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Old 12-22-2017, 06:33 AM   #1 (permalink)
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Civic sedan rear spoiler

So I've been thinking about splashing some cash on a rear spoiler to reduce drag for a while. More recently I started thinking it would give the car a more balanced look, this was especially after i saw a civic like mine with a big spoiler, see pic.

So i spent $40 on a suitable spoiler, I spent ages hunting for it btw. I never get my money back on it but may increase the value of my car since it becomes more unique and desirable lol

The main purpose I hope will be to reduce drag, if it increases drag, I should see it on my mpguino, then ill take it off.

What do you guys think of it?

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Old 12-22-2017, 06:35 AM   #2 (permalink)
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Talking

This one is my car [attach]Click image for larger version

Name:	IMG_20171222_145547.jpg
Views:	42
Size:	88.8 KB
ID:	23212

This is the one that inspired me somewhat Click image for larger version

Name:	IMG_20171216_085625.jpg
Views:	29
Size:	64.3 KB
ID:	23213[/attach]
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Old 12-22-2017, 06:39 AM   #3 (permalink)
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As you can see it is only sitting on the trunk,
it'll need some custom mounting plates to fit nicely Click image for larger version

Name:	IMG_20171222_145535.jpg
Views:	26
Size:	85.2 KB
ID:	23214
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Old 12-22-2017, 09:28 AM   #4 (permalink)
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For fuel economy think differently. Instead of lift reduction (which is what race spoilers are about), which induces drag, try for drag reduction. Go for flat spoilers or trip spoilers like you see on fuel economy cars, such as the Prius or Civic hybrid. Like this, maybe: https://www.autocar.co.uk/sites/auto...?itok=Dq-1iGJ7
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Old 12-22-2017, 03:49 PM   #5 (permalink)
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Looks nice, but I'll be surprised if the effect of the spoiler shows up definitively on the MPGuino in day to day use.

I think the best way to try testing this would be repeated sets of coastdown tests: more controlled, more sensitive to small changes.

I know a guy with a 2006 Civic who took his rear spoiler off (very similar to yours) for drag reduction. Who's right? Who knows!

I told him to get a 2006 Civic Hybrid style decklid lip spoiler.
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Old 12-22-2017, 04:36 PM   #6 (permalink)
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Which purpose?

Fuel Economy = Small spoiler; something to minimize airflow disruption.

Down Force = Large spoiler; something to convert horizontal airflow into downward force.
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Old 12-22-2017, 09:06 PM   #7 (permalink)
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The top of the wingy-thingy is about right (~12), the tumble-home of the sides is good.

I'd stretch a black mesh over the opening to make a perforated base plate. Easily undone for A-B-A testing.
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Old 12-23-2017, 02:52 PM   #8 (permalink)
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this one

Quote:
Originally Posted by D15r View Post
This one is my car [attach]Attachment 23212

This is the one that inspired me somewhat Attachment 23213[/attach]
With so very little actual data in the public domain,we have only scant information from which to predict your wings performance.
When KAMIE introduced the first commercial add-on spoiler,in the early 1980s,it was simply an non-ventilated upswept kicker style device.
During the development of the 1982 Pontiac Trans AM and Camaro,the aerodynamicist involved commented that the simple upswept spoiler (as would be used on the Camaro) was superior to the basket-handle,wing-type which ended up on the Firebird.Pontiac chose the latter for it's 'look',rather than it's performance.
Recent production cars chosen for Bonneville speed records (Fusion,Sonic,Jetta) have all chosen non-aspirated spoilers.There's probably a lesson for us there.
Your wing might have an advantage as to rear vision when backing the car into a parallel parking space.
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Old 12-23-2017, 03:35 PM   #9 (permalink)
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Quote:
Originally Posted by freebeard View Post
The top of the wingy-thingy is about right (~12), the tumble-home of the sides is good.

I'd stretch a black mesh over the opening to make a perforated base plate. Easily undone for A-B-A testing.
So you mean close of the bottom, underneath the top surface of the spoiler, to prevent air exiting thereby causing a high pressure area that the air stream sees as similar to being a kamm back of 12 degrees?

Last edited by D15r; 12-23-2017 at 04:21 PM..
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Old 12-23-2017, 03:39 PM   #10 (permalink)
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Quote:
Originally Posted by MetroMPG View Post
Looks nice, but I'll be surprised if the effect of the spoiler shows up definitively on the MPGuino in day to day use.

I think the best way to try testing this would be repeated sets of coastdown tests: more controlled, more sensitive to small changes.

I know a guy with a 2006 Civic who took his rear spoiler off (very similar to yours) for drag reduction. Who's right? Who knows!

I told him to get a 2006 Civic Hybrid style decklid lip spoiler.
Ikr I'll see what happens, so many variables.

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