Another radiator question.

As I've mentioned, I'm going to mount the radiator on my '39 Dodge truck in the bed, and need some advice on mounting it. First some facts. The engine is a 394 Olds with some mild mods, running through a 4 speed hydro. The bed is open in the front (against the cab) and the metal tonneau cover is punched full of 244 louvers. I am also going to either louver or holesaw lots of holes in the tailgate. Point is, airflow should be no problem. Also, running the water through some piping that is about 1.5 inches in diameter all the way to the rear and back again should add some capacity and additional cooling.

I have lots of room in the bed, it is about 42 inches wide x 42 long x 18 high, so I can get a big radiator back there. I am thinking one of the 19 x 31 aluminum universal crossflow ones. I also have room for a 10 gallon tank and battery, with room left over.

Here is my dilema: I can mount the radiator one of two ways.........

1) Standing up like most radiator but back against the tailgate with one or two electric fans pushing air through the radiator and venting out through the holes I punch in the tailgate.

or,

2) Laying flat down on top of the rear kickup with the inlet and outlet pointing down with the hoses coming into the bottom. In this position the fan(s) would be on top, pulling the air up through the radiator and out through the louvered tonneau cover.

I actually prefer the second option as it would make mounting the gas tank easier, but my question is, will a radiator properly distribute and flow water if it is laid flat? Airflow would be just as good IMO, and I plan on building some sort of airdam under the car to scoop up air when underway. My opinion is that a radiator doesn't care how it is laid, it will still fill up with water and transfer heat just the same. I even think I have seen some exotic cars with radiators either laid flat or on a shallow incline.

Here is a picture (but not a good one) of the area I will be installing it in. Anyone have any thoughts on this??? :)

Don

O.K. buddy, you asked for it :LOL: It doesn't know or care, all it wants is the correct water flow threw it and some clean air going threw it. So how are you going to move all that water,stock water pump?
Ken

That is something I have to figure out too. I think the stock water pump moves a ton of water, but maybe I will have to add an electric booster pump in the middle to suppliment it. Not sure. I am going to add one of those in line water fills with a cap on it so I can put coolant in the radiator, I do know that.

What is your opinion on the flow Ken?

Don

I built a '29 Model A sedan delivery with a Hemi Ford (740 CU.IN.) and had to put two radiators in it. I used a electric pump made for a RV hot water tank. The rear radiator only had an inlet and outlet and a bleeder valve in it. If you do decide to do this it is really not that bad, just some more fabricating. Will you put a small radiator in the front or nothing?
Ken

No radiator in front, only this one in the back. I like the idea of the RV pump. What size hoses go to it? I'm wondering if I really need 1.5 or so hoses to the back or if something like 1 inch will flow enough.

A few years ago there was a T bucket at Turkey Run that had a big blown engine in it, and he had two radiators like you describe. The second one was up against the tailgate, which was cut out and screen put over the holes for cosmetics.

Don

Don,
I don't use thermostats, I just use washers in the thermostat housing. I just adjust the diameter of the hole in the washer to regulate the time the water is in the radiator. So if you go with that theory, you can use a 1" i.d. in your washer and a 1" id. in the radiator hose. If this doesn't make sense I will try again. You know about my writing **)
Ken

I just remembered, some marine engines use a "raw water pump" that is designed to suck water out of the body of water you are in and then the regular water pump becomes a circulating pump. If worst comes to worst I could mount one of these on the crank to boost the flow of water to the back.

Don

Quote:

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Originally Posted by Ken Thurm

Don,
I don't use thermostats, I just use washers in the thermostat housing. I just adjust the diameter of the hole in the washer to regulate the time the water is in the radiator. So if you go with that theory, you can use a 1" i.d. in your washer and a 1" id. in the radiator hose. If this doesn't make sense I will try again. You know about my writing **)
Ken

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No, that makes perfect sense. I even thought of leaving the thermostat out altogether and using nothing that would impede the water flow.

Don

You can do that but if it doesn't stay in the radiator long enough to cool. Remember, the radiator takes the heat out of your water if it isn't restricted to stay long enough it won't cool properly. I would suggest you restrict it with something. Be sure your external pump is designed to move hot water.
Ken

a radiator that would normaly cool the engine your trying to cool would flow approx.26-32 gallons per minute.not sure if you would need an extra pump.I would install a good temp gauge and go from there .as far as the position of the radiator I dont think it would matter alot as stated in the earlier post.as long as it has air moving across the fins.

I agree with you guys, I think the long run alone will drop some heat and I can get the biggest radiator made back there. I might actually have the opposite problem, running too cool. That is a problem I will take though. :)

Glad to see you guys agree that laying it down won't cause the radiator to only partially fill up. My opinion is that the pressure will insure it being filled at all times. I like the vent idea Ken, to bleed off air. The radiator will be sort of as high as the top of the engine, so that is where I could bleed it off.

