Still FRICKIN Hot.... what about Aluminium Radiators

[Zderf]

You never know where these threads are going to go. What a hoot to watch....

Anyway, I thought I would supply this informative link regarding the latest in brass radiator technology and its advantages over aluminum:

http://automotive.copper.org/no-flux.htm

Now.. where will this thing go???

Zderf

[Leroy]

The company from Indiana is Afco Racing that makes the alumium raditors not acco, their wed site is AFCORACING.COM great site, alot of tech articles and a great company to do bussiness with. Check them out for great shocks,springs, brakes,etc. No, I do not work for them.
Lee

[DAVID GAGNARD]

Andy FIA;

Take off your radiator cap after the car is fully warmed up and look at the flow in the radiator. Even at idle the water should come out the flues with some force,not just barely trickle like mine was doing. Like I said,I spent a lot of money and time to cure my heating problems and all along the water pump was just turning too slowly to cool the motor down at idle or street driving.

Race cars can get away with the underdrive pulleys cause they are almost always turning a lot of rpms. My car did fine after 2000 rpms.Most of my city driving was that or less..

I did put an underdrive crank pulley on my 95 F-150 and have had no problems,but the truck was ordered with the towing and cooling package. I think with the extra radiator capacity and cooling ,I can "get away" with the underdrive pulley in my normal driving. In city driving the temp gauge barely moves off the normal highway temp reading,my guess is only 5-10 degrees more which I can live with. I do tow quite a bit,either a boat or my car when racing so I could use the little extra I may have gained and the pulley was free from a wrecked 5.0 GT anyway......

David

[chopper]

Richard:

I certainly appreciate your comments, and I completely agree with you that the copper/brass is superior to aluminum in terms of thermal conductivity. If that were the primary consideration, there would be no contest between the two materials as a choice for radiator construction.

Your observation that the smaller tubes represent a higher area/surface ratio is also absolutely correct. Logically though, based on that observation, we should be able to make the radiator more and more efficient by building it with smaller and smaller tubes, hence, the recent trend towards "4-core" radiators. Obviously, there is a point beyond which the smaller tube diameter begins to restrict the coolant flow so much that the efficiency of the radiator begins to suffer. The problem is still essentially one involving three heat transfer reactions; (1) between the engine structure and the coolant, (2) between the coolant and the radiator and (3) between the radiator and the air passing through it. The first transfer may be affected by the choice of coolant and the flow of the coolant through the structure, but for the purposes of this discussion may be considered constant. The second transfer will be affected, as you point out, by the choice of material, as well as the choice of coolant and flow rate. The last is a function of the radiator material and flow rate of the air going through the radiator. I understand that most of the newer radiators have tubes that are oval, not round, oriented with the long axis of the tubes along the centerline of the car. This is an attempt to get a compromise between narrow tubes (for increased surface area), coolant flow capacity (based on tube cross-sectional area), and air flow around and through the tubes and fins.

Zderf's attached article is interesting because this association (The International Copper Association) claims to have addressed one of the biggest problems with the copper/brass radiator, namely the interface between the primary cooling surface (the tubes) and the secondary cooling surface (the fins). Again, as I understand it, current copper/brass radiators use solder to attach the fins to the tubes. Solder is not a good heat conductor, and so the heat transfer between the tubes and the fins is not as efficient as it could be. In fact, when I discussed this with both Griffin and a local specialty radiator shop, both claimed that the aluminum radiators were superior primarily because they braze the fins to the tubes in their aluminum radiators as opposed to soldering them. It will be interesting to see if the proposed copper/brass products live up to their claims. In fact, I believe there is at least some basis to their presentation. When I had my old Triumph Spitfire, I had the radiator re-cored after it developed some pinhole leaks. The shop to which I took it re-cored it with copper and I noticed that the coolant temperature dropped between 5 and 10 degrees F afterwards.

I have noticed that most folks (me included) do not seem to suffer overheating when the car is moving at a reasonable speed, say above 30 mph or so. In my case at least, the problem manifests when I am in slow or stop-and-go traffic. To that end, as David Gagnard points out, the real problem may not be the radiator material but instead may be one of flow rate, either of the coolant through the radiator core or of air through the radiator. I have tried to address the airflow through the radiator by using an upgraded electric fan (sold by ERA) which made a slight improvement in the situation However, a more efficient radiator may tend to reduce the problem by allowing a bit larger margin before overheating occurs. My opinion, FWIW.

[Toivo]

this was touched on briefly by chopper above, but should be stressed...4 row radiators have more surface area, but they are also 'denser' for air to flow through. There is not a 1:1 benefit from additional rows of tubes and in fact the central rows can become heat sinks, holding heat in the radiator. This is another benefit of the copper/brass type radiators, they don't need a lot of tubes.

What I believe is needed is Indium radiators. Excellent thermal properties, but a bit pricey.

[Monster]

Interesting thread. Earlier in this topic the subject of air no being bleed as a possible cause the overheating came up. Having worked on one of the more heat sensitive, overheaters for a number of years the Jaguar, I would like to pass along a few trick we performed to ensure that we had purged all air.

