Project S2000: Part 23 – Testing Air Temps Through Coolers and Vents


Cruising on the freeway at around 70mph, I waited from the coolant and oil temperatures to stabilize (thanks ARK Design MFD-II) before turning on the Omega thermocouple data logger. You may recall I have the Mocal 170F thermostat which is why my oil temperature is only 76 deg C here. Maybe someday, I’ll upgrade to the Mocal 200F thermostat.
The ambient air temperatures were in the mid-70s. The air temperature coming off the radiator was roughly 120 deg F with the surface temperature of the radiator (purple line) measuring roughly the same. The air coming off the oil cooler was much warmer being in the mid-150s.

So as I had predicted, the air temperature coming off the radiator was still relatively cool (i.e. much cooler than the oil temperature) and is suitable for cooling the oil in the oil cooler mounted behind the radiator. An important thing to note is the air coming off the radiator 40F-50F hotter than the ambient air temperature. I mention this because you see tons of turbo kits sucking up hot air coming off the radiator. As we all know (if you’ve been reading out Turbo Tech articles), turbos love cold air. Heck, even naturally aspirated cars love cold air as I showed in testing my hood NACA duct. So, make sure you suck in cold air as no one likes something full of hot air.

Along with my unconventional oil cooler installation, I went against the grain when it came to venting the stock S2000 hood. You see, lots of people cut holes in their S2000 hoods in the attempt to make their cars run cooler. Cutting holes did have the effect of keeping temperatures under the hood cooler. However, that is different than keeping the coolant and oil temperatures cooler. When a couple guys actually track tested the hoods with holes, they found their fluid temperatures actually increased. Why? Because air was making its way into the engine bay by way of the holes behind the radiator therefore creating a high pressure zone behind the radiator. The higher pressure behind the radiator restricted the airflow through the radiator causing coolant temperatures to go up. Remember, flow is driven by pressure differential. So, I vented my hood in a manner that basically created louvers. I tested the vented hood on track and it did indeed improve coolant and oil temperatures, but what exactly were the air temperatures exiting the vents?

I previously did some yarn/tufts testing and it did indeed appear hot air was making its way out of my vents.
I left the #1 thermocouple in the front bumper and relocated the other three to the openings in my track hood.
On the side vents, I place the thermocouples in the second opening. This is the passenger side.
This is the thermocouple on the driver’s side (sorry for being out of focus).

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