BTU Controversy

There is a huge controversy among different makes of performance radiators about BTU's. While the actual BTU's may be important, what is more important is how the radiators perform. Many manufacturers are making big claims as to the amount of BTU's their radiators can shed, yet they still don't perform as well as radiators from AWR built using Ron Davis Racing cores. Here is some information to consider.

The BTU differential test must be performed in a totally controlled environment. The ambient air and air density must be constantly monitored. The British thermal Unit of measure [Btu] is a standard of the industry and measures the amount of energy needed to increase or in our situation, decrease the temperature of 1 pound of water by 1 degree of Fahrenheit.

All of the above points will have an effect on the total Btu’s removed from the radiator and in saying so the only way to correctly measure the Btu differential between manufacturers is to perform all test’s in a totally controlled environment. The test must be run on non-bias grounds and monitored and data logged consistently. The test must be run with one product and then all temperatures must be returned to the starting point and the next test must be run in the exact same fashion.

All of our tests have been done on a racetrack and A.W.R. has never tested the competition. There is no need to! Our radiators have proven to succeed in the environment that they perform in and have not needed to be changed to another brand to provide additional cooling.

A controlled environment test would provide total BTU differentials between brands but may not provide the same basis at a racetrack environment due to the many uncontrollable variables.

Other competitors claim to have direct fit applications, that’s because they have copied and learned from us.

Variables determining Btu differential

• Temperature entering radiator core
• Temperature exiting radiator core
• Fin proximity to header tank
• Radiator total entrance sealing
• Core [tube] thickness
• Fin count
• Fin design
• Incoming air speed
• Exiting air speed
• Exiting air ducting
• Exiting air interference, i.e. fans, water pump, sway bar etc.
• Incoming air ducting
• Ambient air temp
• Air density
• Air temperature probe location
• Air pockets in system
• Water pump speed
• Engine oil temperature
• Exhaust gas temperature

A Letter from Doug Shulz, General Manager of Ron Davis Racing Products:

Each radiator can be made to capture a select mode of operation, from street use with A/C, to full race applications. Saying that the Btu rating of a radiator is better than another doesn’t reflect the entire range of uses for that radiator. One design will give up more Btu’s with lower airflow, but may have less overall heat removal capacity given the large airflow at speed, due to the low fin count or lesser design. Another may have a higher maximum rating but may not flow as well at lower speeds. Comparing Btu ratings does not capture the intended use at all the possible ranges of applications, nor does it capture the varying needs for configuration changes on vehicles like air dams, hood vents, water pumps, etc. Radiator test rig comparisons would have to vary airflow, water flow, RPMS, horsepower, ambient temperature and humidity and vehicle configuration over the entire range and combination of possible values in order to say which radiator is “better”. Also, having a higher Btu rating in excess of the needs of the vehicle serves no purpose. Empirical testing of Ron Davis Racing Products radiators has consistently proven them on the track and street for years as durable, efficient and beautiful units for thousands of customers over the broadest range of applications imaginable.

Doug Schulz
General Manager
Ron Davis Racing Products