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


Lastly, here is the thermocouple in the center vent.
This chart shows highway cruising with the temperature spikes being stopped at the lights for off-ramps. Ambient temperatures were again in the mid-70s. During steady state cruising, the hottest air came out of the driver’s side vent at around 120F with the center vent close behind at about 110F. The interesting thing is the passenger side vent (oil cooler side) with an air temp of only about 90F. With the car at a stop, all the temperatures spike to roughly the same hotter temperatures.

If the oil cooler is on the passenger side of the car and we measured the hottest air temperatures coming off the oil cooler, why is the passenger side venting the coldest? We suspect it has to do with flow paths and restrictions in the engine bay.


This is a view of the passenger side of the engine bay. Notice the stock air box takes up a large chunk of volume behind the radiator and oil cooler creating resistance to airflow to the passenger side hood vent.
You can see how the air box goes down to the frame effectively blocking any airflow there. So the only real path for airflow is under the frame rail in that gap with the steering rack and oil line going through. You can just see the bottom of the fan mounted on the back of the oil cooler.
The center vent is located above the air box, so air coming off the top of the radiator has a clear flow path over the air box and out the vent. With all the hot air coming off the radiator, you can understand why it’s a good idea for the air box to be plastic which has a relatively low level of thermal conductivity. A metal tube for an intake in this location behind the radiator would pick up the heat and transfer that into the air going into the engine; not good. Another thing to notice is that the back of the oil cooler pretty much extends to where the air box begins.

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