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Black & Green mod & maintain thread (1998 Civic DX Coupe base)
A while back MetroMPG wondered aloud on my transmission swap thread if I had a general build thread for "Black and Green." I didn't. I do now. I'll use this thread to discuss and document future mods. My one "ecomod" planned for the near future is a group of aerodynamic mods to the tail end of the car: (1) rear wheel skirts; (2) rear box void that includes a flat trunk lid spoiler and a diffuser; and (3) a bellypan for rear section and maybe middle but not front.
For the sake of documenting the car's current state, here is a list of the current mods, cut-n-past from my garage page: HYPERMILING (the best mod is the human ECU) I always use EOC and P&G on surface roads, and a mix of these and "GLEN" on the freeways. I also use MPG-optimized routes, trip combinations, and driving times as much as my commuter schedule allows. AERODYNAMIC 2.5" lawnedging airdam Side skirts v2.0 (cut rain gutter, flat black paint) Full upper grill block (v1.0) & 80% lower block (v1.2). 175mm wide tires on rear only (185s still on front). Passenger mirror replaced with internal convex. Half-moon style wheel skirts (removed). Mudflap delete. Passenger-side wiper delete (and RainX application). Radio antenna moved to dashboard. Thrush Turbo muffler (smaller than OEM, better for planned belly plan's rear diffuser). MECHANICAL/ELECTRICAL 1993 Civic CX transmission with 93,000 miles on it (installed when odo read 203,000 miles). The CX gear ratios: 3.250 (1), 1.761 (2), 1.066 (3), 0.853 (4), 0.702 (5), 3.153 (r), and 3.250 (final reduction). The DX gear ratios were: 3.250 (1), 1.782 (2), 1.172 (3), 0.909 (4), 0.702 (5), 3.153 (r), and 4.058 (final reduction). An injector kill switch Tires overinflated (60psi). An "Externally Powered Electrical System" (I plug the car in when I'm home). The set-up combines an alternator on/off switch, 7 LED brake & running lights and a H4/HB2/9003 HID kit for the headlights, a deep-cycle Odyssey PC1200 battery with metal jacket & XSP-586 SAE post adapters (installed @192K miles), and a 25-amp on-board battery charger. I've also pulled one of two 5w license plate bulbs. For notes on why the 25 amp charger is important see this post. A Warm Air Intake (WAI). And CAI/WAI manual switching ability for hottest days. 13" wheels and 175/70s on rear (replaced 14" 185/65s). NGK single-platinum spark plugs. Radiator/grill ducting (v.1.2). 6K oil change schedule. Fully synthetic Mobil 1 "Fuel Economy" 0W-30 (5w-30 for warmer seasons). Royal Purple 5w30 oil in the manual transmission. WEIGHT REDUCTION 251lbs removed (to approx 2011lbs* curb weight): 9.7lbs VX wheels on rear only (replacing 18lbs alloys), 9lb thrush muffler (replacing 18lb OEM), AC, rear seats, power steering, and numerous other things small and large. |
What all did you delete for the weight reduction? I think all I took out was te spare tire and I weighed my car at the metal scrap yard and it was 2200 pounds with a half tank of gas. That's with the hx chassis that is supposed to be 2400 pounds
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On the tail-end aero mods first on my list, I am looking for advice. I'm using Hussain Ali's paper on drag reduction as inspiration for designing the box cavity. Here an image capture of the a table of core findings: http://ecomodder.com/forum/attachmen...4&d=1370448635 I will focus on the box cavity, wheel skirts, undertray, and diffuser, since I already have the other mods. Any thoughts on this study, my possible designs, or testing? I know my car is a coupe and not a hatch like the Audi A2 Ali tested, but I plan my own ABA coasting tests with versions of the "black and green" box cavity. Here is the final version Ali tested. The diffuser is 2* instead of six because of interaction with the box cavity. http://ecomodder.com/forum/attachmen...0&d=1370575455 |
Cardboard Aided Design (diffuser mounting points)
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I have a nice pile of cardboard now--including some big sections--and black duct tape for building and testing designs. :thumbup:
I need a little help re: mounting points for a diffuser/undertray. Has anyone done this on a 6th gen Civic that might share ideas for where and how to mount the undertray? I have read brucepick's thread: http://ecomodder.com/forum/showthrea...tml#post225094. But his rear diffuser seems to be curved a bit, and I'd like it flat and adjustable in place, so I anticipate I need some way to suspend the aft edge below the bumper. In this pic and in some of the other pics attached below, you can see parts of the chassis from which I might mount rails. Any advice? http://ecomodder.com/forum/attachmen...5&d=1370525072 |
diffuser, undertray, and prototyping for testing
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The rear box cavity will need a diffuser and the diffuser will need at least a partial under tray (belly pan). So I am thinking of designs.