Don

I just found this thread. Here's my two cents...:HMMM: The radiator can be ALMOST flat, but needs just a little tilt (as little as 1/2 inch) so that air can rise to the highest point to be bled off (Obviously, your bleeder has to be at the highest point of the radiator). If it's completely flat, air bubbles can get trapped in various places. If there's air pockets in there, then the coolant isn't touching the metal. The heat is removed from the coolant by transferring to the metal and then being blown off into the ambient air, so air bubbles inside the system are your enemy.:mad:

Back in my stock car racing days we used to use the radiators out of Olds Cutlass Diesels because they had 4-row cores and we thought they were the best thing available. We used a restrictor washer instead of a thermostat. On a really hot night the car would run hot anyway, sometimes 230 degrees. Finally, one time when we had a few extra bucks, we bought a Howe aluminum radiator. We had to put a thermostat in it because we couldn't get it to run hot enough!:eek: :LOL: :LOL:

If you use a 19 x 31 Howe or Afco radiator, it should cool OK with the stock pump. Consider the Pontiac Fiero...;)

J. Robinson has it right on, you'll need to be able to purge the air out. So a slight tilt would allow that to happen. Shouldn't need a second pump though, the DeLoren had a V6 Volvo engine and the rad was up front. Coolant was moved through 1 1/2 inch aluminum tubing with rubber hose elbows, nothing but the engine pump was used. If I remember right, I think they ran two rads, neither one was real big. Long, narrow, and two core aluminum, they didn't have much height to work with, with the sloped wedge nose. I used a tilted rad on the airplane I built, with a petcock on the high end to purge the air. Inlet and outlet were at the same end of the rad, with a divider plate welded in between. The coolant travelled down one half of the rad, across the end tank and back up the other half to the outlet. The amount of air going through the rad, is going to make or break the attempt. I had a small 4 cylinder Chevette rad, but I also had a 6 ft fan up front to suppy the air. :D Sniper

Jim and Sniper........very good points. I was thinking of slightly tilting the radiator, but for space reasons. The bleeding of air thing makes perfect sense, and I will have a radiator shop add a bleeder to the top tank. Honda's have a bleeder on top of the engine, and after working on one if you don't open it until you get no air bubbles, it will overheat. (Don't ask how I know........:o )

The 19 x 31 size is perfect and in fact I have 40 inches width back there to work with. With a 16 inch SPAL fan or maybe two 14 inchers I should have no problem cooling it. The bed cover is punched with 224 louvers and I plan on punching more holes in the tailgate too, so air should be able to move through well.

Sniper, you have given me an excellent idea. I was thinking steel tubing for the pipes going to the rear, but alumimum makes so much more sense. I bet I can pick up some 1.5 and 1.75 locally and it should also dissipate heat better than steel would. Thanks for mentioning that.

Don

If you have access to a dairy supply place, or a larger steel supplier, you could go stainless tube. I had short runs of aluminum on the plane, after a number of years, it did show some corrosion in small spots on the inside of the tube. Even with the antifreeze 50/50 mix. A bonus is, the exhaust shops can bend the stainless with no problems, less joints, less leaks. As a side note. Had one guy make the headers for a Vee Dub powered plane from stainless. Had them tig welded, looked nice when done. Just thinking the piping could fit up nice and tight to the vehicle with the proper bends, would look like they grew there! Sniper

I like your bedsides. Did you roll the bead before the brake?

Thanks. Yep we did. I actually "inherited" that bed in it's entirety. My Son built it for his sedan-turned-roadster pickup, but later on changed his mind and bought a model a bed from Brookville. We had to shorten it and narrow it to fit my truck, but the basics were already done. I even got the metal tonneau cover we built and that he sent out to have 224 louvers punched in it. I made out REAL good dumpster diving that day! :D :D

Here are pictures of it when it was on his roadster.

Don

Yeah, that stainless would look great, especially if you polish it.:D If you can't get it you could use copper plumbing pipe. It would look cool polished also, but would require a clearcoat or constant attention to keep it shiny...:HMMM: :3dSMILE:

Or I could leave the copper to age...........PATINA!!! :D :D

Don

Age? Patina..? Yeah, these aren't wrinkles; it's patina!:LOL: :LOL:

Just a thought Don, would it be possible or feasible to modify the top tank to accept an elbow for the filler and radiator cap? I would think that would eliminate the need for an in line water fill.

That's a good point. I was thinking of going alumimum radiator because I just like them better personally, but a local shop might have trouble modifying aluminum. So maybe in this case a copper one might be better.

Don

And if that wouldn't work maybe a fill tank from a '60's era Ford.

Yep. I used one of those when I built my 289/ Sprite. Haven't seen many of those around in a while though.

Don

Quote:

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Originally Posted by Itoldyouso

That's a good point. I was thinking of going alumimum radiator because I just like them better personally, but a local shop might have trouble modifying aluminum. So maybe in this case a copper one might be better.

Don

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I'm thinking that a good radiator shop shouldn't have trouble welding in an angled filler tube in the original filler location.

