[plum-crazy]

The cooling power is better in an aluminium radiator?
I read about be cool units, 3" thick, 26" width and 19" height, they are talking about 700hp max with electric fan.
Any recommendation about it?

[dave-r]

They are lighter. Not sure if they are better.

Used on modern cars because of the cost of copper/brass.

Main problem is that black radiates (or absorbs) heat better than anything. Silver and white radiate heat the least efficiently.

Switching to a Be-Cool radiator did not cure an overheating problem I had. In fact it made no difference at all either way. I cured that problem in other ways.

I have since painted the front of my be-cool radiator black with correct automotive radiator paint. Just to see if that makes a difference to cooling.

My "bolt-in" Be-Cool had to have the mounting brackets cut about and re-drilled to fit.

[fbernard]

Also, if you're wondering about the price difference between BeCool and other brands (AFCO, Northern), I recently learned that the BeCool units are brazed/welded, whereas most others are glued (core to water boxes). I have no problems with my glued radiator though.

A well rebuilt original cools as well as an aluminum unit. I have a 22" rebuilt (with truck 3-row core) in my convertible (with a 440-6). When I installed it, I could be stuck in traffic and stay cool, something that was impossible before the rebuild. That radiator was meant for a 383, yet it works perfectly.

The aluminum ones are good if :
- you need a bigger radiator,
- you need a lighter radiator,
- you plan on using electric fans and a water pump.

I have an aluminum radiator in the hardtop (The original 35-year old 26' radiator had a hard time cooling the 496. Bought a 31" wide Northern, sold as a Summit brand unit - fits very tightly between the front frame rails).
A lot of fabrication was needed to install it (but there are some bolt-in units, if you know the American meaning of "bolt-in"). A friend of mine has a bolt-in unit (Jeg's brand, most probably a Northern too), it took us less than a day to fit it.

I installed the radiator with the Mopar viscous fan I had before, with no shroud. It worked not too bad.
I removed the fan and installed electric fans (2x10" duals) on an aluminum shroud with a FlexALite controller (crap). It started to heat a little. It was worse in traffic, even with the fans full-on.
I installed an electric water pump (Meziere WP105-HD, with a controller from DC Control) and I can barely see the temp gauge needle going over the thermostat's rated temperature. And I can let it turn after I shut off the engine (that alone was worth it). It's perfect.

Color should not make a noticeable difference.
However, the difference in conductivity (copper = 2x aluminum) means the aluminum radiator needs more flow to cool as well as a copper radiator. Hence the electric pump, which is not related to the speed of the engine. No fan can make the water pump turn faster, which is exactly the problem at idle (engine heats, water flow is low, air flow across the radiator is even lower).

For a street car (even with your Hemi), a new 26' radiator (stock repro) or a rebuilt one should be OK (with shroud and mechanical fan).
But it may not be enough if your engine has a big cam
If you want to go to an aluminum radiator, aim straight for the electric water pump and a good temperature-controlled speed regulator (http://www.dccontrol.com/, I'm using the WP35)
Get a bolt-on unit (mine does not look that well, and was a nightmare to fit). Trial fit it until it works. If you can find someone who can weld aluminum in your area, make brackets for a shroud and an overflow bottle, and have them welded to the radiator .

Using an electric water pump will require that the alternator be relocated.

[dave-r]

Color should not make a noticeable difference.

I think it does. I think it could be 20 or 30% difference.

I think I will have a go at an experiment some time in the future to see if I can show this effect or if there is no difference at all.

[Eddie]

I wonder if anyones ever used this type on the street. I know that the O.E.M. have been using them for sme time, but of course they have engineered a complete system around it. It would help in the "packaging" and avoiding certain components such as the alternator or exhaust, oil pump, water housing, pulleys ect.. www.stewartcomponents.com (The electric water pump module)

[plum-crazy]

Thanks a lot guys.
One year ago I re-made the radiator core and after your comments I will let it in the car.
I currently use a 45cm electric 2 speed fan which flows 4100m3 / hour.
This combination worked well with hot 440, even better with the cooler hemi.
Just wanna change it for the look, cooling improvements, and a friend who wants a buy my original 26", but finally I won't spend the money in it.

I keep founds for the rear end.

[dave-r]

That sounds like a better idea PlumCrazy.

[fbernard]

Color should not make a noticeable difference.

I think it does. I think it could be 20 or 30% difference.


I think I will have a go at an experiment some time in the future to see if I can show this effect or if there is no difference at all.

I agree color (especially black) would have an influence over radiation, but not for convection.


Let's see if I can remember what I learned in school (when I wasn't playing pool).
There are 3 modes of heat transfer :
- Radiation (transfer by light or other electromagnetic wave, like microwaves),
- conduction (transfer by contact between atoms),
- convection (transfer by movement in a fluid).

Color has a (big) influence over radiation.
Radiation is not the heat tranfer method used in a radiator core.

The methods used are conduction (which makes the radiator fins warm, although the fluid only circulates in tubes brazed to the fins) and convection (actually, forced convection, since the air is forced between the fins, either by vehicle speed of by the fan).
Natural convection (which would occur at idle, with no fan) is a poor heat transfer, hence the fan and shroud to artificially maintain some airflow across the radiator.

Paint, however, as any coating, does impede convection.
Some radiator paints claim to have limited effect, or even a positive one.
Even oxidation impedes convection to a degree.


Last, but not least, convection works differently with different materials (water cools better than air, for example), and even better with a phase change. That's why some racers spray gases (CO2, compressed air) on their intercoolers or radiators. That's the principle used in fridges, and that's also why computer processors now use heat pipes.


I found this while looking up Google for "conduction vs radiation radiator" :
http://www.eng-tips.com/viewthread.cfm?qid=61247&page=7
This page has interesting info about cooling.