The first four pages of this diffuser build (and one later post with photos of the prototype) are useful: http://ecomodder.com/forum/showthrea...nel-15189.html. I want to imitate his use of togglebolts in the existing subframe, aluminum c-channels(?), and folded coroplast on the diffuser. Here is an image of a recent Civic hybrid's undertray. I like the fact that they leave space for things to heat to escape and for service access. I'm also thinking of oil drip from my ancient engine: http://ecomodder.com/forum/attachmen...3&d=1370611478 And here is my first effort at "drawing" a prototype: http://ecomodder.com/forum/attachmen...2&d=1370611450 dark green = vertical line, curved inward toward the trunk lid orange = vertical section follows tumblehome, curves to spoiler & trunklid light green = flat spoiler The goal is to allow flow to "skip" the dead air around the tail lights, create cleaner separation and a smaller wake, and therefore as I understand it produce less drag. I know any benefit will be smaller than a boat tail. I don't want a boattail because of the loss of window and trunk functionality and the increased fabrication difficulty. |
i have a pretty nice belly pan if you want to see some pics. i cut the piping off the end of my muffler and tucked it up real high so it was out of the way. it was real easy. oh and yah, i wasnt suggesting my spare tire was 200 pounds lol. that was just the only notible thing i could remmember removing. i guess i also have everything a/c removed and power steering. and my front bumper support from back when i had an inter cooler when my civic was turbocharged.
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I have begun building first version box cavity using good thick cardboard. I changed the design to a simpler box, like the one pictured in post #3. And I extended it to about 150mm instead of the 100mm size they tested. I'm skeptical this will produce results on its own that I'll be able to measure with my crude methods, but I'm willing to try it out. I'll finish it today and test it tomorrow using coasting on a hill nearby. I'll post results and photos sometime Sunday night or Monday.
[EDIT: AS OF TUESDAY (6/11) MORNING I HAVE BEEN UNABLE TO GET THE TIME DURING HOURS IN WHICH THE WEATHER CONDITIONS ON THE COURSE ARE APPROPRIATE. WEDNESDAY LOOKS GOOD. I'LL POST RESULTS AND PICS THEN.] EDIT 2: WEATHER REPORT CHANGED (6/12) FROM LITTLE WIND TO 8-10MPH WIND ... MIGHT HAVE TO WAIT DAYS, JUDGING FROM WEATHER FORECASTING. |
http://i137.photobucket.com/albums/q...25CF685B85.jpg http://i137.photobucket.com/albums/q...25CAC7B8AA.jpg
id suggest not using a Robert Thomas sign because he loves dead racoons. for some reason in west texas he ate 18 animals. i had to stop and zip tie it back up and there was flesh hanging out of his mouth. freaky. then he got a live skunk. that thing stunk up my car for a few months. but his results are unarguable. just got to keep him fed. http://i137.photobucket.com/albums/q...25BD4D4D52.jpg http://i137.photobucket.com/albums/q...77DFDD7DBB.jpg i started the front but hooking it under the bottom and then tieing the other end to the front sway bar. leave a big hatch for the oil plug and oil filter. http://i137.photobucket.com/albums/q...77DB74BB17.jpg the front is taped together because i didnt have any of the giant signs. just small ones. use the big 8 footers to make it all one piece. http://i137.photobucket.com/albums/q...77D6EB9EA0.jpg http://i137.photobucket.com/albums/q...77E4163942.jpg http://i137.photobucket.com/albums/q...77F1A1057E.jpg http://i137.photobucket.com/albums/q...77C7DEF2E0.jpg |
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And thanks. It looks like lowering your ride made it quite a lot easier to get around suspension elements. My testing is delayed again today... too much wind on the course (8-10mph), so I might move on to designing adjustable-angle rear diffuser prototype. The aero study I am using suggested the box cavity interacts heavily with under car flow, so diffuser is important anyway. james |
FIRST TEST RESULTS: box cavity (inconclusive)
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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: http://ecomodder.com/forum/attachmen...p;d=1373843754 http://ecomodder.com/forum/attachmen...p;d=1373843754 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. |
does your thrush muffler came with the oem routing ? or you did have to weld it or something else?