1) Important-Create a high point in the cooling system for air to bleed off to. If there are too many points at the same elevation then air is more likely to get trapped. Lifting the front of the vehicle generally helps depending on where your high point is located.

2) If you have a heater turn it on if it uses a valve to allow water to flow through the core. This again is a common place for air to get trapped.

3) (This part can get a little messy if you get a big air pocket) Fill the system and leave the cap off or loose. Start the engine and let it come up to temp. Air will burp out while the engine is coming up to temp. When the engine reaches temp bring the revs up to 1200-1500 rpm and *hold it there* This will force most remaining air out , *with the engine still at RPM* top up the coolant and tighten the cap.

This process has alway worked for me hope it helps.

Mike "monster"

[Bob In Ct]

Hey Clois:

No matter what % antifreeze you use, or which fan you have, or which radiator you have no car should overheat at 45 MPH in high gear.

Make sure the coolant is flowing through the radiator at sufficient volume. It could be that your water pump is just sending most of the coolant through the heater core and not the radiator. The coolant will take the path of least resistance.


Bob

[Richard Hudgins]

Chopper,

Excellent post and discussion.

A couple of interesting things.

1. F1 cars and FIA sports cars are very sophisticated aerodynamically. They do some serious work in the heat exchanger areas.

A. Flow through a heat exchanger will stall at certain pressures (speeds). This causes "packing" in front of the entrance location to the heat exchangers. (The JBL radiator and nose opening "packs" at about 80 mph with the standard Howe unit) This phenomenon has very significant effects on airlow over, through, and around the body and its attached aerodynamic devices.

B. This is controlled by a number of items such as, annulus shape, annulus size, exchanger core design, and exit design. As one can imagine, it is quite easy to work with everything above with the exception of the exchanger core design.

Secan as well as a number of other firms in the UK make exchanger cores in a great variety of designs to satisfy the pressure gradients required by aero and cooling demands of each circuit and individual vehicle design.

There have been many core designs that would surprise most everyone on this board. Airfoil shaped tubes without fins, airfoil with fins, round small diameter tubes (.040 OD and .025 ID) without fins, (The idea here was to create turbulence around the tubes to gain higher exhange rates, I do not know if that worked) and very high system pressures to allow filling and flow in these tubes. etc, etc.

Ultra high performance heat exhanger design is to me virtually a black art.

All the above said, in a car such as most "Cobra" roadsters, you are looking at a system that is bordering on critical due to the specific heat output of the engines, lack of sufficent cooling area of the heat exchangers, and inadequate airflow at low speeds typically due to insufficent fans.

If you look at most road cars with "normal" engine driven fans, the cfm ratings are in the 4500 area for a small block engine. I think that the best electric fan I have seen is about 2800 cfm. As you can see, this quite a bit below what the OEM boys are doing to make sure your drive in everyday 95 degree LA traffic is something that does not cause concern.

The bottom line here is that cooling system design is a very complex issue and there are no simple answers. The only "fixes" for Cobra type cars that do not cool adequately are:

Heat exchanger area= as big as you can put in there.
Fans= as big as you can put in there.

And make sure the air has a place to exit.

Or, never drive below 55.

[SCOBRAC]

Iron heads.. restrictive R code motor thermostat housing at the expansion tank. It never got over 145 degrees.. I pulled the housing expecting to find no thermostat.. Surprise there was a 160 degree thermostat there all the time. I put in a 180 degree unit.. It runs 160 now.. go figure. I put a digital thermometer in the expansion tank to verify the gauge (something you might consider) and they were pretty close in temp.

It runs a good deal better at 160.. but it still seems low.

Regards,

[a427sc]

Just a few comments on several points.

There is a special funnel, available at most parts stores, to help bleed your system. It replaces the cap, locking on to the filler and providing a resevoir of about a quart. You then run the car until hot, letting the reservoir burble up and down, burping the air. A lot less mess. Cheap at about $20.

A better way to avoid trapped air is the vaccum filler. Again, it attaches to the filler neck of an empty system (or partially filled). You use an air line to create a vaccum in the cooling system, which allows for leak checks. (Just like an A/C evac). Switch over to a coolant fill line and open the valve. The vaccum will pull the coolent in, no air = no air pockets. A bit more pricey for a one time use, but very easy and effective on the worst cases, such as old Toyota MR2's etc. About $125-140.

Another subject has been air flow over the radiator via fans, shrouds, etc. Keep in mind that all that air coming into the engine compartment also has to leave. Especially noticeable on big block cars where there is less room around the edges. ERA recommends cutting away sections of the inner wheel well behind the tire, at header level and below, and the heat shield on the header helps keep dirt out of the rest of the compartment. Back in the day when I actually drove my car on the street regularly, I kept a block of foam rubber behind the seat in case I got caught in traffic. Popped the hood and propped it on the foam to allow more air flow at low speed. A friend of mine used a cut down fan on the water pump, just to force the air out of the engine compartment, past the engine. One of the cars used in the Gumball Rally has vents in the hood for the same purpose.

Don