[dave-r]

I will have a read of that later. But my understanding was that to get effective convection you have to first heat the surface via conduction and heat the air moving over the surface by radiation.
The air then carrys away the heat by convection.

Take a houshold radiator for example. It heats the AIR around it via radiation. The natural process of heating the air causes it to rise and move around the room. Heating the ROOM by convection.

A black painted radiator will heat a room more effectively.

Or look at it another way. The hotter the surface the air moves over, the more heat is transfered to the air.

[fbernard]

Take a houshold radiator for example. It heats the AIR around it via radiation. The natural process of heating the air causes it to rise and move around the room. Heating the ROOM by convection.

A black painted radiator will heat a room more effectively.

Or look at it another way. The hotter the surface the air moves over, the more heat is transfered to the air.

I agree that any black object will absorb radiated heat more than any other color, and its surface heat from the received radiation will be higher, but I'm not sure a black object is better at radiating heat to the outside (it certainly is better at burning your hand if you touch it, but that's just conduction).

[dave-r]

It absorbs and radiates equally well depending on which way around the temperature differential is.

[plum-crazy]

Yesterday I was running the new hemi and I checked the temp on the highway at 185-190.
I use the stock radiator with electric fan.
When car stops on the red lights or trffic jam the temp rises until 210 easyly, and someimes until 225.
The thermostat is a 160º but I ran without thermostat and no difference with temp.
This fan do not have enough power to down the temp.
I try to change this big single fan for twin (38cm) fans to cover all the radiator area.
What do you think about it?
Is better blowing fans or sucking fans?

[dave-r]

Always suck.

The problem is probably NOT the fan though. It will be your voltage.

Mopar alternators are not very good at putting the power out at low rpm. Most of the problem is the poor quality of the wiring (originally and with age) and the contacts in the bulkhead connector (all alternator output goes through one bad connection at the bulkhead to the ammeter).

The result is that you probably do not have enough output from the alternator to power the fan at full speed.

Adjust your idle speed to 900rpm if it is lower. This will raise the alternator output a little. Hook the fan directly to the alternator output via a relay.

Also do an ammeter/bulkhead connector by-pass so that the battery gets full output from the alternator. (See http://www.madelectrical.com/electrical ... uges.shtml )

Another thing would be to fit a smaller pulley on the alternator so that it spins faster. But usually the "trick" thing is to spin it slower to give a few more HP. This is what March pulleys do and why I had problems with my fan.

[fbernard]

Dave is right, the problem starts with the alternator.

I had the same problem with my car last year. I had a mechanical fan (Mopar viscous kit, aluminum fan). It was GREAT. Although not perfect when idling in traffic (some of my friends add a front-mounted push-fan with a manual switch just for this).

The rest of my story is right above, in my post from Aug. 9th.


First make all the wiring work well (big wire between alt and battery +, you should use a terminal block like this one : http://www.jegs.com/webapp/wcs/stores/s ... 2_-1_10409 ).
Install a shroud (or make your own) around your fan. I can see that 1/4th of the core surface of your radiator does not benefit from the fan. You can make a simple shroud with a rectangle of 2cm x 2cm pine and a simple board (dimensions are the radiator core dimensions) One big hole in the center (or off-center if you have water-pump clearance problems) which has the same diameter as the fan blades. Install the fan on it.

Install a relay, and a manual switch in the car. No thermal switch for now.

If, with this setup, you can maintain 160°-175° idling in traffic (let's say 160° in winter, it may creep up next summer), you don't need a bigger radiator. Install a recovery tank, buy or make a better-looking fan shroud, buy a thermal switch (and keep the manual switch as an override).

If that doesn't keep the temperature low enough, you will have to go bigger. That means you'll need a radiator+fan(s)+shroud combo (in that case, try to buy a radiator with a threaded temperature switch socket ; this is way better than the "probe-stuck-between-the-fins" type of sender.

This will take a lot of planning, & measuring.

You can get a complete kit from BeCool. They're pretty expensive though. Try looking up part number 82176 on becool's web site.

Be prepared for quite a few modifications, including transmission cooling lines (that may not end up in the stock locations), check whether the radiator will fit between the frame rails or if you'll have to drill/or trim anything.

It wiil probably be a nightmare to set up everything with the engine in the car.

[drewcrane]

well as an owner of several black cars,i know this from personal experience wit an infared temp sensor my car with a groung temp of 95 degrees was 120, a whith car was 105 roof temp , black gets hotter there fore transfers heat faster if it were pitch black out side ,i would be willing to bet it would be the same. aluminum does in theory transfer heat better ie heads cool to fast , etc.thats my take on it

[drewcrane]

also griffin makes a true bolt in rad. with no trans line mods,a buddie did the fan in front of the rad. and in back, and he ran hotter cause it was too restrictive,also whe ever the indy cars come to town here in denver , the have to double there cooling capacity cause the airdensity is thinner here hense less cooling, my point is this there is alot of adjustment for cooling and especially with a hipo engine, i have cooling issues so this info is perfect for me i will go back to this later, cause i need a little help too!

[plum-crazy]

Thanks guys.
I was looking for this one in summit.
http://store.summitracing.com/partdetai ... toview=sku
This one fits on the full radiator width, 26" and I not using the transmission cooling lines on water radiator, just a separate 15"x12" radiator.
Yesterday definitively I arrived at home (2 km uphill) and once car was into the garage the engine temp rised until 220 and transmission temp until 230 (110ºC)
I think is not good and I need to make the changes before next time I drive the car.

[drewcrane]

there is a set of fans in that sits that 16927 it pulls 400 cfm,s i wonder what kind of draw that is on the electrical system let me know what you end up with.