Question about engine compartment cooling fan
10-19-2014, 07:17 PM
#31
^beyond thermal reasons, it would be better to suck air from the bottom to top for lift/.d.f. reasons....my fan runs full-time, and should be better for it, reasoning being better airflow/cooling for all the coldside and post-intercooler plumbing....I want to wrap my pre-turbo airbox and plumbing
Issue is that speed, I suspect the predominate airflow through the engine bay is upwards. That is it goes from under the car, through the engine bay and up through the rear deck lid vents. Someone correct me if I'm wrong in my assumption.
If that were true, then the fan being run all the time would be fighting rather then assisting cooling. Fans in most cars are only run at idle, low speeds as there is not sufficient airflow in those conditions.
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10-20-2014, 11:47 AM
#33
pretty sure Durametric has capability to datalog engine compartment temps....anyone want to do a comparison fan vs no fan?
10-20-2014, 03:55 PM
#34
Race Director
While I agree that cooler is better (in warm climates), I do question having the fan on all the time.
Issue is that speed, I suspect the predominate airflow through the engine bay is upwards. That is it goes from under the car, through the engine bay and up through the rear deck lid vents. Someone correct me if I'm wrong in my assumption.
If that were true, then the fan being run all the time would be fighting rather then assisting cooling. Fans in most cars are only run at idle, low speeds as there is not sufficient airflow in those conditions.
Issue is that speed, I suspect the predominate airflow through the engine bay is upwards. That is it goes from under the car, through the engine bay and up through the rear deck lid vents. Someone correct me if I'm wrong in my assumption.
If that were true, then the fan being run all the time would be fighting rather then assisting cooling. Fans in most cars are only run at idle, low speeds as there is not sufficient airflow in those conditions.
These cars have superior aerodynamics and part of this involves keeping air out from under the car. One can't have a stable car at high speed with much air under the car.
The air pressure above the rear engine compartment lid is more than the air pressure under the engine compartment. The fan is there to help move air through the engine compartment at lower speeds or when the car is stopped.
Remember, front engine cars have one (or more) radiator fans that not only pull air through the front mounted radiator but blast this air into the engine compartment. This works to keep engine compartment temperature down.
Our Turbos of course have the engine mounted at the rear and there is no radiator fan to help keep the engine compartment temperature under control. This is why there is an engine compartment fan and why it can be set (fused) to run all the time.
If the fan doesn't run all the time I would seriously consider installing the fuse so it does.
Keeping the engine compartment heat down can only help prolong the life of the engine compartment hardware.