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Old 11-01-2021, 05:04 PM   #1
jimoblivion
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Default Subaru Hood Scoop in Aerodynamic Testing

Ok, so I saw a video where they were talking about the Subaru hood scoop in aerodynamic testing, they said the scoop is equal to having a brick sitting on the hood of your car. If that's the case, why does the new WRX have a hood scoop? The Ascent and Legacy XT's don't have a hood scoop and they're turbocharged, not sure about Outback XT's hood.
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Old 11-01-2021, 05:16 PM   #2
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Originally Posted by jimoblivion View Post
Ok, so I saw a video where they were talking about the Subaru hood scoop in aerodynamic testing, they said the scoop is equal to having a brick sitting on the hood of your car. If that's the case, why does the new WRX have a hood scoop? The Ascent and Legacy XT's don't have a hood scoop and they're turbocharged, not sure about Outback XT's hood.
because racecar.
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Old 11-01-2021, 05:21 PM   #3
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I think hood scoops look great, especially the 2004-2005 STI. Has anyone figured out if the new grille-based ducting is as efficient as the hood scoop (for TMIC)?
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Old 11-01-2021, 05:24 PM   #4
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because racecar.
/endthread
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Old 11-01-2021, 07:26 PM   #5
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Originally Posted by Snow Drift View Post
I think hood scoops look great, especially the 2004-2005 STI. Has anyone figured out if the new grille-based ducting is as efficient as the hood scoop (for TMIC)?
I agree, but everyone's looking for that extra 5hp, the hood scoops as they say in aerodynamic testing could save hp?
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Old 11-01-2021, 07:27 PM   #6
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/endthread
No doubt!
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Old 11-02-2021, 09:54 AM   #7
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Originally Posted by jimoblivion View Post
Ok, so I saw a video where they were talking about the Subaru hood scoop in aerodynamic testing, they said the scoop is equal to having a brick sitting on the hood of your car. If that's the case, why does the new WRX have a hood scoop? The Ascent and Legacy XT's don't have a hood scoop and they're turbocharged, not sure about Outback XT's hood.
How is it useless , not trying to argue but pushing fresh air through an intercooler shouldn't be a useless design .......why would a fmic located where it can grab the most air ?
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Old 11-02-2021, 09:58 AM   #8
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Originally Posted by SUPRA180 View Post
How is it useless , not trying to argue but pushing fresh air through an intercooler shouldn't be a useless design .......why would a fmic located where it can grab the most air ?
What? Please rephrase your comment.
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Old 11-02-2021, 10:06 AM   #9
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Originally Posted by SUPRA180 View Post
How is it useless , not trying to argue but pushing fresh air through an intercooler shouldn't be a useless design .......why would a fmic located where it can grab the most air ?
What I was trying to say is if the hood scoop is no good for aerodynamics, why was the hood scoop put on the new WRX? They didn't put the hood scoop on the Legacy XT or the Ascent, which both have the same turbocharged engine. What were they thinking? One person posted earlier, Because Racecar and I get that but most WRX owners for the most part won't be pushing for 400hp. The hood scoop is astatically beautiful, don't get me wrong, just wondered why Subaru decided to keep the scoop for the WRX and not on the Legacy XT which is still the Legacy GT.
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Old 11-02-2021, 11:46 AM   #10
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Originally Posted by jimoblivion View Post
I agree, but everyone's looking for that extra 5hp, the hood scoops as they say in aerodynamic testing could save hp?
Dude, you are totally off base here. The hood scoop is how they are feeding the intercooler, which may as well be a parachute. . . .but it's a parachute that you HAVE to have.
It isn't adding drag because it's a top mount, it's adding drag because it's a heat exchanger and it has to be somewhere.

Do you know what the aerodynamics of a front mount are?
I'll tell you, it's like a parachute.

Mount the thing standing upright on the trunk. Guess what, it will function and it will drag, there's no other way for a heat exchanger to work on a car.

It doesn't matter where you put it, if you put a cooling device anywhere at all it will add drag, it's that simple.
Cars with front mounts simply have more intake area in front, which is drag. You have to plow air through it no matter where it is and you can't just "stack" up heat exchanger after heat exchanger in front, you need dedicated area to make them all work right.

They stuck with the top mount because it is the classic style of that vehicle and at the end of the day it doesn't really change anything aero wise.
You either drag from the hood or you plow more in front.
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Old 11-02-2021, 12:01 PM   #11
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Originally Posted by jimoblivion View Post
What I was trying to say is if the hood scoop is no good for aerodynamics, why was the hood scoop put on the new WRX? They didn't put the hood scoop on the Legacy XT or the Ascent, which both have the same turbocharged engine. What were they thinking? One person posted earlier, Because Racecar and I get that but most WRX owners for the most part won't be pushing for 400hp. The hood scoop is astatically beautiful, don't get me wrong, just wondered why Subaru decided to keep the scoop for the WRX and not on the Legacy XT which is still the Legacy GT.
This has a simple answer: Consumer tastes.

