one on a Dodge truck which is where I got the idea. I hooked the Red lever on the dash to the Dodge valve.
The Ford core is much thicker, so I had to make a new top for the fresh air box. If anyone's interested I can go out and snap a picture.

Mike,

I had to replace my vent box in my V8 car as the drain holes fittings where broken. George at AA told me that some of the V8 guys where putting the heater cores in the air vent boxes. Thanks for showing me just how you did that. As I in Los Angeles I will not need heat it but is good to see how it is done. Thanks

Bob

Bruce I would be interested in seeing some pics. Kq6dxn has a nice design. But I would like to take a look at a couple of different set ups and see what might work best for me. I have a 3.3 subie 6 I'm installing and I will need some heat.
Thanks,
Rick

I was looking for a forumpost like this a while ago, so thanks for posting.
I see the 914 also uses a Behr unit. The one I've just fixed in my daily driver, Mercedes w114 coupe, is also a Behr unit.

For the people that want to take this conversion a step further. It looks pretty easy to drop on a more powerfull DC motor. ( Dropped a BMW blowermotor in the Benz).
Why? Because you can ;-)

Just to add in some data, when I had an 86 Ford Bronco II I replaced the heater core in it and it was small and looked like it would fit perfect in this location. I had a similar idea for when I do a 3.0 Suby 6 some day.

Here is a link at NAPA:
http://www.napaonline.com/Search/Detail.as...6+50028+2028008

Dimensions:
Heater Core Height : 8"
Heater Core Hose Size : 5/8"
Heater Core Length : 6"
Heater Core Width : 2"

They are pretty cheap

The core I used has 3/8 NPT fittings and I'm using 1/2 inch hose barbs. Ideally this would be 5/8 hose barbs. The tranny cooler has more hot water surface area than a standard heater core, I think the 1/2 will give enough hot water. Anything is better than cold air!

thats exactly what I was going to do about 5 years ago!! Looks like it will work great!!!

Two of my favorites Dr. E
Pretty and cheap

Nice work. I just wish I had seen this (thought about it) a year ago before I fabbed a heater to fit in the front trunk. It's ducted out through the fenders to the cabin. It'll probably work once I get the car finished but it was an absolute fabrication/installation nightmare. This is the way to go.

Tom

Mike,

Can you be more specific on the year/application of that late Ford truck trans cooler? It looks like the best fit I've seen so far. Also, what are the fittings, O-ring, NPT, flare?

As for heater cores, I scoured the parts books and really didn't find an optimal fit. It's the core thickness as I recall being the biggest issue. I never considered looking at oil coolers at the time, but that's a great idea.

Thanks,

Andys

Mike,
How does this NAPA part compare to the Ford part you used. Now that you've done the fab work, would you have done it differently?

How thick is that Ford core?
Thanks,Mark

The Ford was a 1990's F-150. This cooler uses 3/8 NPT fittings. I did see some that use 1/4 flair fittings. This cooler is about 1 inch thick.

I think this one is too thick. You would need to remove all of the rain shield to get it to fit. The plumbing looks like it might be a problem too. The one I have is 10x6x1 and almost fits perfectly. The plumbing is easy and right between the air box and gas tank. The design of the core I have is a "cross flow" and made for maximum oil cooling. I think it will conduct heat really well. I paid $25 at the junk yard and it is is perfect condition. I had to run some carb cleaner through it to get all the tranny fluid out. I flushed it with water and it looks brand new.
If you want to make a new plenum from fiberglass, a bigger core can fit but it would be much more fab work. I spent 2 hours making this and 24 hours waiting for the mastic to cure to seal the housing. I just ordered some high performance, insulated heater hose in bulk. I'm thinking of running it in the factory heater tube in the long. I'm going to install some new aluminum flex hose to insulate it further where it comes up through the floor. I think this will seal excess heat out of the cabin.

Hi Mike --

Great post! I am just now trying to figure out the heating system for my Suby conversion, so the timing is perfect.

Why run the hoses through the heater tubes? Why not just tap into the "in" side of the radiator hose?

Geoff

My radiator runs super cool, too cool. And... I don't have any air in the radiator, so why induce it by cutting into it. When I drive the car, the temp never gets above 150 unless I'm stopped long enough. I have the heater connections on the engine already (although plugged). So if I use the factory heater connection, I only have to purge air out of the heater system. Also, I considered using the radiator but there was no really clean way th get hoses up the the air box. I could drill holes and run under the gas tank, but that would heat up the fuel. The tube in the long is already there doing nothing. It was designed for heat. There is not really any sharp edges in there. I also could have run the lines similar to the factory A/C lines. But then the hoses are in the wheel wells and more holes have to be drilled.

Hi Mike,

Kewl, let me know how it goes. I'm not too far away -- and I appreciate the fiberglass rear trunk lid -- so PM me if I can help you with the install.

