open planning new car - Fuel Economy, Hypermiling, EcoModding News and Forum

cosmick · 03-06-2015, 01:01 PM

So as I'm past halfway on each of the 2 projects I'm currently working on, and can't work on at night right now, I've been planning a single-seater or inline-2-seater, custom fabricated frame, mid-rear engine, quasi-open-wheel (4-wheel) based on salvage yard used drivetrain and other major components.
Since it's generating some interest in another thread, I thought I'd open it up for everyone here in its own thread.
I know, this thread needs visuals.
Excerpting from that thread; "problem; side by side seating, rather than inline. That triples the total drag all by itself. Now I really want to get going on my own single seater or inline 2-seater, with either a 4G63T Mitsubishi engine or a turbo propane 22R Toyota engine in front of a V6 Passat transaxle."
" I've been trying designs in SketchUp Make, it is free downloadable 3d modeling. The Locost forum has great info for what metal is adequate, likewise plans for DIY CJ5 Jeep frames. I've done adapter plates before, getting either engine to that transaxle is doable. But enough about mine.
My reference to triple drag is not an exact scientific ratio, but is really obvious if you compare even something like the '83 RX-7 I'm building against something more like this: http://img546.imageshack.us/img546/3451/1326657812.jpg"
"I'm thinking most of my side-impact protection will come from nimble crash-avoidance, and secondarily from the overkill frame design I'm leaning toward, which has 2" x 2" mild steel square tubing of 1/4-thick wall thickness, along the occupant shoulders, on past the fuel cell, which would be between the occupants and the engine. The overkill steel would also go around the occupant compartment in other ways / areas, especially in front of the feet and something tubular curved overhead to meet the plexi canopy, if I can find a plexi canopy. Anyway, gasoline or propane will determine the firewall between fuel and human. I considered fuel in the lower frame, but then decided that's better for coolant hoses, brake lines, and possibly p/s if it proves necessary. These might all be braided stainless.
Still working on the fore-aft relationship between the driver's feet, the front suspension, and the radiator.
The bodywork is likely to be fiberglass formed over a hand-shaped wooden buck shaped by myself.
I need 60+ MPG HWY, I need it to spike at least 75 MPG at least twice, and it needs to be fun to drive anywhere, anytime, for under $10,000."
"Aircraft canopy construction
led me to:
Todds Canopies - Home
Their iceboat canopy is about what I was thinking if single-seat.
In fact, the whole back half of that looks good to me."

cosmick · 03-06-2015, 01:04 PM

Also, not the entire frame will be such overkill steel, only the part around the occupant(s), and possibly some of the structure for bumpers required under state motor vehicle inspection laws.
I'll try to post sketches tomorrow.

spacemanspif · 03-06-2015, 04:49 PM

Care to explain why you have chosen to limit engine choices to 1 of those 2 listed above? If you are making it all from scratch and plan to use as little steel and as much fiberglass, you could probably make a lean-burn 1.5 Honda fit and still be fun to drive. Or even a mid-sized motorcycle engine 750-900cc could work. It doesn't have to be stupid fast to be fun, especially if you plan on doing more turning than going straight when flipping the "fun switch".

ksa8907 · 03-06-2015, 09:29 PM

How much would this thing weigh? Anything less than 15lbs per hp is fun, imo. Closer to 12:1 gets crazy fun. More than that and you'll just get yourself in trouble.

At 1500 lbs you only need 100hp to be fun. A honda 1.7 liter puts out around 125hp iirc, that allows for 1800 lbs.

Im guessing this thing is going to be around 1000 lbs. A modern 4cyl would make it insanely fast.

sgtlethargic · 03-07-2015, 04:41 AM

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cosmick · 03-07-2015, 10:37 AM

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cosmick · 03-07-2015, 10:54 AM

Honda: While I must admit the VTEC feature is as reliable as the sun itself, and their newer heads really don't need much porting, my own past includes UAW training, ASE pre-certs, plenty of automotive engine machining experience, including building, testing, and living with what I've machined and built to my own specs.
Honda is the one brand I shun above all others, least worthy of respect. Yes, I've driven several, none of them "lemons".
I've been into cars since I was a kid, it's my only hobby, and it is my obsession. May even be a major contributing factor to why I'm nearly 39 and never married. Plus I am a tested and proven genius, with an IQ over 140.
Granted, some designs just get MPG better than others, but I will not waste a single second putting economy over fun. And there's nothing fun about any engine that isn't cheap to improve the output of, and cheap to get. Much easier to get the MPG up, even with an engine that isn't among the best of it's type.
Huge power is fun, but along he way I've discovered for myself how lower power can also bring smiles, which is why I'm willing to consider the 'yota. It's the cheapest way to run adequate power on cheap fuel, and it is reliable. Parts can be had anywhere, anytime. It's the 350 Chevy of propane 4s. The 4G63T is common, has huge aftermarket support for more power, is a good design, and can make far more power on pump gas than such an application can realistically use.
I understand a max-effort GM Ecotec 4 can make 1200 HP, but I'm neither wealthy, by choice, nor crazy. In my youth I chased the dollar, successfully, and now I'm much happier.
Weight: I have no clue, nor do I much care. I'm not planning on narrow tires for daily fun, only for long trips and MPG tests. The rest of the time I'm thinking 315-width DOT-approved drag radials on the rear, and 315-width DOT autocross tires on the front.
Those are affordable, as are the 17" x 11" wheels.
The rear suspension is likely to be based on an '88 Pontiac Fiero, while the front suspension is likely to be based on the Ford Mustang 2 IFS that all the "street rod" community has so embraced.
Lastly for right now, I didn't have the opportunity to work on any visuals, sorry.

cosmick · 03-07-2015, 11:05 AM

Update: I e-mailed Todd's Canopies for a quote, and I'm happy with his response: $ 425. He asked if I really want it that narrow, but I'm not sure if it is 15" or 20" as the width. Anyway, here's the reply I sent:
"Hello, Mr. Silver,
I was hoping the cost to be closer to the $500 price range than $5000, so I am now including your canopy in my plans. I really wondered if 20" was the width and 15" the height, or vice versa.
I'm thinking I'll need to get a canopy before finalizing the frame / chassis design, let alone any bodywork.
The single-seater idea is the minimum possible drag on the minimum possible frontal area, with a very reclined driving posture. No worries about claustrophobia, only clearing a safety helmet for an autocross. If I do inline 2-seater, then I may go for an untrimmed 76" with seating slightly more upright."