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Old 01-29-2014, 04:50 PM   #1 (permalink)
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2000 Honda Insight aero tail extension: made from spare bumper, 5% MPG gain

Second project I'm posting on behalf of a longstanding 'lurker' member, with permission (see also his aeromodded/mechanically modded 65 mpg Austin Healey Sprite.)

It's another Insight tail, made by adding on an additional Insight bumper cover, cut and tapered:







"Crude" says the builder, but effective:
  • I took a second bumper and decreased the tail to .55 of standard (original) area.
  • 16" extension using a shortened and narrowed g1 bumper and sheet lexan, plus sheet metal screws.
  • In 7 trips of my 18 mile test course it gained from 71 to 74.8 mpg (about 5%) at 55 MPH on cruise control and 40 degree F temp.
Another Insight tail joins the fleet!

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Old 01-29-2014, 09:26 PM   #2 (permalink)
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Love to see his long term results on mileage.
I would like to say it looks good but

I wonder how Honda decided where to cut the rear end of the car off at.
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Old 01-30-2014, 12:14 PM   #3 (permalink)
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Fascinating project.

I've certainly seen worse grafting projects.

http://forums.pelicanparts.com/off-t...ures-1262.html
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Old 01-30-2014, 12:20 PM   #4 (permalink)
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Hi Ron22-l thought of that also, but when I read about them adding a short (16") tail on the GM-EV1 to gain speed, and they were successful, I decided to try it. I do not have to face the real world because of being retired 21 years, and buying groceries or a beer run is the only required driving. When the weather gets warmer, longer excursions are in order, and I will report.
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Old 01-30-2014, 01:37 PM   #5 (permalink)
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xpedro01 is that you car?
Like you I gave up a long time ago what other people thing.
Keep up the work and keep up informed.
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Old 01-30-2014, 02:47 PM   #6 (permalink)
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Yes Ron22, this mod was made in the last month. Windydrew is preparing an IMAC&C mod to install and while waiting l made this 16" extension. So far, it is meeting expectations.

Last edited by xpedro01; 02-11-2014 at 12:34 PM..
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Old 01-30-2014, 03:01 PM   #7 (permalink)
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Quote:
Originally Posted by xpedro01 View Post
when I read about them adding a short (16") tail on the GM-EV1 to gain speed, and they were successful, I decided to try it.
I think I know the short tail of which you speak...

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Old 02-01-2014, 02:43 PM   #8 (permalink)
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74.8 mpg = Cd 0.223

I took xpedro01's MPG numbers and did a quick napkin calc.,yielding Cd 0.223 for the boat tail modification,using Honda's published Cd 0.25 for the 'naked' car.
Fun! Beer and groceries just got cheaper.
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Old 02-01-2014, 03:29 PM   #9 (permalink)
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GM Impact/EV1 LSR

Goro Tamai had some numbers for GM's land speed record car in an endnote on page 19.
In 1999 GM reported Cd 0.197 for Impact/EV1.
For the speed record they:
*deleted wipers
*covered over the cowl area
*deleted the side-view mirrors
*created fairings at the lower front tire leading edge
*installed flat aluminum wheel disks
*added the 16-inch "Yellow Ferret" boat tail
*taped over body gaps
*lowered the car 40 mm (1.57")
*installed Michelin speed-rated tires
*the nose fascia was devoid of any openings
--------------------------------------------------------------------------
Goro Tamai reported that GM's team got the Cd to 0.14 (if frontal area was considered a constant).That could mean Cd 0.149 if considering 'points.'
Since the frontal area was impacted by the mirror delete and lowering,the Cd was probably a bit higher.
By itself,the tail pushed top speed from 178 mph,to 183.From Hucho's drag/speed relationship this would roughly equate to a 8.4% drag reduction.
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Old 02-01-2014, 03:43 PM   #10 (permalink)
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Aerohead--great minds must run in the same gutter. Using ecomodders very good calculater l took standard numbers for the insight + ones l could change, till they matched my before conditions. Then after the installation and testing 4- 18 mile runs, l changed only cd in the info till it matched my mileage for 55MPH with cruise control and 40 degrees(same as before), and it just about agreed with your number. Thanks for verifying.

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