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a_not_fast_04_Wagon

Full length underbody tray

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Thinking about having a full length underbody tray made and I was wondering if anybody has any info on how effective it is for fuel economy and slipstream etc.

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I think it does f*ck all unless you're full racecar and the car is low as a low low thing, and you're driving on a race-track smooth surface. Otherwise the turbulence under the car is a joke anyway. I think for fuel economy you would spend more on making up a flat bottom than you would ever save in gas.

 

EDIT: This also completely throws out the window that Subaru spent a whole pissload of R&D on designing a bunch of aero for your car already; for example the gearbox tunnel creates a low-pressure area at the rear of the engine bay that is intended to draw air down through the intercooler and past the turbo; if you put a full under-car tray on this would probably become a high-pressure zone instead due to all the air coming in through the bonnet scoop having nowhere to go.

 

Amateur aero is more or less a complete waste of time on the road.

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Lots of cars have them... I think they are there to keep road dirt and water out of the engine bay, rather than for any aero effect.

 

 

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the idea is to have them lead to a defuser out the back, defuser needs smooth airflow to work correctly. Car needs to be low to make them work. better off getting a bigger lower front lip. not the stick on foam s*** though.

Or on rally cars stop the stones eating everything.

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On 27/05/2020 at 6:06 PM, Loren said:

Lots of cars have them... I think they are there to keep road dirt and water out of the engine bay, rather than for any aero effect.

 

 

 

Not the full length of the car, though...

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Posted (edited)
3 hours ago, boon said:

i

Not the full length of the car, though...

 

I thought he meant just the engine bay... not sure why... but yeah... for time attack type vehicles they are probably good, as long as you have a good aero guy :)

Edited by Loren
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If you have a hood scoop like Subaru you should have a tray as far back as the scoop to create a vacuum to draw more air through intercooler and radiator. 

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My Sw20 had it right up to the frunk firewall. Probably to compliment its high level drag coefficient? 

 

Shed built shoestring budget aero may work with no R&D, but usually just more bling?

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