Aerodynamic Discussion Thread
#443
Senior Member
iTrader: (1)
Join Date: Dec 2008
Location: Manassas, Virginia
Posts: 1,242
Total Cats: 57
I've been wondering why airfoil shapes are still being developed and are team secrets. I would have thought that an optimal shape would have been found long ago and would be public knowledge now. I mean they're all slight variations of a teardrop shape, right? Just find the shape with the best ratio of drag vs. lift.
#444
I've been wondering why airfoil shapes are still being developed and are team secrets. I would have thought that an optimal shape would have been found long ago and would be public knowledge now. I mean they're all slight variations of a teardrop shape, right? Just find the shape with the best ratio of drag vs. lift.
#445
Going back to this picture, is there any other practical place on the car for the exit duct? Wondering what options would be for an RX7 where you don't have a trunk or have extremely limited spacing between the tail lights. Alternately, would you still see a benefit, albeit a diminished one, if you had to neck down the exit to be narrower than the inlet?
#450
I'm in a bit of a vent conundrum.
I was making a fiberglass outlet duct coming off the radiator that would exit the sides of the hood so as not to direct air into a forward facing hood scoop. However, the duct is very large and is creating issues with brake duct locations, accessibility to engine accessories, coolant hose routing, and is occupying space I may need for future "upgrades".
This drives me back to the traditional center-exit ducted radiator vent which is fine. However, I'm also not wanting to force feed warm air into my throttle body. Does anyone foresee this being an issue if I were to use a cowl induction setup with a center exit radiator duct? Options are very limited, though an offset cowl induction setup may be possible now that the brake booster/master cylinders are gone.
I was making a fiberglass outlet duct coming off the radiator that would exit the sides of the hood so as not to direct air into a forward facing hood scoop. However, the duct is very large and is creating issues with brake duct locations, accessibility to engine accessories, coolant hose routing, and is occupying space I may need for future "upgrades".
This drives me back to the traditional center-exit ducted radiator vent which is fine. However, I'm also not wanting to force feed warm air into my throttle body. Does anyone foresee this being an issue if I were to use a cowl induction setup with a center exit radiator duct? Options are very limited, though an offset cowl induction setup may be possible now that the brake booster/master cylinders are gone.
#451
Assuming you are using the old style filter that sits on top of the "carb" (I noticed you're running Holley EFI), I would run a standard hood vent, and then get an air filter cover that you can attach hoses/pipes to, to route air from the front bumper or fenders.
Also, if you were to go that route, you would probably want to close up that forward facing scoop.
Also, if you were to go that route, you would probably want to close up that forward facing scoop.
#453
Supporting Vendor
iTrader: (3)
Join Date: Jul 2006
Location: San Diego
Posts: 3,303
Total Cats: 1,216
I would not want to have my motor intaking the hot radiator exhaust air.
"Ram air" is virtually a myth (until you're talking about a well-engineered setup at 150mph like on the yamaha R1), so given that you can't find a packaging solution other than a center hood vent just forward of the hood scoop for the intake, I would say close off the front of the scoop and open up the back side. Essentially changing it from a 'scoop" to a "cowl" , although this won't solve the issue entirely because the warm air will still be passing over the hood and get inhaled from the back side, it would give the cooler air around the car more time to mix with that warm air before it reaches the intake, so probably net effect would be cooler intake air.
Another option might be a vertical flap ~1-2" forwards of the scoop opening, same height as the scoop - basically a big gurney flap to create some lower pressure right in front of the scoop opening. This could help push hot air up to pass above the scoop, and the scoop would source air from the sides more.
-Ryan
"Ram air" is virtually a myth (until you're talking about a well-engineered setup at 150mph like on the yamaha R1), so given that you can't find a packaging solution other than a center hood vent just forward of the hood scoop for the intake, I would say close off the front of the scoop and open up the back side. Essentially changing it from a 'scoop" to a "cowl" , although this won't solve the issue entirely because the warm air will still be passing over the hood and get inhaled from the back side, it would give the cooler air around the car more time to mix with that warm air before it reaches the intake, so probably net effect would be cooler intake air.
Another option might be a vertical flap ~1-2" forwards of the scoop opening, same height as the scoop - basically a big gurney flap to create some lower pressure right in front of the scoop opening. This could help push hot air up to pass above the scoop, and the scoop would source air from the sides more.
-Ryan
#455
Sorry, probably not giving a good image here.
Radiator will be a sealed duct that exits just forward of the hood centerline, with a small gurney flap on the leading edge. The rest of the hood right now is flat.
My line of thinking is along the lines of ThePass right now - the radiator exit air would likely be drawn through a cowl opening, which is why I was contemplating trying to offset a cowl-induction based intake that was biased off to one side.
Radiator will be a sealed duct that exits just forward of the hood centerline, with a small gurney flap on the leading edge. The rest of the hood right now is flat.
My line of thinking is along the lines of ThePass right now - the radiator exit air would likely be drawn through a cowl opening, which is why I was contemplating trying to offset a cowl-induction based intake that was biased off to one side.
#456
Senior Member
iTrader: (1)
Join Date: Dec 2008
Location: Manassas, Virginia
Posts: 1,242
Total Cats: 57
Why not vent the radiator underneath the car? There should be low pressure there to pull air through the rad. Lower the splitter a little bit to return the air flow volume to what it was before the vent so as not to lose downforce. Or maybe it will need more air (raise splitter) to keep the under-car air moving and therefore pressure low.
#457
Senior Member
Thread Starter
Join Date: Oct 2011
Location: The Race Track & St Pete FL
Posts: 638
Total Cats: 57
I the reason I want to run a hood radiator is 1 the radiator has more air flow to disperse the heat and 2 is because, look at the CFD of a Miata. There is a big negative pressure zone right where the vent would exit.
#458
Supporting Vendor
iTrader: (3)
Join Date: Jul 2006
Location: San Diego
Posts: 3,303
Total Cats: 1,216
Radiator exhaust exiting hood is preferrable over under car, but it's very difficult to accomplish on a miata without relocating the radiator. On an FC with that engine config, might be entirely possible to fit the necessary ducting. If that's the case, definitely better to try to make that happen than go the easy route of letting it exit under the car.
-Ryan
-Ryan
#459
Radiator exhaust exiting hood is preferrable over under car, but it's very difficult to accomplish on a miata without relocating the radiator. On an FC with that engine config, might be entirely possible to fit the necessary ducting. If that's the case, definitely better to try to make that happen than go the easy route of letting it exit under the car.
-Ryan
-Ryan