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Old 06-29-2010, 10:58 PM   #1 (permalink)
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Where to start... should I just drive in reverse?

So this is what I'm dealing with: (not my car, but the same shape, minus the hood scoop)


Short of rebuilding the back end, or seeing if I can get my engine turning backwards, what can be done? Would some sort of spoiler/wing forcing some air down the backend be helpful or just more drag? I have seen very little about any type of spoiler on ecomodder, which makes me think they are bogus for FE. But it seems like it could help in theory, and for the price of an afternoon, and 3 feet of 2X6....

Any suggestions would be much appreciated.


Last edited by Dr. Jerryrigger; 06-29-2010 at 10:59 PM.. Reason: a : next to a ( truns into a emodicon, who knew?
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Old 06-30-2010, 12:27 AM   #2 (permalink)
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Those are oversized aftermarket wheels and brakes, right? I hope yours have better aero than that.

The idea of a car with better aero backwards than forwards is amusing, but lots of wagons give that impression. Still, you wouldn't want a rear-engined car with four feet of cargo space in front of the dashboard, so that's why it's shape isn't the best aero.

Your hatch has a really nifty shape that you don't see much of anymore. Check out what Piwoslaw and MetroMPG have done with their similar-shaped hatches. I think it would bring excellent aerodynamic results with little impact on usability.
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Old 06-30-2010, 01:12 AM   #3 (permalink)
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You could definitely build a good kammback on that.



Add an undertray and an upper grille block, and that should be good.

Stock, you have a Cd of about .31, which isn't too bad. A few tweaks and you could have a really slick car.
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Old 06-30-2010, 02:46 AM   #4 (permalink)
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That's a nice car, don't ugly it up with boattails and fins.
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Old 06-30-2010, 07:38 AM   #5 (permalink)
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That's not his exact car, just the same model. You can see the STi brakes poking out from behind the wheels. I doubt he'd be on this site if he had that exact car (:

The modded picture is pretty close to what I've got on mine, and it seems to be the 'low hanging fruit'. The grillblock/airdam up front, then the smooth wheels. I've also lobbed the mirrors off because they're truck-sized and account for nearly 1 mpg each at highway speed. Before doing anything I'd suggest getting a scangauge or some other instrumentation and seeing what works and getting your driving style up (: Otherwise I'd suggest the first aero mod be a grillblock. It's easy to know if you screw that up.
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Old 06-30-2010, 08:58 AM   #6 (permalink)
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You're right on with driving in reverse:
Teardrop aerodynamics... in reverse!

With your hatch sloped like that there is a lot of room for a Kammback. My roof extension + rear wheel skirts reduced fuel consumption by 8% at 100km/h (60mph). Your Kammy could be longer than mine, reducing the turbulent wake even more. Have a look at my modding thread for details.

Brucey is right: It's easiest to start with a grille block.
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Old 06-30-2010, 01:20 PM   #7 (permalink)
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Thanks for all the suggestions!

AeroModder,
Thanks. I was trying to find my cars stock Cd for some time. I like the pic! I was also considering pre and post wheel flap things to make them moor of a tear drop.

winkosmosis,
I would agree if my car looked this nice. Mine has more dents, sloppy bondo patches, and is painted about 1/3 in primer.

brucey,
The grill block is number one on my list, as it is so simple, I'd like to do a belly plate too, but a nice strong one, for the off roading that seems to happen now and them... Though it's working agest me for aero, I'd really like to lift it 2" or so and put some larger tires on it someday....
Have you found noticeable benefit from the hubcaps? It seems like a more pricey mod, for relatively little surface.
A scan gauge is high on my list, once I get a job.... the big thing holding be back from that, is that i want a fancy one like dash dyno with data logging, and that is way out of my price range right now.

Piwoslaw,
8%, that's really impressive. And it looks really slick too!



So I will start with a grill block. It seems rather hard to mess it up.
The Kammback will take a little more planing, and playing around, which will happen in time...
I've got to figure out some pic hosting site so I can get some real pics of my car...
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Old 06-30-2010, 02:12 PM   #8 (permalink)
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The hubcaps I got are just tape and spray paint. Quicker payback (: Good for 3.5% from my own A/B testing.



I've also got a skid plate I put up, probably 50$ in materials and sweat equity.



I don't know how much it's hurting/helping, but I drive on my family's farm a lot and have ran over a lot of stuff that's hidden in the grass. So the piece of mind helps. (:
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Old 06-30-2010, 05:16 PM   #9 (permalink)
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where

There are a few schools of thought.
You could mimic the Ford Probe-IV concentrating on mostly the fore-body and go for CD 0.157.
You could mimic the Probe-V double-ended approach and go for Cd 0.13.
Or go for the Jaray pumpkin seed and shoot for Cd 0.09.
The 1934 Chrysler Airflow thread will give you an idea about what tail mods can provide,however you accomplished.
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Old 07-01-2010, 05:00 AM   #10 (permalink)
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0.31 cd is a good start for a vehicle of that shape - ironically that's no different from a good three-box body sedan! The Subaru Legacy had 0.34 or similar?

At least start with grille block... this should be the default first mod, nice and easy!
Remove roof rack... easy also.

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