Geoff

Yup,
we made about 30 of these over the past few years,. I like to use a 94 Mustang core. thin and both tubes come out theend.
Mark

Ford core is the way to go.... I just don't think you will flow enough water with the small brass fittings.
I wish I could remember more about how I fashoned the inside for the rain water, I did this so many year ago, I can't get a pic of the inside without takeing it apart. The idea is though that the core must be covered so water will drain and not get sucked through the core.
This isn't a very good picture, had to use my cellphone, can't find the camera! the aluminum cover has a bulge you can't see that I used a hamer and a bag to create. And the first fitting in the line is a plastic filler "T" that I put a schrader valve in to vent the system. The second fitting is the mopar valve that is hooked the red lever on the dash.
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Mike, I understand your logic with wanting to run hoses to the engine, but I would like to tap into the radiator since mine always runs between 180-190. My biggest concern is how to run the hoses and the introduction of a "high spot" in the system.

So if a valve is inserted in the high spot, would it be a good way to bleed the entire system with the heater on? This may be a dumb question, but how do you know all the air is out of the system?

The number one reason I know all the air is out, because it runs too cool. If air was trapped in the system it would run hotter. I also have a steep driveway. I have parked both directions and opened the high spots looking for air. I have an aluminum vessel for the hoses to pass through at the engine bay. This is the rear high spot. My radiator leans back and has a petcock at the highest spot in front.

It would not be hard to tap into the radiator hoses with a T, but you then have to re-bleed the system. and recover all that glycol in the system. Ethelene Glycol is hazardous to the environment.

As part of my job, We use liquid monitoring equipment. To purge the air out of our system we use a vacuum pump pulling through a vessel. The system is sealed except for the vacuum port. the vessel connects between the vac pump and vac port. this keeps any liquid out of the pump. if the system is sealed, the vac pump will pull all the air to the vessel. This technique can be used for purgng air from our cooling systems too.

http://www.amazon.com/Koolatron-12v-Auto-H...r/dp/B0001Z2S4K

cant use it in a 4 cly car because it draws too many amps...

I found this heating system much easier to install:

kq6dxn You must think a lot like myself cause this is what i started doing. although i started with a heater core from a subaru legacy. Where did you get that tranny cooler?

Junk yard. Ford F150

I don't have pics at the moment. My previous Rotary conversion car had a nice system setup. It was built & bolted to the engine bar right next to the motor. Easy to have the lines run from the motor ports. Then introduced the heat the way the heat exchangers do. Had dual hoses running to each side just like you would for HE. Seemed like a pretty good way to go if you have the space in your engine bay. Which most of us with watercooled motor's do

Looked up my thread & got pics

If you have an inkling to run an under dash AC unit, they are avaiable in heat/cool, so they have a heater core in the unit. All it needs are the lines. I'm installing this type of unit in my car; It has a defrost diverter valve which I plan to duct into the heat ducts on either side on the cabin (which may be a real challenge, but that's what I'm planning on).

Andys

Jaime, Your setup is awesome but bulky. I could not fit your rotary system in my rotary conversion. I bet it works great though... My system works pretty good too. In fact, I need to figure out how to shut if off better during the summer months.

I missed this discussion last year when I was looking for a good heating solution.
Biggest thing I would like is defrost.
I came up with a pick your part heater core from, I think, a Kia.
I remember it fit well in the fresh air box and took a photo before aborting the idea and made a heat exchange box for the core in the engine compartment.
I used one 914 blower that pushed the hot air through the longs. The coolant lines came directly from the Subaru ports.
The heater lever opened a coolant valve from a Honda at the same time it opened the flapper boxes.

I was not happy with this setup. My windshield is not fully defrosted by the time I get home from work. Sure it is only 2 miles but the type IV did the job fine.
For 1 I don't feel a single 914 blower has the capacity I need.
I am not sure now but isn't some of the type IV cooling fan air directed to the 914 heat exchangers? If so I am missing a big fan.
I also feel the 914 heat exchange system would generate a lot of hot air faster than heating coolant first. On top of all this I am pushing the hot air a long way through cool long tubes.

I am thinking about going back to the fresh air box idea but I was not sure how to get good hot coolant flow to the core.
I now think a smaller fitting to the hot radiator line, larger to the cool line would create a vacuum? Or better if I could send the larger core line back to the hot to be cooled more by the radiator?
Mark and Bruce may be able to answer some of my questions on this method. Is there any function lost by putting the core in the fresh air box? I think of the fresh air fan mostly for the dash vents, not so much for the defrost vents, do the vents de vert for defrosting well? I was also worried about having the fan motor down stream of the heat exchange.

JRust has the same as I, I wonder if he is getting fast hot air with his system.
I'm thinking if I did that off by Turbo down tube I would get some hot air fast.
Again I find it easier to suck the hot air through the 914 blower and don't think it would hold up to the heat. So I am tossed between the fresh air box or Turbo down tube...

I'm using one of these and I'm a satisfied customer. The airflow dynamics work well and the cabin is toasty. The principal of the heatercore location is sound for heat distribution.

Here is the system I have now and I am ready to pull it out.
My motor runs cool and I need more heat.

Care to sell that?

You know what they say about one mans trash...
Soon as i come up with something that works better for me, its yours.

KG6 mike
Maybe if you use a coolant shutoff valve before and after your heat exchange.

