Radiator recommendation?

[Johnnypig]

I am interested in cooling my Listeroid , a 12/1 Powerline with an auto radiator / fan setup. Does anyone have any recommendations regarding what to look for at the junkyard? i.e. a specific auto model radiator that has worked well for you. Any other tips with regard to doing this that might be helpful would also be appreciated. It will be running a 7.5 kw st head. Tried the search function but came up blank.
Thanks,
      JP

[38ac]

Radiator you choose needs to be vertical flow. Because of the way the car radiators are designed (for a pump) you need a surge tank above to make sure the coolant level is always above the top hose. Did one that way but wont be doing any others. John Deere made boo coo thousands of a cute little 2 cylinder powerunit called an LUC. Radiators are made for the thermosyphon systems with big tank above the top neck and made of real copper. I had no troubles finding a good one for $75. Adapting the hoses down to 1" can be Done many ways.

Here is one on a DES 6/1

[LowGear]

It depends on how much of an "Art Project" kind of person you are.  I've dreamed of a "T" brass radiator or one of those welded aluminum replacement units.  Of course the method of air circulation will be a big factor in sizing.

I've heard that some people just use a barrel of water - can you believe that?

Casey

[rleonard]

Vertical flow and a large tank at the top.  A Ford 8N tractor radiator works and are available on ebay.

Bob

[t19]

I have a Caravan rad... it was $25 at the wrecker

It works with an electric fan in the summer to cool it off....

I wish I had gotten a Truck rad, bigger, less chance of me forgetting the power to the fan and less chance of things getting really hot...

But ... this little one works well

[Tom]

As T19 said, a modern cross-flow radiator can be used, the top inlet just has to be kept submerged. One easy way to do that is by removing the inner seal on a radiator cap and placing an overflow bottle, with a bottom drain, above the level of the radiator. Removing the inner seal of the radiator cap will make it a non-pressurized system. If your generating 120vac I would think an attic gable vent fan with a thermostatic switch would be a good way to go. If you take the switch and mount it to the bottom radiator hose the fan will turn on when the water is being returned to the engine gets hot.

[xyzer]

I used a crossflow off of a Saturn mounted to be a vertical flow with a large reservoir above it all. The fan has been for show and never required. Outside a slight breeze will keep it cool....The tilt will also help get rid of the heat...

[12 gauge]

xyzer, how long does it take before the bottom of your cylinder is up to temp?  I assume you have a thermostat in the head?  That was a problem I had when starting out with thermo syphon and a water tank, which I don't recommend if you want proper operating temperature.  Love your engines, thanks for sharing them.

Johnnypig,  I used a 1951 Cadillac radiator, but you can make almost anything work.  I wanted my engine to come up to temp quickly and uniformly so I plumbed a loop from head outlet to bottom of cylinder inlet with a hydronic circulating pump in the loop.  A "T" at the top of the loop has a thermostat in it and opens when the loop is hot enough, to send some water to the top of the radiator.  The bottom of the radiator is connected to a "T" at the bottom of the loop.  The engine will come up to temp from top to bottom in about 20 minutes and I'm hoping that operating at the right temp will help it last a long time.  I have a small fan on the radiator and it seems like more than enough.  I'm thinking of trying a computer fan, it may be enough.  That's my $.02 worth, best luck with your project.
Ron

[ronmar]

Yep, a crossflow can be used for thermosiphon IF rotated 90 degrees to make it a vertical flow. You MUST have near vertical for thermosiphon to work.  IF the rad is oriented horizontal, you MUST have a water pump to circulate coolant.

Then you need to add whatever fittings are necessary to be able to purge all the air from the top.  This may include a fitting added to the former side tank turned top tank to bleed off ALL the air and insure adequate water volume remains above the highest point in the plumbing...

As for size, with forced electric airflow, the rad really dosn't need to be all that large for 12HP.  Have any lawnmower suppliers in your area?  Go look at a large commercial water cooled lawnmower, say 26-35 HP.  They are forced air and not very large.  I think something out of a small 4 cylinder car could be made to work nicely...  In fact, you will probably want a fan control switch to allow it to get up to temp/not overcool.  The beauty of the rad being a little too large is that you can always block off some of the surface area to taylor the ammount of cooling to match your heat input from the engine...  Same thing big rigs do with the zip/snap-up jackets over the radiator in the winter time.  

[BruceM]

I have the setup Ronmar and Tom suggest- a side flow radiator turned to become vertical flow, with an air bleed hose fitting soldered to the new high point (former side). This air bleed hose goes up and into the top of the reservoir tank.  The bottom of the reservoir tank goes to the radiator filler neck fitting, and the cap is modified to be zero pressure.

I use induced draft from the exhaust venting into 8" galvanized duct to pull air through the radiator.  6x12" of exposed radiator area is more than adequate for my 6/1.  My radiator is a bargain monster, and I will someday replace it with something much smaller...

A geo metro radiator or even a larger  heater core would be a good match - smaller radiator means less coolant to heat up to get up to operating temperature faster.

[Johnnypig]

Thank you all for your suggestions ...very helpful, will try to post pics once its up and going

[ronmar]

A geo metro radiator or even a larger  heater core would be a good match - smaller radiator means less coolant to heat up to get up to operating temperature faster.

Bruce reminded me of one other thing to think about if contemplating thermosiphon.  IMO, the ideal setup has nearly as much coolant in the radiator as is in the head/cylinder.  I ran into thermosiphon issues initially with my heat exchanger.  Very small unit with very low volume.  Even with a perfect cooling water source on the secondary, the mass of chilled coolant was very small compared to the mass in the engine, and it just didn't flow very well. I liken it to a fat kid and a skinny kid on a teeter-totter, it just dosn't work well:)  I wound up having to place the heatex  nearly 30" above the engine to put enough volume up in the cooling system to approach balance in the system. 

I have right at 2 gallons total coolant in my 6/1.  I would not reccomend any less coolant than this, as I am pretty sure that is the bare minimum required to achieve a balanced thermosiphon flow that is fast enough to keep the engine cool, at least in a 6/1...  Along that line I don't think a radiator any smaller than that from a geo or a honda CRX would work very well.  Not because it cannot remove the heat, but because of the lack of volume.  If a radiator smaller than that is used, like my heatex, it would probably need to be elevated higher to make it flow better... 

[xyzer]

xyzer, how long does it take before the bottom of your cylinder is up to temp?  I assume you have a thermostat in the head?  That was a problem I had when starting out with thermo syphon and a water tank, which I don't recommend if you want proper operating temperature.  Love your engines, thanks for sharing them.

30 minutes give or take...

oid-2 with a metro radiator. Presently it has a the original 12 volt fan with an adjustable thermostat switch. It still take a dead calm warm day to need the fan. I have a pulley built for between the flywheel and the case to run a small fan like some of the originals do.....need time to finish it off.

 

[BruceM]

I've got lots of vertical to the radiator, so shouldn't have trouble with a heater core or motorcycle radiator...but the geo metro radiator is cheaper, so someday that's what I'll probably switch to.





That's a very nice looking setup with the geo rad., Dave.

[12 gauge]

I see the value of more vertical distance in the water column to make thermo syphon work better.  Still, the inlet has to be getting somewhat colder water that warms as it rises toward the head.  Maybe that just doesn't matter with these engines, either. 

Bruce, your power house must be on the cutting edge of lister development, looks great.

Ron