SakoTGrimes Posted February 2, 2010 Share Posted February 2, 2010 Somehow, for some reason, there doesn't seem to be a thread devoted to aerodynamics.... That I could find anyway.... So, let this be it. Since I have become obsessed with fuel economy (57.51mpg in the Tercel baby!) I would like to experiment with modifying the EA82 wagon, which appears to be only slightly slippery than a Volvo brick wagon. Currently I am at 29.5mpg in the wagon..... not bad by most people's standards, but I'd like 40 a lot better. I know it can be done. I will post any results here when I get the numbers. For now, does any body know the Coefficient of Drag of an EA82 wagon? Can't find it on the net, since nobody seems interested in it : ( Quote Link to comment Share on other sites More sharing options...
eulogious Posted February 2, 2010 Share Posted February 2, 2010 S For now, does any body know the Coefficient of Drag of an EA82 wagon? Look up the coefficient of a barn in a wind storm, and I think they are about the same On a serious note, the first thing that I would do is tidy up the underside of the car. Make the exhaust closer to the body, add some sheet metal to smoothen the underside out to try to make it better, that sort of thing. I don't really see what you can do with the rest of it, it's seriously a shoe box with wheels, so it's going to be hard to make it have less drag. Sounds like a good idea and I would love to see a wagon getting 40 mpg. That would be sweet. Until then my shoe box and I will rock the 25 mpg Keep us updated on your progress with this, sounds like a fun project! Quote Link to comment Share on other sites More sharing options...
rpholz Posted February 2, 2010 Share Posted February 2, 2010 (edited) i say ditch it for a 2wd n/a XT seriously i get like 36 or so mpg. i image i could improve on that but i'm pleases with it so far. i am interested in seeing how much you get outta wagon, i say, more power to ya! and drag coefficient idk Google it, cause i stumbled a crossed a page that listed like every car ever. it was crazy I'll try to find it again for ya and XT= .29 (win!) lol Edited February 2, 2010 by rpholz Quote Link to comment Share on other sites More sharing options...
idosubaru Posted February 2, 2010 Share Posted February 2, 2010 (edited) lowering it might help and roof racks are bad. the XT6 can get a couple mpg more on the highway with larger wheel/tire combo's, but it's got the hp/torque to push them. skinnier tires would help but decrease handling. the more stopping/climbing you do - the more weight will matter. on highway trips my XT6's and XT's would get the exact same mileage if i was by myself or loaded with a couple hundred pounds of gear. Look up the coefficient of a barn in a wind storm, and I think they are about the same i seriously at that, thanks! an 88-91 XT FWD manual trans can get 40 mpg. doing 70 mph between MD and GA I did it for years in my 88. that was back in the early 90's. Edited February 2, 2010 by grossgary Quote Link to comment Share on other sites More sharing options...
bheinen74 Posted February 2, 2010 Share Posted February 2, 2010 (edited) need to swap an xt front clip to the ea82 wago, and then make a huge long tail fin out the back rear like a teardrop shape cone off the back. cover the rear wheel wells with fenders from a Honda Insight put aluminum pizza pans on the front rims. Its easy as pie. low rolling resistant tires aired to 50psi gut the weight, and underbody shield, lowered of course. easy, dont forget new plugs, wires, air filter, fuel filters, and the best tuneup you can give it, and a good grade of Amoco Ultimate or Sunoco premium. Use full synthetics on oil, that reduces friction internally. maybe port and polished heads and a better cam, ditch all unneccessary electronics, they draw power from the alternator (no radio) Edited February 2, 2010 by bheinen74 Quote Link to comment Share on other sites More sharing options...
Txakura Posted February 2, 2010 Share Posted February 2, 2010 the mirrors cause a lot of drag... no easy solution there (still laughing at the barn joke) Quote Link to comment Share on other sites More sharing options...
dhise Posted February 2, 2010 Share Posted February 2, 2010 A FWD wagon should get close to 40 mpg with a light foot. 37 mpg is the best I have done driving 55 on the highway with everyone honking and flipping me off, but it does save money. If I could drive 50 on the highway I could get even better mileage. Slowing down is the next best thing to aerodynamic mods. Quote Link to comment Share on other sites More sharing options...
Markus56 Posted February 3, 2010 Share Posted February 3, 2010 +1 on the XT. Driving 70 miles everyday in my 4wd XT get me an average of 30 mpg. Quote Link to comment Share on other sites More sharing options...
derburger Posted February 3, 2010 Share Posted February 3, 2010 My turbo 4wd XT gets about 28-30mpg at 70, and lower 20s in city driving. I wonder what an XT would be like with the usual aerodynamic mods but having a VW diesel swapped in. The diesel may fit with some "minor" hood modifications. Quote Link to comment Share on other sites More sharing options...