I am blindly moving forward with this.
I picked up a 3 or 4 speed blower out of a 924, 944 or 928?
It moves a lot more air.
I am now relocating everything in order to make room for it.

In order to get fast heat, I keep going back to the exhaust heat exchanger.
I picked up some perf sheet thinking I could attach it to the header x-tube and make a shroud for air to pass through.
Not sure where I am going with this yet???

Even running the heat on high with the exchanger in the fresh air box while living in Colorado I never had a problem with the system holding up to the heat.

I used a simple "T" in each of the lines running under the car to the radiator the heater core, one in, one out. I also used a high flow thermostat. It has openings around the plunger that always allows some flow.

It is always easier for the car to draw water through both the radiator and the heat exchanger than it is to just draw through the radiator. Heat and defrost is always available through the dash controls.

Why not find a way to retrofit the heater box and accumulator from a modern car under the dash. This would give you heat, defrost, AC, and the multi speed blower motor. I was looking over my new car and it looks like the dash area is similar in size to the dash area on my CRX.

It would be great to find something to rerofit from a small production car.

I bought an under dash AC evaporator with heat and defrost from HRA for my V8 conversion car, so all those things you mention are there. Plumbing in the ducting will be trick however.

Andys

Bruce,
Just how hot and fast do you get heat?
Maybe compared to an air cooled 914.
I would think with one fan you have much less flow.
I am convinced there is no meltdown problem in your system.
What can't determine is how hot and fast this system would work with my WRX.
I was working on the front of my car the other day, with it running, and it seemed like 5 min before the fans turned on. Seems it takes a lot of time to heat coolant where I think the manifold would go over 300 deg very fast.

Brett,
This blower is like the ones in some westy vans. Thinking if it will heat a van...
I looked at a lot of mimi van heating systems. I saw one in maybe a Astro or Aerostar van that looked like the complete unit would fit under the passenger foot bolster. It also had a very small heat exchanger. Personally I don't want any more in the passenger compartment.

"Ruby"
Just how hot and fast do you get heat? Maybe compared to an air cooled 914.
Part of the problem with the teener heat is that the blower in the engine bay has to run the warm air all they way from the back through the cold longs and by the time it gets to the distrubition boxes it's really not too warm. I'm not sure about your subie, but most water cooled engines take a hose off the manifold before the thermostat so it will have constant flow and not have to wait for the "stat" to open.

I would think with one fan you have much less flow.
With the heat exchanger right at in the airbox, you might have less flow, I don't remember how the heat controls boxes worked with head coming from the back, I have those capped, now the heat only travels a very short distance before coming out the defroster vents or under the dash.

I am convened there is no meltdown problem in your system.
What can't determine is how hot and fast this system would work with my WRX.
I was working on the front of my car the other day, with it running, and it seemed like 5 min before the fans turned on. Seems it takes a lot of time to heat coolant where I think the manifold would go over 300 deg very fast.
As I mentioned above,I'm not familiar with the WRX but on most of the water cooled engine heating systems water is available before it gets to the thermostat. The Chevy has a water cooled intake system and there is a place there that a water line will go to the heating system allowing water to flow regardless of whether the thermostat is open or not. This allows heat pretty quickly. I happen to have a thermostat the has by holes around the thermostat plunger that allows a constant flow which seems to help with the cooling with the long run hoses also. I hope all this helps.

Don't get me wrong, I am not bashing the heat exchange in the fresh air box.
I think it is a great location, best if I can make it work for me.
So, I did some interesting test.

I did a little test of my FI 2.0 type IV 914 with a thermometer on my defrost duct on a 68 degree morning.
I turned the fresh air vent and fan all the way off with the other levers directed for full heat to the defrost ducts only.
68 degree at start up
80 after one min.
90 after 2
102 after 3
112 after 4 and
126 after 5

Next day with the 914 fresh air vent and fan on full with the other levers directed for full heat to the defrost ducts only.
64 Deg. at start up
62 after one min.
64 after 2
66 after 3
68 after 4 and
71 after 5
74 after 6
76 after 7
then I turned the fresh air fan off and the temp went up to 140 Deg in the next 2 minutes.

I makeshift, reinstalled the WRX 914, Kia heat exchanger set up and tested the air directly out of the EPS lined heat exchange box port with the 914 blower pushing the air. No air traveling through the cold longs yet.
I think it is also note worthy that I have 20' of 1.25 radiator hose = 2 extra gal of coolant.
This system is also hooked up to the OEM heater ports not tapped into the radiator hose.

64 Deg. @ start up
66 @ 1 min.
78 @ 2 min.
88 @ 3 min.
93 @ 4 min.
97 @ 5 min.
98 @ 6 min.
and 98 @ 7 min.

I did the same in my Toyota Tacoma
70 Deg. at start up
68 after one min.
70 after 2
76 after 3
86 after 4
94 after 5
100 after 6
104 after 7
110 after 8 min.

Wish I could start my car to give you some readings, but it's not running. I would imagine it would be real close to what ever the operating temp of the engine is as temp drop would be at a minimum.

Anyone else have a, running, heated, conversion and a thermometer?
I would like to know what others are getting out of different setups.