Legacy, Forester, Ascent and Outback compete in a segment which prefers (for the most part) to blend in. A hood scoop screams LOOK AT ME. So, since the competitors all have flat hoods, including TMIC competitors (think old RDX), Subaru did the same.

The WRX retains the hood scoop because it's the easiest way to identify a WRX and the customers like it. You will notice that over the years they have integrated the scoop more and more ever since the 9-2x and 2008. For many years there has been just a bump in the hood and an insert, not a scoop on top of a hole.

The 2022 is the first in a long time to have a more pronounced scoop.

Last edited by Snow Drift; 11-02-2021 at 12:07 PM.
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Old 11-02-2021, 12:19 PM   #12
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Originally Posted by rtv900 View Post
They stuck with the top mount because it is the classic style of that vehicle and at the end of the day it doesn't really change anything aero wise.
You either drag from the hood or you plow more in front.
Ok, I get it
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Old 11-02-2021, 12:20 PM   #13
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Quote:
Originally Posted by Snow Drift View Post
This has a simple answer: Consumer tastes.

Legacy, Forester, Ascent and Outback compete in a segment which prefers (for the most part) to blend in. A hood scoop screams LOOK AT ME. So, since the competitors all have flat hoods, including TMIC competitors (think old RDX), Subaru did the same.

The WRX retains the hood scoop because it's the easiest way to identify a WRX and the customers like it. You will notice that over the years they have integrated the scoop more and more ever since the 9-2x and 2008. For many years there has been just a bump in the hood and an insert, not a scoop on top of a hole.

The 2022 is the first in a long time to have a more pronounced scoop.

Good, very good
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Old 11-03-2021, 01:58 PM   #14
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I think Subaru deserves a little more credit. The top mount is a good design for a rally car. It means the car can sustain a little more front end damage without a boost leak and the shorter piping gives less lag. Rally cars also don't reach the same top speeds as dedicated track cars so the added drag seems like a worth while trade off. I would think that the front mount setup has less drag overall. I can tell you from experience, the TMIC cools better than the FMIC but the radiator loses some cooling ability with an intercooler in front of it. The point is that front area was always going to drag as long as the radiator and condenser get enough air, it's fine.
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Old 11-03-2021, 02:02 PM   #15
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Originally Posted by Vices View Post
I think Subaru deserves a little more credit. The top mount is a good design for a rally car. It means the car can sustain a little more front end damage without a boost leak and the shorter piping gives less lag. Rally cars also don't reach the same top speeds as dedicated track cars so the added drag seems like a worth while trade off..
Ok, makes sense.
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Old 11-03-2021, 03:17 PM   #16
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Originally Posted by Vices View Post
I think Subaru deserves a little more credit. The top mount is a good design for a rally car. It means the car can sustain a little more front end damage without a boost leak and the shorter piping gives less lag. Rally cars also don't reach the same top speeds as dedicated track cars so the added drag seems like a worth while trade off. I would think that the front mount setup has less drag overall. I can tell you from experience, the TMIC cools better than the FMIC but the radiator loses some cooling ability with an intercooler in front of it. The point is that front area was always going to drag as long as the radiator and condenser get enough air, it's fine.
That's part of some of the rationale, but requires some more explanation. When the original Impreza WRX was first introduced into the World Rally Championship, it was during Group A regulations. So the rally car had to closely match the factory produced models (WRX and later the early STI versions). And because the cars were designed with top mount intercooler for packaging (keeps weight closer to axle and less piping than FMIC), the rally car had to use that same setup. But later in 1997 when the regulations allowed the teams to more freely build their rally cars with differences to factory models, the Impreza WRC rally cars used a front mount intercooler. Although as stated above, the FMIC blocks a lot of the radiator, so in the Impreza WRC cars they mounted the FMIC above the radiator, so the two heat exchangers were nearly one on top of the other, I think there was a little overlap. The FMIC took in air from an enlarged grill space. When the engineers had the freedom to do so, and after some years of running a top mount intercooler in the Legacy and Impreza group A rally cars, their data told them that a FMIC was the way to go for top level competition in rallying.
Even with the TMIC removed in favor of a FMIC, the Impreza WRC rally cars from 1997 to 2008/9 still had hood scoops. This was solely for commercial reasons. Subaru wanted the rally car to share a close appearance to the WRX and STi models on the dealer lots. And the hood scoop, as someone said earlier, is an iconic and recognizable feature of Subarus. These hood scoops in the rally cars literally went to nothing. I'm sure the engineers in the Subaru Prodrive team were pissed that they had a non-functional aero feature that added some drag with no benefit. Though they did install a block-off plate in the scoop so it was not sucking in air and creating low-pressure zones were hot ambient engine air could sit.
The most current versions of the Subaru rally cars used in America and built by Vermont SportsCar all use FMICs, not sure if they are V-mounted or not.
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Old 11-03-2021, 03:48 PM   #17
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I think other people answered the original question of why doesn't the new Outback and Legacy have hood scoops best when they said Subaru probably wanted those cars to have a clean look, existing in the market segment that they do.