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me to its for its weight and smaller size because I want to upgrade my rear belly pan.
but I dont want to spend $$$ to have the job done. I just want to simply install it. |
"Maintain" before "mod"
I replaced the hub bearing unit on the driver side, front. Loud cabin noise is gone. And the car coasts WAY better. Seems especially notable at lower speeds, where aero is less of a drag. Psyched to return to modding now.
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Not sure how far along you are on the belly tray. Some tips.
Home.depot sells light aluminum window frames for.mesh window that make a great frameto mount your under tray. Be sure to leave plenty of.space around your exhaust, or the coroplast will eventually warp. Coroplast will.warp around the engine and tranny too. Maybe use aluminum in this area instead. I noticed.a 2-3 mpg gain overall with a belly tray. |
This is a great suggestion, thanks. I was at Harbor Freight today looking for tools and trying to learn a little. Be at Home Depot, maybe, tomorrow. I'm just at the point of buying hardware having scoped-out places to insert bolts and a general design plan. I'm possibly gonna use sheet aluminum, even though it costs a bit more (not sure how much more yet, waiting for a quote).
BTW, I posted photos of my "box cavity" prototype in post #11 (above). |
Thanks for this thread. I love the clarity and detail of your posts.
Edit: I agree about the spacing from the exhaust on the under panel. I ended up cutting 12''wide x 24''long around the catalytic converter. It seems to be getting better cooling now as there is some air flow along the exhaust, which I've found is important in warmer weather. I'm sure this has added some turbulence, but it's probably quite minimal since the mpg has been creeping up since I've done it. I think the underbelly is good for a solid 3mpg on my Festy. |
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1. Your tire inflation pressures are 15-25psi over the acceptable maximum inflation pressure limit for any 175/50/13 or 175/70/13 tire on the market. That's a blowout waiting to happen. The highest available 175/50/13 or 175/70/13 maximum pressure for any tire of the sort on the market is 44psi, fyi. 2. Your lowered suspension, despite improving your aero-capabilities make it much more likely that if you do end up in a collision, you will not survive unscathed. Your crash-bar height at the front, at the rear, and as far as the side-impact beams are concerned is now significantly lower than that of the vehicles around you. The net result is that if you have a crash, your car will effectively pass partially underneath the other car in the incident, drastically increasing the likelihood of serious injury or fatality for you and your car's other occupants. |
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If your suspension hasn't been modified, then your wheels are having similar impact on your crash-bar height.
A 175/50/13 tire should have a height of about 19.9", or more usefully, a radius of 9.95". The original wheel/tire package on your car was a 185/65/14, meaning a diameter of 23.5" (radius of 11.75"). So, what does this mean? Obviously you're playing the semantics game. OK, your suspension hasn't been modified, but you've effectively lowered your car by slightly less than 2 inches (11.75-9.95=1.8"), thus lowering your crash bar height by an equivalent amount. I'm not arguing that you're a bad driver, or that you're driving in an unsafe manner, I'm suggesting that the car itself is no longer able to withstand impacts the way it was designed to. The most likely (and problematic) impacts are the ones over which you have no control. As for the overinflation, I'm sure the subject has been discussed ad nauseum on here, so I'm sure you have a reasonable basis for your argument. My justification for saying that your 60psi over-inflation is unsafe was based on the listed maximum inflation pressures, for the tire type, size, speed-rating, and load capacity. Additionally, with a tire so over-inflated, your braking distances will be negatively impacted, as will your ability to make evasive maneuvers if necessary. Of course, some of this will be negated by the fact that you're running smaller-diameter wheels which carry less angular momentum and less lateral inertia. |
Dont know why you keep picking on California98Civic? if you browse all of the project cars on this form with your frame of mind, you're going be in for a HUGE SUPRISE.
