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Old 04-29-2014, 07:57 AM   #211 (permalink)
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Al the Third, year four - '13 Honda Fit Base
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Nine gallons to recover is cheaper than making a new one from scratch.


Originally Posted by sheepdog44 View Post
Transmission type Efficiency
Manual neutral engine off.100% @MPG <----- Fun Fact.
Manual 1:1 gear ratio .......98%
CVT belt ............................88%
Automatic .........................86%

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Old 04-29-2014, 08:05 AM   #212 (permalink)
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Black and Green - '98 Honda Civic DX Coupe
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Originally Posted by Fat Charlie View Post
Nine gallons to recover is cheaper than making a new one from scratch.
^ agreed. Driving any car means mishaps, so once they happen, figure out the best next step and move on. Looking forward to further reports.
See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.

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Old 04-29-2014, 02:40 PM   #213 (permalink)
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It was a mistake to walk away from something I had made with my hands, when so much of it was salvageable. But that wasn't clear until I had worked out what the solution to the side-wind would look like.
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Old 05-27-2014, 07:13 PM   #214 (permalink)
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Valerie - '03 Honda Civic DX
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You and this project have been an inspiration to me about the future of my car. I'm glad that nothing was seriously damaged. Success is at the end of a road of many failures. I can't wait to see further improvements!

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Old 05-27-2014, 11:54 PM   #215 (permalink)
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Plus 1 for tie downs+duck tape!
Utilizing this for experimental spoiler, and a host to the Exploding Kamm klub

Also, skool of hard knocks is the best as much as it pains us, we all taste it until we find something better! keep up the work
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
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Old 05-28-2014, 02:19 AM   #216 (permalink)
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Lots of really cool ideas and execution! Magnets instead of drilling the roof, something I'm not sure I would ever have thought of. Also, you linked a single magnet but said you somehow bought them in pairs, here is the listing for the opposite-polarity pairs, for anyone interested:

K&J Magnetics - Products

The trunk-moved kammback is how I was thinking of doing it on my first car but never did; your execution is both proof-of-concept and encouragement for my current 05 Accord. Great idea with the magnetic fabric-mat material, very clever on the hinged attachment for the hitch-box. And I highly approve of sheet metal. Your fabrication skills (and tool selection)(and cad/simulation knowledge) are definitely something for me to aspire towards.
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Old 05-29-2014, 11:36 AM   #217 (permalink)
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Awesome project! I learned quite a bit reading through all this!
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Old 12-26-2014, 10:07 PM   #218 (permalink)
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Quick updates

Some quick updates:

I'm contemplating moving overseas for a few years for a job opportunity. If so, most likely the removable mods will go into storage and I'll sell the car.

Magnetic attachment of anything to the outside of a car is no good, according to Utah inspections. The Kammback has been shelved since June.

The AHB latch was left open due to user error and the lid flipped open on the road, damaging some sheet metal. I've repaired it, but haven't added a secondary safety feature yet. See the next post.

I faced a headwind during a trip recently. My best estimates are 28-30 MPG, level ground, ~72 MPH ground speed, 25-35 MPH headwind, ~45 MPH gusts. So that would roughly be my MPG at around 100-105 MPH, if I had a suitable gear. Here are my best guesses on the car's performance parameters right now:
Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com
Cd: 0.30
Crr: 0.12
(Maybe higher Crr right now: we're in winter tire season, they might be a bit higher than the all-seasons. The Crr end of my coast-downs has registered at around 0.12 with the (crappy) Les Schwab all-seasons. So I should be able to reach 45-50 MPG at PSL (neutral wind condition) just by getting some decent LRR all-season tires... on paper.)

So the project overall is somewhat successful: I can get mid 30's MPG trip average in very unfavorable conditions without sacrificing speed, with loads of storage volume. And the tail has proven it's ability to hinge on contact, avoiding damage.

I think the underbody is where I've primarily failed aerodynamically on this project, so far. It looks awful and so far I've left it untreated.

Last edited by christofoo; 12-26-2014 at 10:35 PM..
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Old 12-26-2014, 10:34 PM   #219 (permalink)
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Damage and repair of the AHB (Aero Hitch Box)

I had a bad feeling about letting my wife use the car and AHB without me around. In hindsight, I tried to train her on the latch, but didn't put any emphasis on how unfreindly it was. It was possible to get the feeling it was engaged, when it wasn't. So I'm sure it's not really her fault.

In any case, she thinks she was going about 30 MPH when it flipped up and hurt itself. The lid didn't detach, but it bent up the sheet metal in the aft and tore out a number of rivets.

Snipped out the damaged sheet.

Healed it with a new sheet.

And redid the hinges. I hated the piano hinge.

(The hinge actually feeds through the sheet metal's crease, so it's aesthetically pleasing without a big sacrifice in stiffness. But I still sealed it up around the hinge. I liked the way this turned out, but it would still damage itself if it flips up again, most likely. Actually, maybe if I put a foam pad in the right place to absorb the shock, I might be able to engineer it to survive a blow over.)

If I was smart I would make sure to add a secondary latch before I use this too many more times... though the lid actually fits better now, so the latch is less error prone.
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Old 12-27-2014, 07:33 AM   #220 (permalink)
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I'm sort of following in your footsteps with an 8th gen '07 Civic sedan.

Kammback is nearly done. Starting on the tail extension this weekend. Construction materials and techniques not nearly as nice as yours. Oh, and ZERO added utility/storage.

Ps.. good luck on the job prospect.

Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown

has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
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