Black & Green modding thread (1998 Civic DX Coupe base)

[California98Civic]

When the old switch failed a couple weeks ago, I decided to do something different than the shifter mounted switch.

Took a couple hours to figure out the arrangements and get proper fitting hardware from my leftovers and odd-and-ends bin, but here is my new shifter and injector cut off.

The injector toggle is mounted on my DIY center console "instrument panel." The new shifter is a primed and painted kids candy box of some kind that I found in the street a couple years ago. It is made of really strong plastic and had a "gear-shifter-ready" ergonomic shape. Only purchase was the $3.50 for the toggle.

[aerohead]

Originally Posted by California98Civic

Not surprisingly, there seems to be no measurable benefit or loss to FE from the "rear box cavity" design I tested this morning. This because the benefits would be small and the instruments and my approach to the test probably created too much noise in the "data."

The mod prototype (it's ugly):

I created a box like the one in post #3 above that has a flat decklid spoiler at the top, parallel sides extending downward along the trunk seam to a horizontal bottom midway across the rear bumper. All of it extending about 150mm off the back of the vehicle. Rigid. Stable. Attached with copious amounts of black duct tape. Pics:





Course and conditions:

I picked a 1 mile long hill, uninterrupted by lights and without heavily traffic.

The last "weather underground" report Friday night predicted wind at 2mph out of the SSE at 5am, shifting to 1 mph from the S by 8am. Temps were expected to be 52F at 5am and rising to 59F by 8am. Complete cloud cover throughout the morning.

Method/approach:

I drove the car 10 miles to the site to warm the tires and engine. I arrived at about 6am and was done by 740am, after which I went out for coffee with some friends. I used the Ultra Gauge speed sensor reading instead of the OEM gauge. I got the car to 20 mph or as close as possible--evenly coasting--by the time I crossed a specific crosswalk line on the road at the very top of the hill. Then I coasted, braking at the bottom, ahead of a light that was nearly always red.

I aborted any run where I could not get an consistent coasting speed at or as near as possible to 20.9 by the time I crossed the start line. The ultra gauge, I did not realize, seems precise but it not. Its speed readings jump by increments of about .7mph, which is more than 1% of the top speeds I achieved on the course.

To compensate for the rising temps and the effect they might have my speeds, I started without the box cavity attached for three runs (cooler ambient temps of maybe 52F), did six straight with the box cavity attached (presumably slightly warmer ambient temps) and then three more without the box cavity (during presumably warmest ambient temps of possibly 59F).

Results:

Numbers are speeds in mph at four different points coasting down the hill

A1 (no mod):
20.9 35.7 56.7 58.7 = +37.8
20.9 35.7 56.7 59.3 = +38.4
20.2 35.1 56.0 58.7 = +38.5

B (mod):
20.9 35.7 57.3 59.3 = +38.4
21.6 36.4 57.3 59.3 = +37.7
20.2 35.1 56.7 58.7 = +38.5

20.9 35.7 56.7 59.3 = +38.4
21.6 36.4 56.7 59.3 = +37.7
20.9 35.7 56.7 59.3 = +38.4

A2 (no mod):
21.6 36.4 57.3 59.3 = +37.7
20.9 36.4 57.3 59.3 = +38.4
20.9 35.7 56.7 59.3 = +38.4

Average final speeds: A (59.1) B (59.2)
Average speed change start/finish: A (+38.183mph) B (+38.183mph)

Conclusion:

Obviously, there was no change distinguishable from noise created by imprecision in the testing methods and gauges. The results are equivocal. Starting from a still position and using a GPS device would lessen the "noise." Hussain Ali's study of the box cavity I mentioned above showed a very small benefit, anyway. And a study by Adrian Gaylard et al. has suggested the benefits were smaller for a coupe style body like mine. Ali also suggests that the diffuser and its angle mattered a lot.

Next Steps

Leave this mod idea behind. Do underbody panels, an adjustable angle diffuser, and wheel well skirts next. Get a GPS and do any future testing from a standing position. Maybe I'll redo this test later in the summer. A comparison before and after additional aeromods might be fun.

