In order to make the Civic a more perfect family car, it needs better aerodynamics, more cargo space (and an improvement of ICE efficiency by some method). An Aero Hitch Box and other mods will improve aerodynamics and increase cargo space.
Aero Hitch Box status
It's on the road!
Preliminary tuft testing (and preliminary MPG numbers) indicate rather crummy performance. Air flows upward between the box and the car and creates a substantial vortex along the rear windshield. Detachment along the sides is turbulent and does not reattach well. Shouldn't be too hard to fix though. Tuft it to death!
- (Better) tuft testing.
- Adaptation for 1-person installation and removal from the car.
- A-B-A testing, preferably using coast-down method
This thread will probably mostly be about my forthcoming hitch-mounted cargo box boat-tail. Okay, not exactly the first time we've seen the general idea, but maybe the first project thread applicable to a sedan. Also I'll have some brief descriptions of other mods on our 97 family-of-four Civic, and of course results.
Getting right down to it; my plan for the Aero Hitch Box (avoiding the 'copyrighted' name
Green - the part I'm fabricating. (Black is the hitch receiver on the car.) I'm thinking strip reinforced aluminum sheet, rivet construction. However, that method hasn't got the wife test green light yet. I could probably get it done just as fast in plywood, plus foam/bondo, and it would be more likely to pass the wife test that way, but I expect that would be heavier and less durable.
I've sized the space from the bumper to the front of the box to give enough clearance for the trunk to open, plus a half-inch for good measure.
I'm probably going to want to put a caster on the main steel post that it will be on to minimize damage in the event of a departure angle violation, but I probably need to experiment in my driveway.
Now, I see some aerodynamic gaps here to fill. The only question is how far do I need to go to get good results? I expect this to require some testing to be sure about it.
Possible Gap Fill Remedies
Opaque Half-Kammback (orange) with clear plastic side fillers (blue):
Full-Kammback with hinged window (or louvers):
All the remedies attach to the car, so you can imagine with the aero box off the car roughly fits a Prius profile with a full Kammback.
Any thoughts so far?
Hoping to get this done before spring, but you never know with me.
Random background notes, if you want them:
- Hypermiling by itself has phenomenal ROI, but I find it relatively incompatible with long-haul family travel.
- A high goal that I have on my mind is MPG retrofit of numerous existing vehicles; I always have an eye out for mass production and market compatibility, although I kind of doubt that I'm the right guy to pull the trigger on this type of fabrication, even if I had the right project for it.
- I just got my long-haul family MPG up from about 36 to 42. The primary factor was P&G, which I had never done on a long-haul in this car before. That's 42 MPG at 70+ MPH in <35F with minimal aero mods. Not bad, eh? The other project I've got kicking around in my mind, which is more closely matched to my skill set for production purposes, is a P&G cruise control. I'm still in an info gathering stage though.
I will be editing this post for current status and index.