Here is how this usually goes.
Question 1: “How many cores are in your 1930 Model A radiator?”
Answer: “One. There is one core in our radiator.”
Reply: “That is not what I meant.”
Question 2: “Okay smart aleck. What I mean is how many rows are in the radiator?”
Answer: “There are two rows arranged in a staggered configuration. “
Reply to the answer: “Hmmm? My book says Henry Ford had four rows.”
Question 3: “Okay so how many tubes then?”
Answer: “There fifty seven tubes in the core.” (see below)
Reply to the answer: “Ohhh? My book says there are 102 tubes in a 30-31 Model A radiator.” This can't be heavy duty.
Oh contraire. Its the heaviest dutiest!
We know what Henry made but we decided to make it better. Ford used 94 – 1/4” round tubes in 1929 and 102 3/8” oval shaped tubes in 1930. In a 1930-31 Ford Car or car based pick-up made today there are 57 - 3/4” flat tubes (highly elliptical shaped tubes). Yes the 57 tubes are 44% fewer than Ford's OE design but due to their shape, those tubes have 9% more cubic volume and 33% more interior wall area contacting the coolant. So you can get more cooling with fewer tubes or perhaps we should say, you get more cooling with more contact.
In addition to the tube shape improvements, the vast majority of the radiators we sell for Model As have the 10 fins per vertical inch and thus have 40% more fin surface area. Each fin has 12 fin louvers between each tube to disrupt the airflow.
It would be better still to consider a few more factors of heat exchange design.
- the materials used the construction
- the amount of contact area of coolant-to-tube wall for electron exchange
- the amount contact between fin and tube wall
- the fin density
- the core face area exposed to air
- the aggregate surface area of the core
- the surface disruption of air through the tube array
- the surface disruptions of the air on the fin surface
- the tube wall thickness
- the fin thickness
Ford engineers knew these factors and designed for efficacy (and we suspect cost). We see evidence in the evolution of radiators e.g. tube shape, tube wall thickness, fin density, fin surface, fin thickness, core dimensions that demonstrate that they were improving constantly to meet the demands of more powerful (hotter) engines. We take the same approach but we have the luxury of technological advances in material formation and construction.
Here's a chart with tubes scaled to illustrate the importance of tube surface area