[JLMounce]

It is absolutely true that copper is a better heat conductor than aluminum. That's not the whole story though.

On a brass/copper radiator, the copper fins have to be attached to the brass tubes. That's done with either solder or brazing depending on the construction methods. This creates a thermal choke point that diminishes the heat transfer from the fins to the tubes and thus into the coolant. Because the solder or brazing process introduces extra material between the fins, this also means the fin counts are necessarily less. As the radiator sees pressure build, the tube sizes are also limited because due to ballooning of the soft tubes. This means you need to stack additional cores to reach enough surface area. What gains you get from using the superior thermal conductivity of copper is reduced by how the unit is manufactured.

Aluminum radiators are constructed using controlled atmosphere brazing, which eliminates that thermal choke point. Aluminum being stronger also allows for larger tubes and tighter fin counts without external brazing alloy or soft solder that reduces fin count.

Point being, you can find brass and copper radiators the same as you can find aluminum radiators, but in comparable price points, I wouldn't expect the copper/brass unit to cool as well because it's likely constructed with soft solder. Even the more expensive units (some as much as $1500 for just the radiator) are still using silver alloy brazing material, that again creates a thermal choke below the heat transfer rate of an aluminum unit. There's a reason OEM's don't use copper/brass radiators any longer. For the needed cooling capacity, they are more expensive, heavier and take up more space.

As far as the fans are concerned, your radiator doesn't know how is in front or behind it. If you need 3000cfm to cool your engine, doing so with an electric fan or mechanical fan doesn't matter, just as long as you get there.

I can tell you, this is the best my car has ever cooled itself. It's still not perfect and I've always had a slight to moderate idle heating problem. I've had everything now from a factory shroud with copper 3 core radiator and the factory 19" flex fan, an aluminum radiator with a single 15" electric fan and now another aluminum with dual 14" electric fans.

I had the car out in 101 degree heat this weekend and the setup ran at or below 190 while moving, but did see increased time to creep at idle. Still not enough to really be worried about unless I got caught in a sustained traffic jam. This is what's working for me. If you prefer mechanical fans and copper/brass radiators and those are working for you, that's great.

[Shiny]

Curious how much of the heat at idle is coming off your transmission/converter? If you dump any of that under the hood, it may be a contributor?

[JLMounce]

Originally Posted by Shiny

Curious how much of the heat at idle is coming off your transmission/converter? If you dump any of that under the hood, it may be a contributor?

I have a large derale cooler (passive only) that is mounted in front of the radiator. It likely has some type of an effect as it's heating air prior to entry to the radiator core in that area. But it's not dumping that heat into the engine bay itself.

I had this same issue previously with a much smaller trans cooler that was mounted out of the way of the core. That was with a more stock type setup with a TH400 and mild converter.

Since I've been in solve mode for the idle creep specifically, I've been looking at some smaller details such as radiator seals. My car in the entirety of my ownership has never had the radiator seals in the front that seal up from the frame horns to the core support. Nor has it had the inner fender splash shields, or the rear hood seal. My research on this is limited and there's not much out there on testimonials, but if the stock cooling system was designed around having those in place and forcing hot air to travel down, under the trans tunnel and beneath the car, I may be inhibiting that flow.

The altitude I run the car at (between 4500-5000ft) has a minor effect as there's less atmosphere to actually carry heat away, but really I'm chipping away at the edges now.

[Shiny]

Thanks...just a thought.

The shrouds you are missing sound like good intuition!

Do you have a way to monitor the temperature of your trans fluid?

I had to add a cooler to our truck when I found out how hot the tranny got when pushing a small camper around the yard. I had no appreciation for the heat generated before this educational experience.

I also learned there was a thermostat in the trans that let the heat climb too much before allowing the fluid to circulate to the cooler. Dealer had a service bulletin and replaced with a lower-temp stat. Not the same as yours but there's a LOT of heat that has to go somewhere..

[JLMounce]

Originally Posted by Shiny

Thanks...just a thought.

The shrouds you are missing sound like good intuition!

Do you have a way to monitor the temperature of your trans fluid?

I had to add a cooler to our truck when I found out how hot the tranny got when pushing a small camper around the yard. I had no appreciation for the heat generated before this educational experience.

I also learned there was a thermostat in the trans that let the heat climb too much before allowing the fluid to circulate to the cooler. Dealer had a service bulletin and replaced with a lower-temp stat. Not the same as yours but there's a LOT of heat that has to go somewhere..

It's a bit of a pain because of where I have my trans computer located, but yes I can monitor temperature. I don't know what it runs in 100 degree heat, but average temps I usually see if I'm datalogging the trans, or outright viewing the controller ranges from 155-170 depending on what I'm doing.

The fact that this is a lockup converter, helps with heat quite a bit. It's definitely hottest in slow moving traffic where I'm on and off the throttle without the converter being locked up.

[65madgoat]

[QUOTE=JLMounce;6623880]It's a bit of a pain because of where I have my trans computer located, but yes I can monitor temperature.


I say time for a 5 speed and watch your temps drop 5-10 degrees ;-)

[JLMounce]

Hah, don't tempt me!