Pro/Forums - View Single Post - Why is pull-pull better than push-pull?

HAL-9000 · 06-02-2004, 03:16 PM

Its pretty basic why pull pull works better though I hadn't thought about it 'till I started reading this thread.

Basically, so much air has so much cooling capacity. More air the better, and we fool ourselves into thinking more CFM=more air. But really a 50CFM fan at sea level will beat a 60CFM fan in Mexico City, because there's just less air per cubic foot up there around 7000 feet.

The pull-pull config probably moves a smaller volume of air (no data on that, just a thought experiment) than the push-pull, but at a higher presser per CF. Basically as far as cooling goes, the more air molecules blowing over my rad the better. If I have a higher pressure, that means I have more of those molecules in a given volume, so my radiative system can do more work. Each turn of the second stage fan gets to scoop more molecules of air than if it was just sitting there open-faced.

Its kinda like a supercharger intercooler, makes the air denser before it goes into it, hence there is more oxygen to burn in the fixed volume of the engine.

06-02-2004, 03:16 PM	#25
HAL-9000 Cooling Savant Join Date: May 2004 Location: San Diego, CA Posts: 202	Pull-Pull works better because of pressure Its pretty basic why pull pull works better though I hadn't thought about it 'till I started reading this thread. Basically, so much air has so much cooling capacity. More air the better, and we fool ourselves into thinking more CFM=more air. But really a 50CFM fan at sea level will beat a 60CFM fan in Mexico City, because there's just less air per cubic foot up there around 7000 feet. The pull-pull config probably moves a smaller volume of air (no data on that, just a thought experiment) than the push-pull, but at a higher presser per CF. Basically as far as cooling goes, the more air molecules blowing over my rad the better. If I have a higher pressure, that means I have more of those molecules in a given volume, so my radiative system can do more work. Each turn of the second stage fan gets to scoop more molecules of air than if it was just sitting there open-faced. Its kinda like a supercharger intercooler, makes the air denser before it goes into it, hence there is more oxygen to burn in the fixed volume of the engine.