My thought about the box-cavity is that the sides should follow the outer contour (run parallel but at a smaller scale) of the CIVIC's sides, and should extend as far,say as much as Mair's boat tail contour for the same distance back,or else the trailing edge just won't capture the locked-vortex which allows the cavity to operate.
Here's an abbreviated 'Template' based upon Mair's wind tunnel model

You'd have to find where your plan-view taper begins,then morph out from that point matching the CIVIC's width to the Mair 'Template.'

[Daox]

You're using a toggle switch for your kill switch? How do you like it?

[California98Civic]

Originally Posted by Daox

You're using a toggle switch for your kill switch? How do you like it?

It's okay. I know I'll get more used to it over time. The problem with the shifter mounted stuff is the stress on the wires and the periodic fails I had. I also wanted a smaller shifter so I could see gauges. Lastly, I was reluctant to cut into the OEM plastics and place it beside my seat. If I hate this set-up I can change it, no problem, and not have a hole in the dash.

Reinstalled the airdam before sunset. I got the mountings better placed and tighter, and the car seems to scrape less, even though the airdam itself is the exact size and shape of the previous.



AEROHEAD: thanks for your comments on the box cavity. Someday I might return to that idea, but right now, I'm ashamed to say, I have a half finished undertray and diffuser hanging under the car and hanging-out in my garage! Just. Too. Busy.

[jedi_sol]

Originally Posted by California98Civic

With my MPG down under 60, I am finally making time to restore my injector kill switch and front airdam (maybe wheel skirts too). In warm weather like this, I should be scoring 5-8 mpg higher without even trying hard. Instead I am working hard to stay close to 60mpg. At least I have a good indicator of the significance of these three mods.

Even though the weather is warm for this time of year, the low mpg is most likely the winter blend?

[jedi_sol]

Have you considered using a brake switch as the kill switch? I use it on my sti, and works like a charm. Press to kill, release and the car is primed to bump start.

since it's used for braking, I'm sure it's designed to last for thousands of pushes.

[Chrysler kid]

I always figured the best spot for a kill switch would be on the center console right below the arm rest where those factory blank panels are (where the parking pole switch on European market civics are)

He was breaking the switch because of its movement on the shifter. I know it's not what you ment but a foot operated switch sounds intriguing too. Put a bicycle shoe on the gas pedal so you can lift up the pedal to engage a switch that kills the injectors


Also had a thought the other day, I wonder if you could use the window switch panel from a civic sedan and wire the two switches for the back window to function as an auxiliary switch. You have crank windows so technically you just need to cut the hole for the window crank on a power window panel for a coupe and you would have 4 switches on the door you could use for anything you wanted

On reducing drag the rear trunk area of the civic is deformed and massive compared to that tiny spare. Underbelly pan under the trunk combined with your aero spoiler would have a much greater effect on mileage.

[California98Civic]

I did not consider a brake switch. But it makes sense. I just was not aware of them. It's a momentary switch, I would guess, so I probably would have decided against it. One thing I like about the on/off style is you don't have to hold it down for that split second, which sometimes turns into an entire second. My hands are freer, even though I need to flip it back to on before I bump it.

One thought I wondered about for a second was a left foot activated switch, like my 74 Olds Delta 88 had for the highbeam headlights.

On the fuel mix... I don't think we're on winter fuel yet, are we? Took a run up the 5 to Santa Ana and Orange this morning, even without my wheel skirts back on yet, and even while doing relatively little P&G, I averaged about 65 mpg. Given what i saw the last two weeks without the airdam, i would bet Id be closer to 60 or 61 if I had not reinstalled the airdam yesterday. Amazing what a little lawn edging can do!

James

[California98Civic]

Here is the test... first stop on the test run will be a hardware store for more duct tape.

[Chrysler kid]

I do not care for duct tape, the design looks great though

A secondary wheel arch, or mounting points to the fender lip would seem like a more professional solution. I'm thinking L shaped brackets along the front with snap lock fittings using a cupboard hinge at the top