Seeking advice on scratch built car design/ideas

[Darrick147]

Ok, I've been pondering this subject for a few weeks and done some extensive research on it and I've decided that I want to build a car from scratch. I have quite a few questions and in need of some advice. I have the basic design in mind and I know for a fact that I want to run in some A-Mod Solo2 comps with it when it's done, but also would like to make it street-legal if possible. That should lay down some basic parameters for the goals I have for it. I'm having a few issues with decision making that will ultimately decide the potential of the car and I'm beating myself to death with these questions.

My thoughts/questions/wants mixed into one, somewhat easy to read list:
- Mid-engine, RWD (RMR)
- Space frame chassis (tube/square bars and size would probably depend on my engine choice/power output/suspension geometry, I would imagine)
- Four wheel independent suspension, double wishbone, pushrod dampers(inboard/outboard to be determined. not completely set as I have not input any suspension geometry into SolidWorks yet.) Also, I've been reading that a Miata rear subframe and powerplant could work well with my basic design ideas. Any comments/experience with those components?
- I'd like to use a 4 cyl. engine and wanting between 190-250hp, (very realistic for this sort of car, IMO) but not sure of what specific engine to use. Like I said above, a Miata engine could work, but I'd like something with a little more umph i guess. I'm an ex-DSM owner so, my first thought was a 4g63 head/4g64 block combo, but there's a lot of other viable (and much less technical) options out there. I've also considered a Honda {B16, B18} possibly w/ a small supercharger?, F/H22, K20, Toyota 4age, Nissan QR25, although it may end up with a little too much torque after a couple of mods, (I'm a current owner of a Nissan with a QR25 .) Nissan SR20de/T, Mazda L3-VDT, but I'm having a hard time deciding. (also an aluminum head and block would be awesome for weight saving, but there's some good iron block/aluminum head options that are great too. Any suggestions/advice/enlightenment on this would be greatly appreciated.
- Probably 15-17" rims w/ 6.5-8" width (will depend on which size works with the suspension geometry the best)
- Would like to do something like the big overhead air intake deal on the Ariel atom, but 2 small ones instead of one big one. One specifically for air intake and the other routed to the radiator. (stupid idea?, the way im imagining it, it'd be pretty sick)
- 2 rollover bars similar to whats required on FSAE cars, (for rollover safety reasons obviously) but 1 or 2 full roll bars that run completely over the cockpit, would look alright, I think, and would make the chassis more rigid (and safe also . )
- I'd like the seats to be directly in front of the engine and have them both as close to the center of the chassis as possible in order to have a good CG and moment of intertia.
- 4 wheel disk brakes (possibly wheel hubs/brake assemblies from an MR2? unless using the Miata rear subframe)
- Adjustable drivers seat (so that both of us building the car can drive it).
- If not using a Miata rear subframe, what would be an viable rear differential/subframe?
- Transmission suggestions? Looking to AutoX it and probably making it street legal in the future, so a 6 speed would be great, but 5 speed works just as good. (of course this would completely depend on what's available with which engine i go with, but an automatic is absolutely out of the question. I haven't even driven an automatic DD in 7+ years)
- I'm wanting a ride height that's optimal for AutoX, but is also legal to be on the street. adjustable coilovers/dampers budget permitting. (again, reference the Ariel Atom).
- Not looking to do a full body on it. I'd like to keep it as an open wheel, with a front body cover, side body pieces to direct air where it needs to go, and probably nothing covering the engine and it's components in the rear other than the intake cowls I was talking about and a sufficient but not overzealous spoiler. This is to be determined, depending on how the frame/chassis/rear subframe looks in solidworks/soidworks aero simulations.
- I heard from an engineer friend that a lot of people tune these cars to run E85, which sounds like an awesome idea, but is dependent on $$ confines towards the end of the build since it requires a few fuel system upgrades.

All in all, I think it's going to be a really fun project. Looking to spend 3-5 months in the design phase to limit the design errors and changes during the build process and to save some money for the build. Hoping for it to come out looking sort of like a cross between a big FSAE machine/Ariel Atom/Lotus 7. Once I decide on the suspension geometry/engine/frame specifics, I'll post a rough SolidWorks 3D mockup of those components at least and see what you guys think. May take a couple weeks since I have to purchase a new Solidworks student license since I didn't renew it after I left school last year.

All comments, advice, experience, insights, and criticism are absolutely appreciated.
Thanks so much in advance, I know that post was probably a beating.

-Darrick147

[Moppie]

Whats your budget?

If it's less than 100K then go and look at an existing Lotus 7 style kit, or just buy an Atom.

If you have the money and your really serious, then a Honda K20A makes an excellent power plant to build around.
There is already plenty of data on the net and existing systems for dropping them into mid engine configurations. They are already used in the Atom, and are a popular conversion for Elises.
And, they are an easy 200hp out of the box, with 240hp needing only minor modifications.

[Darrick147]

Thanks for the feedback. I plan to take my time on the build, most likely a 2yr project. My budget is *about* $12k spread out over the time it takes to build the car. I have a couple friends that work a junk yard about 10 miles from my home that can get me cheap/free junk car parts, so although $12k doesn't seem like a huge budget, I think that it'll do just fine.

Which cars came stock with a K20A?

[simmypam]

Interesting project. Of course, feel free to ignore my suggestions. I've thought about similar projects. I think the main idea is to keep things simple, simple, simple. A car engine and transmission is going to be heavy. When I was brainstorming engine ideas, I was thinking about a Valkyrie or Goldwing 1.5L flat six. I also believe that their transmission has a reverse gear, I can't remember. A 1.5 litre flat engined single seater--sounds similar to this: http://iedei.files.wordpress.com/201...mula_1_car.jpg

I'd also look to the LCC Rocket for inspiration and direction. It is considered to be one of the best drivers cars out there, and it's road legal.

http://www.lccrocket.com/