Scoobywagon Posted February 3, 2010 Share Posted February 3, 2010 Ok...Coefficient of Drag (Cd) can be calculated as follows: Cd = (Fd) / (1/2*p*v^2*A) where Fd is the drag force applied to the vehicle, p is the mass density of the fluid in which the vehicle is operating (air is a fluid), v is speed of the vehicle relative to the air and A is the frontal area of the vehicle. Drag force is closely related, so the formula for that is nearly identical which makes solving them simultaneously a bit difficult. So I did a little searching. I managed to find a CdA specification for a 91 Legacy. That should be fairly close to GL wagon. That'll be 6.81 sqft. For the sake of simplicity we'll convert to metric. 6.81 sqft = .632 square meters. So we go back to the drag force equation. Fd = .5 * p * v^2 * CdA = .5 * p * v^2 * .632 The mass density of air at 70 degrees and sea level is 1.204 kg/m^2. Fd = .5 * 1.204 * v^2 *.632 Again, for simplicity, we'll assume that we've got no wind and no turbulence. We'll also assume that you are driving 60 mph. That converts to 26.8224 meters per second. Fd = .5 * 1.204 * 26.8224 *26.8224 * 0.632 = 273.721 Now we can convert that all back to get just the Cd. Cd = (273.721) / (.5 * 1.204 *26.8224 *26.8224 * A) A little more searching and the frontal area of an L-body car is 2.33 square meters. So... Cd = (273.721) / (.5 * 1.204 *26.8224 *26.8224 * 2.33) = 0.27 Probably not astoundingly accurate, but close enough. Quote Link to comment Share on other sites More sharing options...
SakoTGrimes Posted February 3, 2010 Author Share Posted February 3, 2010 I see I'm not the only ecomodder forum user here Yes, XTs pwn wagons in the cda department, but epically fail when it comes to hauling Christmas trees. One day I'll get one though to mess with. Mirrors are an easy fix. Get rid of 'em. For now my passenger is just folded in, but I'll remove it soon. Other plans for me in the future are rear wheel skirts and all wheel pizza pans, coroplast underbody cover, grille block, fuel injection conversion, possibly a 3.70 swap and port + polish (GF's dad is a CNC machinist woot) LLR tires, couple inches lower. Honestly an EJ22/18 (or EJ15!!) swap would probably be easier and more efficient, but I'm an EA lover. I'll mess with a Legacy or Impretzel when I have more money. As I've only gone through a couple tanks so far, I'm still experimenting with how RPM vs. speed effects my mileage. 55 should be better than 65, but then I need more throttle.... stupid carb! I drive 300 miles a week to work, so it shouldn't take me long to figure that one out. Quote Link to comment Share on other sites More sharing options...
Scoobywagon Posted February 3, 2010 Share Posted February 3, 2010 I'd start with an SPFI swap. Don't block the grill, though. EA82s are very particular about their cooling. Lowering it and giving it some side skirts would probably do wonders Quote Link to comment Share on other sites More sharing options...
derburger Posted February 3, 2010 Share Posted February 3, 2010 I see I'm not the only ecomodder forum user here Yes, XTs pwn wagons in the cda department, but epically fail when it comes to hauling Christmas trees. Quote Link to comment Share on other sites More sharing options...
vagen Posted February 4, 2010 Share Posted February 4, 2010 (edited) I could use the taller non-turbo 5th gear my RX feels like 5th is just 4th and a half. I've on more than one occasion thought I was in 3rd and tried for another gear. When I picked up my RX I drove it 210 miles to get home never hitting boost and managed a staggering 42mpg. I later backed that up with a 116 mile MPG rally through the mountains with 37mpg. these can be efficient cars but the RPM needs to be kept low to do that. if you can manage the swap a 3.7 ratio front and rear diff will help a lot.....just don't expect it to have any form of quickness to it. as far as aero mods My advice is look under the nose of the car. draw a straight line parallel to the ground from the nose back. If anything is below that either raise it up or lower the nose (airdam). you can add a bellypan to these cars but TBH the belly is pretty flat as is (just the bits that hang below it are a pain). These cars aren't awful Aero wise but they are a 30 year old design. I too am on ecomodder and Gas-savers as well Edited February 4, 2010 by vagen Quote Link to comment Share on other sites More sharing options...
Subaru_dude Posted February 4, 2010 Share Posted February 4, 2010 Driving my GL compared to my Outback, I would definitely say the GL cuts through the air better. It also gets about 4mpg better on the highway. I managed 41mpg in my EA82 sedan once, I wouldn't be suprised if you got that out of a 2wd spfi 5spd wagon. Quote Link to comment Share on other sites More sharing options...
SakoTGrimes Posted February 5, 2010 Author Share Posted February 5, 2010 LMAO! Be honest, did you go out and do that just to prove me wrong? Holy crap that was funny! Quote Link to comment Share on other sites More sharing options...