In case the question was more asking in a technical sense why they don't have hood scoops, I searched for photos of the 2021-2022 cars. Kind of hard to find photos of the engine bay and especially bottom side of the hood for the turbocharged models. What I can tell from the photos is that the ambient air for the top mount intercooler is taken from the grill area above or below the Subaru badge, and there is some ducting on the bottom/interior facing side of the hood that directs it onto the intercooler. I can't see the whole underside of the hood yet, just the aft 1/2 that ducts it straight onto the TMIC.
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Old 11-04-2021, 09:40 AM   #18
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Originally Posted by TitoBandito View Post
That's part of some of the rationale, but requires some more explanation. When the original Impreza WRX was first introduced into the World Rally Championship, it was during Group A regulations. So the rally car had to closely match the factory produced models (WRX and later the early STI versions). And because the cars were designed with top mount intercooler for packaging (keeps weight closer to axle and less piping than FMIC), the rally car had to use that same setup. But later in 1997 when the regulations allowed the teams to more freely build their rally cars with differences to factory models, the Impreza WRC rally cars used a front mount intercooler. Although as stated above, the FMIC blocks a lot of the radiator, so in the Impreza WRC cars they mounted the FMIC above the radiator, so the two heat exchangers were nearly one on top of the other, I think there was a little overlap. The FMIC took in air from an enlarged grill space. When the engineers had the freedom to do so, and after some years of running a top mount intercooler in the Legacy and Impreza group A rally cars, their data told them that a FMIC was the way to go for top level competition in rallying.
Even with the TMIC removed in favor of a FMIC, the Impreza WRC rally cars from 1997 to 2008/9 still had hood scoops. This was solely for commercial reasons. Subaru wanted the rally car to share a close appearance to the WRX and STi models on the dealer lots. And the hood scoop, as someone said earlier, is an iconic and recognizable feature of Subarus. These hood scoops in the rally cars literally went to nothing. I'm sure the engineers in the Subaru Prodrive team were pissed that they had a non-functional aero feature that added some drag with no benefit. Though they did install a block-off plate in the scoop so it was not sucking in air and creating low-pressure zones were hot ambient engine air could sit.
The most current versions of the Subaru rally cars used in America and built by Vermont SportsCar all use FMICs, not sure if they are V-mounted or not.
Yeah as soon as the rules changed it was apples to oranges but the design had a time and a place. I too have moved on to an FMIC, my comments regarding front grill area refer to a more or less factory front end for a car with AC.
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Old 11-04-2021, 11:14 AM   #19
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Originally Posted by TitoBandito View Post
That's part of some of the rationale, but requires some more explanation. When the original Impreza WRX was first introduced into the World Rally Championship, it was during Group A regulations. So the rally car had to closely match the factory produced models (WRX and later the early STI versions). And because the cars were designed with top mount intercooler for packaging (keeps weight closer to axle and less piping than FMIC), the rally car had to use that same setup. But later in 1997 when the regulations allowed the teams to more freely build their rally cars with differences to factory models, the Impreza WRC rally cars used a front mount intercooler. Although as stated above, the FMIC blocks a lot of the radiator, so in the Impreza WRC cars they mounted the FMIC above the radiator, so the two heat exchangers were nearly one on top of the other, I think there was a little overlap. The FMIC took in air from an enlarged grill space. When the engineers had the freedom to do so, and after some years of running a top mount intercooler in the Legacy and Impreza group A rally cars, their data told them that a FMIC was the way to go for top level competition in rallying.
Even with the TMIC removed in favor of a FMIC, the Impreza WRC rally cars from 1997 to 2008/9 still had hood scoops. This was solely for commercial reasons. Subaru wanted the rally car to share a close appearance to the WRX and STi models on the dealer lots. And the hood scoop, as someone said earlier, is an iconic and recognizable feature of Subarus. These hood scoops in the rally cars literally went to nothing. I'm sure the engineers in the Subaru Prodrive team were pissed that they had a non-functional aero feature that added some drag with no benefit. Though they did install a block-off plate in the scoop so it was not sucking in air and creating low-pressure zones were hot ambient engine air could sit.
The most current versions of the Subaru rally cars used in America and built by Vermont SportsCar all use FMICs, not sure if they are V-mounted or not.
Good Information, very interesting! Thanks for sharing!
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