all of the top mpg achievers on this site employ the same tactics: lowering the car, gutting the interior, over inflating tires, etc.... are you going on their threads slapping their wrists too? are these tactics safe? no they're not safe, but like California98civic says, texting or driving while on the cell phone and speeding is more dangerous to everybody on the road. |
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Jedi-sol here offers you some good advice: Quote:
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Subscribed!
There's some great info here and I can't wait to see the results of your on-going testing. My Cruze is a sedan body style as well, so your results with the box section are particularly interesting. It weighs about 1000 lbs more than your lightened Civic, so the only way it even stands a remote chance of keeping up with your car would be on the highway... around town your car must be pretty efficient! Interesting that your 5-speed VX transmission gives you 2.4% taller OD gearing than my 6-speed Eco. Your 0.702 5th and 3.250 final give you 2.2815 vs. my 0.61 6th and 3.83 final at 2.3363. The Cruze has a very short 1st gear though, kina necessary given the small 1.4L engine and relatively high curb weight. Funny that Honda learned the high gear ratio trick so long ago, and their current fleet of Civics has such short gearing... |
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james |
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P&G isn't advised with a turbo engine since shutting down under power leaves the turbo spinning at speed in a HOT housing, with no oil flow to lubricate the bearing and no coolant flow to cool the housing... not a good plan for long term reliability. :( Quote:
Now that you mention tire sizes, the Eco has a 26.3" tall tire (215/55-17), so the effective gearing is pretty tall. At 60 MPH that little turbo motor is only spinning ~1857 RPM. Quote:
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i was thinking of getting a set for my STI to help with coasting. |
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They may help at some point if you put some grease at the caliper guides and at the end of the brake pads but if the caliper piston is stuck they are worthless unless you replace the calipers. |
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Second, I know that the basics of hypermiling require a few things: smaller frontal area, less airflow under the car, narrower tires, harder tires (e.g. more overinflated tires), and less contact patch. So of course this is going to be prevalent on here. Third, and most importantly, the only reason I had a bug up my bum on this was because I couldn't square this: http://i137.photobucket.com/albums/q...77C7DEF2E0.jpg ...with your claims that you hadn't modified the suspension, and that everything was OEM up front (at least height-wise). FYI, I did see the 185/65/14s, but couldn't understand how "your" car looked so low if nothing had been changed. The problem was simple, IT WASN'T YOUR CAR! I feel like a dumbass, and I apologize for cluttering up your thread. Back to it, I'm interested to see how things go in the long haul. |
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Let us know if you come up with a definitive conclusion on those brake clips... seems like a neat mod. |
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Too much to do! |
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Burst pressures for tyres are WAY higher than 60psi - think double. Exploded tyres were typically underinflated, got too hot, and disintegrated or blew off . Quote:
So it's more of a suspension and road issue than a tyre issue. Tyres etc. are always a compromise, and as a driver, you live with that choice and compensate for it. Wether you're hypermiling or shooting for pole in F1. There's always a stickier tyre than what you're running ... or one that uses less fuel ... or lasts longer. The best tyres, the best suspension, the best brakes ... all still have their limits. The limit may be further away, but if you don't drive within the limits, you're out. So regardless, you always have to compensate one way or another, and drive within the capabilities of what you've got - and rest assured, that's what 99+% of us are all doing :) |
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I've always been surprised by how much drag there is on a car wheel. Even when it's still fairly new. They just don't roll all that freely. |
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subscribed, great thread.
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