4WDFrenzy Posted February 5, 2010 Share Posted February 5, 2010 need to swap an xt front clip to the ea82 wago, and then make a huge long tail fin out the back rear like a teardrop shape cone off the back.cover the rear wheel wells with fenders from a Honda Insight put aluminum pizza pans on the front rims. Its easy as pie. low rolling resistant tires aired to 50psi gut the weight, and underbody shield, lowered of course. easy, dont forget new plugs, wires, air filter, fuel filters, and the best tuneup you can give it, and a good grade of Amoco Ultimate or Sunoco premium. Use full synthetics on oil, that reduces friction internally. maybe port and polished heads and a better cam, ditch all unneccessary electronics, they draw power from the alternator (no radio) Sounds ike you're ready to run on the salt flats with that setup! -Patrick Quote Link to comment Share on other sites More sharing options...
Crawlerdan Posted February 5, 2010 Share Posted February 5, 2010 i had a 94 loyal wagon, lifted 2 inches, 27 inch all terrains, 5 spd, non turbo, consistantly saw 42mpg in it, but i would get on teh highway and not pull off till it needed fuel, i had a 362 mile commute. the larger tires effectively acted like an overdrive on the hwy, reducing rpms at a given speed Quote Link to comment Share on other sites More sharing options...
4WDFrenzy Posted February 6, 2010 Share Posted February 6, 2010 Here is an interesting idea that I haven't seen mentioned. What about fabricating a rear bumper diffuser for the EA wagon? I mean, from all the things that I have read online(and yes, I know that you can't believe everything that you read) they help high speed (I know that this info isn't necessary when trying to obtain the most gas mileage) stability by channeling high speed airflow from underneath the car and smoothly transitioning it into the low pressure area behind the vehicle. IIRC, I also read somewhere that they can help improve gas mileage by increasing the aerodynamic efficiency of the vehicle. I mean, it may not be a huge increase, but I would venture to guess that any kind of improvement to fuel mileage would be another mark chalked in the win column for the good guys, right? It is just an idea. I have been entertaining this since I was overseas, but haven't had a chance to act on it seeing as my car is broken. - Patrick Quote Link to comment Share on other sites More sharing options...
SakoTGrimes Posted February 7, 2010 Author Share Posted February 7, 2010 IIRC, I also read somewhere that they can help improve gas mileage by increasing the aerodynamic efficiency of the vehicle. I mean, it may not be a huge increase, but I would venture to guess that any kind of improvement to fuel mileage would be another mark chalked in the win column for the good guys, right? In my opinion, airflow around the vehicle is the single most important factor in increasing fuel economy. Think about how hard it would be to stand up in a 65mph wind, now multiply your body mass by 5 and that's about the frontal area of your car. A lot of power goes to not just moving the car, but thousands of cubic feet of air per second. Even a high powered V8 car can get good mileage with tall gearing and a slippery shape (Corvette) Look at all the highest mpg cars ever built, they almost all have lower than average .cda's Quote Link to comment Share on other sites More sharing options...
Scoobywagon Posted February 7, 2010 Share Posted February 7, 2010 Look at all the highest mpg cars ever built, they almost all have lower than average .cda's Oddly, so does your wagon. Prius is .25 cD. Your wagon is about .27 cD. Aerodynamically, you're really not that far off. You might just go to a taller set of tires and see what you get. Its effectively a taller set of gears. I'd find a set of steel pugs (they're lighter than the alloys) and put on some tall, thin tires with a hard tread compound. I bet that something like a 195/70R14 would do well. Quote Link to comment Share on other sites More sharing options...
kingbobdole Posted February 7, 2010 Share Posted February 7, 2010 The XT/RX wheel caps were actually made to help with airflow around the wheels... Fender skirts would be cool too. Quote Link to comment Share on other sites More sharing options...
SakoTGrimes Posted February 8, 2010 Author Share Posted February 8, 2010 Your wagon is about .27 cD. Really!? It sure doesn't look very aerodynamic, but neither does the Mercedes C Class (cd in the low .20s) That would be super cool if my wagon really is that good. One day when I have it running properly I'd like to do the string tassel test to identify weak points and modify them. Quote Link to comment Share on other sites More sharing options...
robm Posted February 8, 2010 Share Posted February 8, 2010 Your method of finding the Cd is kind of suspect. The XT has a Cd of 0.29. The Nissan Cube has a Cd of 0.35. Somewhere in between would be a good bet. Roof racks are bad. The mudflaps are bad. Those little flipup thingies on the nosebra are bad. The exposed wipers are bad. The whole car is so bad, they probably don't make any difference! Smoothing the underside would probably be the easiest single thing you can do. But be careful you don't screw up the flow through the radiator. Quote Link to comment Share on other sites More sharing options...
bheinen74 Posted February 8, 2010 Share Posted February 8, 2010 nascar 100mph tape over the hood to fender joint gap, same for headlight gap to hood, and to side lights. smooth things up. Quote Link to comment Share on other sites More sharing options...
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