They also make a T stat housing with a cap for filling. If that ends up being the highest point in the system it might work.

I came here looking for some tips on running the radiator in the back of my Fiat Topolino and I'll be darned if my buddy Don hasnt asked all the questions I was gonna ask. :D Thanks, that was easy.

I could add one thing I have been looking into. Finned aluminum extrusions. They come in all diameters ID and OD. A 3-5' piece going to and coming from the radiator would add to the cooling. The fins run the legnth of the tubing. There is another kind with fins running around the tube like little disks. You may have seen it on the tube that connects the 2 cylinders of a 2 stage compressor. I prefer the extrusion but I dont think I will add this to the system unless I cant get the cooling needed.

Once again, thanks for the help.
Jim

Hey Don, just something that popped into my mind when I read this thread. I remember decades ago when Bill Thomas was raging with Corvairs, there was a write-up about the car overheating. In the end, they found that without a flat sheetmetal pan under the motor, air would stack up under the motor at road speed and hinder the passage of air blown downward by the blower fan on the motor. They fashioned a pan that closed off the front and sides of the motor, leaving the rear open for blower fan air to exit. The high-pressure road air then slid past the motor and out the back of the car with the fan air.

The way you describe it, you have just the reverse arrangement, pulling air in from the bottom and exhausting it out at the top. Just be aware that you could possibly experience the same scenario, with road air stacking up on top of the louvers. I'm no aerodynamicist, I just wanted to pass this along to you.

I know next to nothing about this business, but what I do know is-----------
I love that truck! Better than the T Bucket, even though I enjoyed that build thread. A laugh a minute, what with some of the comments you got from your (friends). haahaaaa. Can't wait to see it on the road. Regards, Perley

Thanks for bringing this one back from the dead, guys. :3dSMILE: I have sort of stopped temporarily working on the Dodge for a couple of reasons, like I am taking a little breather...... I am enjoying putting money into the bank for a change instead of taking it out..... and finally, I want to help Dan get his car running before I do much more to the Dodge.

However, I did buy an aluminum radiator and held it up against the frame on an angle to see how it would look, and I think it will be fine. I am going to take Richard's suggestion and put some ducting underneath so the air gets directed upward, rather that shooting out the back. That, and a good pusher fan (no room for a puller) should do the trick. I think the fact that I will have about 8 feet of tubing running to and from the radiator should help dissipate some of the heat too. I was also able to fit a pretty big (19 x 29) radiator back there.

Littleman on the HAMB has a similar setup in his model A coupe, and he is running a Hemi with a radiator in the back..........I PM'd him about it, and he said it works fine that way. So, when I get back on it the radiator mounting is one of the first things I have to take care of.

Thanks for helping out everybody.

Don

This is something I have been toying with in my head for a while now. I'm wondering if you would need any restrictors at all, as the extra plumbing is going to add restriction.

Consider running the pipes through the frame. How sweet would that be?

My version: a 45A motorcycle alternator bolted on the harmonic balancer.
A remove ( electric ) pump
no power steering pump or AC pump
Gut the water pump on the motor, and plug the hole.

Volia: an engine on 'life support'. No belts. A simple guard around the harmonic balancer and the rest of the motor can sit 'naked'

It will have people looking twice, because it will look all the world like too much stuff is missing for it to run!

Who makes a '100 amp motorcyle alternator'? My '06 Harley only has a 45 amp charging system. What's going to pump the coolant thru the pipes in the frame?

Mike

Look for inexpensive but excellent pipes from a junkyard Fiero. (engine in back, radiator in front - they had nice long straight runs that tucked up against the frame. As you have found out, you have to tilt the radiator. Alternators can also be run off the driveshaft right in front of the rear end, just don't sit around forever. Good luck.

Quote:

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Originally Posted by Mike52

Who makes a '100 amp motorcyle alternator'? My '06 Harley only has a 45 amp charging system. What's going to pump the coolant thru the pipes in the frame?

Mike

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yeah, you got it right.. 45A is the biggest, but it COSTS $100. Maybe that is where my brain dragged up that #.

Coolant is pumed by the remote located electric water pump.

Don,
Techinspector hit on a good point.
One of the things you need to consider is airflow through the box.
I read that you have the louvers in the tonnuea cover and you want to open up the tailgate with some holes to exhaust the hot air.
As Richard stated you have to watch out for (negative airflow) a high pressure air build up.
This is where the air gets trapped due to more air coming into the area than going out.
A good rule of thumb to evacuate the air properly is a ratio of 3/4 to 1 1/2

In other words for every 3/4 inch opening of intake area you need 1 1/2 inches of opening for it to exhaust properly (positve airflow).

Here is a of pic of of a friend of mines ride who's running two rads.
Took it to Woodward Dream Cruise and never thought twice about it overheating.


http://www.clubhotrod.com/photopost/...icture_037.jpg

You can see the holes for exhausting the radiator in the deck lid.
http://www.clubhotrod.com/photopost/...icture_038.jpg