Testing the Airflow Kit

We do a lot of development at Flyin' Miata, and the airflow kit is a good example of testing producing a better product. We tortured a series of cooling setups on our specially-built dyno rig. Here's how it was done.

The testing consisted of setting up an engine on our dyno and running it at a fixed load. This allowed us to generate a consistent level of heat for a long period of time. The engine was run until the inlet and outlet temperatures were stable for a 5 minute period. The engine was fitted with a thermostat that opened at approximately 71º, and the load was enough that the thermostat was not a factor - it was simply down to the ability of the radiator to shed heat. We instrumented the temperature of the inlet, the temperature of the outlet, the ambient temperature and the time. The first run for each setup was thrown out to ensure the entire system was heat-soaked, although that didn’t make a significant difference.

Here are the numbers for a set of stock fans, a set of large fans run without a shroud, and our new Stage 1 airflow kit. All temperatures are in degrees Celsius. 1 degree Celsius is 1.8 degrees Fahrenheit, for those who aren't used to the metric system.

As you can see, our new setup runs considerably cooler than the stock or unshrouded fans and takes much longer to get to full temperature. It’s important to note that the depth of the shroud is critical - a shroud close to the radiator will block airflow over most of the core.

We then installed an AC condenser and intercooler in front of the radiator, boxed in. It’s harder for fans to pull air through a stack of heat exchangers.

The time-to-temperature numbers are interesting in this one, but it may be due to the lower final temperature of the Stage 1 setup. The higher airflow keeps the radiator (and the engine) from getting as hot in the first place. Remember, the engine had stabilized at these temperatures for five minutes before we stopped testing, so a car fitted with a Stage 1 setup would run 7 degrees (12.6º Fahrenheit) cooler than one with stock fans according to our tests. That's a pretty significant difference! Of course, the Stage 2 will pull even better, especially with the heat exchangers as it is a higher torque fan that deals well with extra restriction. The fans used for the Stage 2 were not available at the time these numbers were generated.

We’re still testing, and you will see some new radiator designs coming from Flyin’ Miata as a result of this work.

Flyin' Miata Stage 1 airflow kit
Flyin' Miata Stage 2 airflow kit