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| Proximacentauri's Mid-Engine Exocar http://locostusa.com/forums/viewtopic.php?f=36&t=3030 |
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| Author: | proximacentuari [ December 21, 2007, 12:46 am ] |
| Post subject: | Proximacentauri's Mid-Engine Exocar |
This is my build log - I'm building an Atom-style semi-locost mid engined car. I started at the beginning of the summer of 2007. So far: June-August 2007: Summer job to raise money Reverse engineering of pictures Learning of Cad Building of Cad Model Learning to Weld Reading books on suspension etc. August-September 2007: working with a friend doing FEA analysis on the frame to determine the results of a crash. September 2007: front and rear box built, beginning to learn how to effectively tack weld and use a tubing notcher October: College Applications November: Four main tubes bent Frame progress December: frame nearing completion. Hopefully I'll be done by Christmas. The Project Plan: January-Feb: Acquire and disassemble donor car Feb-March: a-arms/suspension and mount motor March: get motor working April: Begin composites and get pedals/brakes/radiator/gas tank/steering working May: troubleshoot June: troubleshoot/finish composites Things I've Decided: Frame: mostly ERW tubing, roll bar components DOM A-Arms: 1" DOM tubing Shocks: Koni drag shocks Donor Car: 2002-2004 Civic SI (160 HP, cable shift, rear-facing exhaust) Knuckles: stock with fabricated steering arm Brakes: stock Pedals: Tilton pedals/ MCs/ with balance bar Accelerator: stock Clutch: stock Seats: F1Spec type 2 seats - great for the price, two fiberglass seats, mounts/sliders for 400$ Steering Wheel: Momo Race Steering Rack: Sweet or Woodward manual rack (whichever comes up on ebay) Gas Tank: 10X30 10 gallon tank from Dansperformance parts, with sender/sump/fuel return/larger holes/remote fill Exhaust: custom with stock muffler Many thanks to JonW and the rest of LocostUSA for ideas! For those interested in what I've done so far, check out my flickr acct at http://www.flickr.com/photos/25435483@N00/ |
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| Author: | mr.peabody.d [ December 21, 2007, 4:41 am ] |
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Very nice! I was surprised to see a computer side crash taken into account. I like it. I am impressed by your build so far I am sure a lot of guys would love to see & play with your computer model ... any chance of releasing the plans? Really nice build so far I welcome you to the community and Kudos on your build so far. I look forward to learning more about it. |
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| Author: | KB58 [ December 21, 2007, 10:07 am ] |
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I don't believe drag shocks will be appropriate, unless that's all you're doing. They're valved to extend quickly to aid load transfer, which isn't what you want for a street or roadracing car. Yeah they're cheaper, but not the right solution, sorry. I cover that in my book, and covers virtually everything you're doing. BTW, what diameter curved tubing is that, they looks huge! |
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| Author: | e30sho [ December 21, 2007, 11:00 am ] |
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Looks great. Tube fit-up is very nice. Keep up the good work and thanks for sharing. FWIW I think the best deal going for shocks is custom valued Bilsteins. Check out my build log for more on my thoughts on that or check out http://www.shock-shop.com/ . Chris knows this stuff inside and out and has been very responsive and helpful via email. Peter PS: Kurt, according to his build photo comments at http://www.flickr.com/photos/25435483@N00/2125647775/ its 2.5” tube. |
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| Author: | proximacentuari [ December 21, 2007, 2:26 pm ] |
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Thanks for the advice with the shocks guys. I'll probably end up buying some shocks off ebay. I didn't know that drag shocks were a different valving...I just thought it was the manufacturer's way of saying that they weren't for any specific car. Yeah, the tubing is 2.5" .065. The smaller stuff is 2" .083. The roll points, front and rear, and the back's support, is 2.5" .120 wall DOM. Heavy, but i'm not taking any chances. Plus, the extra metal in the back means that the engine won't get to ride shotgun in a front-end collision. About the model - pm me. I'd be happy to share. |
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| Author: | KB58 [ December 21, 2007, 4:37 pm ] |
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You can't just use any shocks. They have to be matched to the spring rate. Well, okay, you Can use random shocks, but the valving won't be appropriate for the springs, so it'll be either over or under damped. |
