Aerodynamics
10-12-10, 02:40 PM
#1
Aerodynamics
Figured I'd share some experiments w/ hood vents and aerodynamics from a few years ago. 
I bought a few spare hoods and made different designed vents. I did come across a design that actually helped front end stability, but it was through a fair amount of trial and error. I'll briefly mention my designs and results.
Design 1: Evo style open vented hood w/ no ducting.
Results: Front end lift at freeway speeds, and much lower under-hood temps while at low speeds.
Design 2: Traditional drop vent hood w/ no upper air guide.
Results: More front end lift at freeway speeds due to a larger low pressure pocket of air. Engine bay temps slightly greater than above design with greater stability in coolant temps.
Design 3: Traditional drop vent hood w/ a full duct and smaller exit than entrance.
Results: Front end was more stable than above designs and felt superior to an un-vented hood. Much more stable coolant temps under load.
First 2 pictures are of Design 1, and show the space available. I have no pictures of other 2 hoods on my laptop.
I hope this helps out anyone who is looking to work on the aerodynamics of their FC or what have you.
I bought a few spare hoods and made different designed vents. I did come across a design that actually helped front end stability, but it was through a fair amount of trial and error. I'll briefly mention my designs and results.
Design 1: Evo style open vented hood w/ no ducting.
Results: Front end lift at freeway speeds, and much lower under-hood temps while at low speeds.
Design 2: Traditional drop vent hood w/ no upper air guide.
Results: More front end lift at freeway speeds due to a larger low pressure pocket of air. Engine bay temps slightly greater than above design with greater stability in coolant temps.
Design 3: Traditional drop vent hood w/ a full duct and smaller exit than entrance.
Results: Front end was more stable than above designs and felt superior to an un-vented hood. Much more stable coolant temps under load.
First 2 pictures are of Design 1, and show the space available. I have no pictures of other 2 hoods on my laptop.
I hope this helps out anyone who is looking to work on the aerodynamics of their FC or what have you.
10-12-10, 04:24 PM
#3
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Thanks for the information. I bought an Evo hood with the intent of removing its vent (with a little surrounding sheetmetal) and inserting the resulting piece into an aluminum convertible hood. I haven't got around to doing the labor, yet, but I'll refer back to your results. Could you post a picture of your ducting?
TIA,
TIA,
10-12-10, 07:02 PM
#4
I need to dig up my old PC from storage and buy a screen as well. I will see what I can do though. All of my pictures should be on there.
Rivets and epoxy were used as well as spare sheet metal from the first hood to make the duct. The duct was attached to the bottom of the hood and sat just below the motor of the e-fan. Figured it would be good to have some airflow around the engine to keep things cool.
Rivets and epoxy were used as well as spare sheet metal from the first hood to make the duct. The duct was attached to the bottom of the hood and sat just below the motor of the e-fan. Figured it would be good to have some airflow around the engine to keep things cool.
10-13-10, 09:14 AM
#6
It was observed in how the car drove at speeds above 60mph. Normally due to the cars alignment and overall configuration it would track dead straight at any speed, and the front end felt very stable in higher speed corners.
When using the first 2 designs the car would want to wander a huge amount on the freeway, and during high speed corners the car felt notably more unstable. No changes were made to anything else to keep as many variables constant, thus it was determined that it was lift.
I also did many tests w/ tufts of yarn and in the first 2 designs, the yarn was never stable -even towards the back of the hood. It wasn't until I made the duct's exit smaller and had a greater controlled airflow that the yarn stayed very stable before and behind the duct.
By the way, the light kit you made- loved em!
When using the first 2 designs the car would want to wander a huge amount on the freeway, and during high speed corners the car felt notably more unstable. No changes were made to anything else to keep as many variables constant, thus it was determined that it was lift.
I also did many tests w/ tufts of yarn and in the first 2 designs, the yarn was never stable -even towards the back of the hood. It wasn't until I made the duct's exit smaller and had a greater controlled airflow that the yarn stayed very stable before and behind the duct.
By the way, the light kit you made- loved em!
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10-13-10, 12:45 PM
#10
It was observed in how the car drove at speeds above 60mph. Normally due to the cars alignment and overall configuration it would track dead straight at any speed, and the front end felt very stable in higher speed corners.
When using the first 2 designs the car would want to wander a huge amount on the freeway, and during high speed corners the car felt notably more unstable. No changes were made to anything else to keep as many variables constant, thus it was determined that it was lift.
I also did many tests w/ tufts of yarn and in the first 2 designs, the yarn was never stable -even towards the back of the hood. It wasn't until I made the duct's exit smaller and had a greater controlled airflow that the yarn stayed very stable before and behind the duct.
By the way, the light kit you made- loved em!
When using the first 2 designs the car would want to wander a huge amount on the freeway, and during high speed corners the car felt notably more unstable. No changes were made to anything else to keep as many variables constant, thus it was determined that it was lift.
I also did many tests w/ tufts of yarn and in the first 2 designs, the yarn was never stable -even towards the back of the hood. It wasn't until I made the duct's exit smaller and had a greater controlled airflow that the yarn stayed very stable before and behind the duct.
By the way, the light kit you made- loved em!
http://backseatcuddler.com/wp-conten..._circuit_3.jpg
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