Thermal Conductivity

Terms are constantly thrown around in the car industry. Most of us believe we know the meaning but in reality we just understand the concept, not the process and or cause.

A debate sparked in the office over Cast-Iron vs Aluminum that lead me to attempt a blog post concerning a subject in Chemical Physics.

I’m clearly a glutton for punishment.

Still have your attention? I’m impressed!

So we battle with Thermal Conductivity pretty often when modifying a car. Let it be a larger intercooler, radiator, Ceramic coating, heat barriers and brake ducts the main goal is to either block heat to begin with or cool something down.

Photo by Brandon Adams

Heat is always a problem and understanding what’s going on a at this level may help you make more power, a decision on a platform or even figure out a resolution to a nagging issue.

Let’s focus on the differences between Iron and Aluminum to keep the argument and article as simplistic as possible.


Ok, so here are some fun facts




Aluminum is about half the weight of Cast-Iron

Costs four times more than Iron

Aluminum has 1/3rd of the thermal conductivity when compared to Iron.  (cal/sec)/(cm2 C/cm)

Aluminum loses one-third of its strength at 200 degrees.

Facts about our friend Fe:

Costs about .25 cents a pound

Extremely high tensile strength

Takes longer to heat as well as cool “Why Cast-Iron cooking pans rule”


So with that being said we know the following:

Aluminum is pretty pricey lighter, soaks and releases heat about three times faster than iron but loses one-third of its strength on a normal day in the south at a mere 200 degrees.

Iron is cheap, heavy and overall more stable


I know what you’re thinking.

Iron blocks are awesome!


Stay tuned to the next post for a deeper look into the benefits of both Iron and Aluminum engine blocks.