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| Author: | tomtom [ December 21, 2007, 11:10 pm ] |
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Looks good. Out of curiosity, where do you have applications in at for college? |
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| Author: | eVox [ December 27, 2007, 8:36 am ] |
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looks great so far. Glad to see a young guy that is doing the round-bent tubing approach to frame building. Im also curious about the college search. Georgia tech wouldnt happen to be on that list, would it? |
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| Author: | Sharp21 [ December 27, 2007, 11:04 pm ] |
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That looks great! Where are you planning to mount the fuel cell? S. |
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| Author: | proximacentuari [ January 3, 2008, 2:54 pm ] |
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The fuel cell will go in the same place it is on the At-om, directly underneath the rear roll point, behind the passengers. I considered the front, but I don't have enough money to buy a full-on crash-safe fuel tank. A couple fuel questions: If I use a Honda K20a3 engine, what will I need for the fuel tank. I'm planning on using an aluminum tank (10gal) with a sump, sender, and fuel return. Do I need anything more? What size fittings will allow full fuel flow to the engine? Also: I will be using the stock knuckles from the RSX/Civic SI. The front knuckles are macpherson struts. Therefore, the force of holding the car up will be placed on the bottom ball joint. Since there is little up-down load on the ball joint in the RSX, do you guys think that the stock bottom joint can handle the pushrod as well as the normal a-arm? Picture of the knuckle: http://cgi.ebay.com/ebaymotors/01-04-honda-civic-OEM-front-R-brake-knuckle-spindle-si_W0QQitemZ200126868766 |
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| Author: | KB58 [ January 3, 2008, 8:14 pm ] |
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You need to ask such questions on honda-tech.com and K20.org. |
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| Author: | proximacentuari [ January 19, 2008, 1:00 am ] |
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Update: Things completed since last: Many more frame parts in. All frame pieces officially required are tack welded. Welding is slow, but i'm learning quickly. Tomorrow, I'll buy some square tubing to form an additional step in the tub. As it is now, it's impossible to get in and out of the car without stepping on the seat, which I don't want. By placing a bar about 6 inches in front of the seats, it gives the driver/passenger a place to step when getting in and out of the car. In related news, I cut and fit one piece, the first time. Too bad that I finish the frame just when I start to get good at fitting tube. Also, solidworks is in the mail, alibre just doesn't cut it for modeling suspension stuff. The next step is finding a donor car. I need a crashed RSX/CIVIC SI...preferable a rollover. Updated hi-res pictures are on my flickr account, see earlier post. I asked several questions about suspension and fuel over at k20aforums, the url is http://www.k20a.org/forum/showthread.php?t=38559 |
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| Author: | Locost 5.0 [ January 19, 2008, 1:56 pm ] |
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You should be an expert at fitting tubes after that frame! Can't wait to see the suspension. What is the wheelbase and track? That is a great looking frame. Rod |
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| Author: | proximacentuari [ January 20, 2008, 1:52 am ] |
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To be honest, the wheelbase and track are whatever they come out to be. I've built everything in the frame to be tolerate to around 4-5 inches in every direction, so the wheelbase and track will finalize themselves once I build the suspension simulation model. |
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| Author: | Miatav8,MstrASE,A&P,F [ January 20, 2008, 9:54 am ] |
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Nice looking frame. Is that exhaust tubing? What is the wall thickness and tube diameters? Regarding the lower joint, your dropping about 1000-1500 lbs compared to the civic but I would still be concerned. The At-om uses a custom upright but I haven't seen any good photos of it to show the lower joint attachment. It would not be an issue with a rocker upper arm or a pull rod on the upper arm. If your determined to duplicate the At-om suspension, then either make uprights with the correct joints or frequently inspect the stock joints for looseness. The fuel fittings should be as large as the original fittings for the civic. Trap door baffles would be a good idea too. |
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