Quote:
Originally Posted by HO455
Currently other than the grille you have no restriction in front of the radiator. Adding a pusher fan will restrict air flow through the radiator in the area where the fan mounts and in the center of the fan where the motor is. In addition at speed it is possible for the pusher fan to create a high pressure bubble that prevents air from entering the fan blades and the radiator behind them. Even though the fan blades are moving they are still flat objects that 20-30% of the incoming air will hit and bounce off of. The faster the incoming air is the harder it bounces off of the blades.
The devil is in the details when adding a pusher fan. Matching the performance of the 2 fans so they complement each other is where the real work is.
Some late model high performance Corvettes have both a puller fan and a pusher fan that the base model Vettes don't get. GM discovered a need for more cooling and then carefully engineered a solution. I have no knowledge as to how or when the fans operate or are controlled. Or even what the goal was. I've just seen them and was surprised to see the pusher fan.
I just noticed you have A/C. How is the air flow through the condenser?
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HO455...The A/C condenser does take up the entire opening leading to the radiator and there is also an external trans-cooler in front of the condenser on one side, so I imagine combined they slow things down a bit...which is why I thought an electric pusher fan installed behind the condenser and up tight to the radiator would actually speed things up some. The condenser allows decent flow through the fins as I can see through them better than I can though my new radiator! Having the condenser in front of the electric fan should diminish the "bouncing off" effect, don't you think? I totally get what you mean with the "balancing act" between the two fans...actually seems like "trial and error" is the only way to figure it out (unless one has a wind-tunnel or other sophisticated facility of some sort). I read the link you sent...really good info there...and it seems like my set-up with regards to fan placement within the shroud and fan clutch proximity to the radiator fall into what they say it should be (1/2" of my fan blade edge extends beyond the shroud...and my fan clutch is 3 1/2" from the back side of the radiator). While those are the minimums they suggest, moving the fan blades further out of the shroud by using the short shaft Hayden fan clutch will also move the fan clutch further from the back of the radiator by one inch (just over of the 4" max they talk about...and some say 4" is too much anyway!). The other thing is that the Hayden short shaft clutch is only available as Heavy Duty, and the Severe Duty has a more aggressive lock-up feature, which is recommended. For $60, it might be worth buying it to know for sure? Ha...something else to think about! Thanks for the follow-up info...I feel as though I'm absorbing some education that actually appeals to me!
***UPDATE*** I was reviewing the notes I made before I started removing the original parts and realized that the measurement between the radiator and the face of the thermal clutch is actually 1 3/8" not 3 1/2" (not sure where I got that number from???) so using the short shaft clutch would only put the total distance away at 2 3/8" (more than the optimal distance, but should still register the heat enough to work correctly). That would move the back edge of the fan blades out of the shroud to a total of approximately 1 1/2", which could make a difference. If it doesn't help, I can always change it back as I'm kind of getting good at unbolting these same parts!
Woody