Building a car from scratch- how would YOU do it?

[johnpr]

personally i would go with a trike but go with an a-arm setup in the front, probably look similar to the aptera but i dont think i could bring myself to using an ICE. i would have to go electric with the pv film that can be formed into different ships to flow with the body design.

[NoCO2]

If you could figure out how to do a flexible PV shell then doing an electric car would be EXTREMELY feasible for almost all people. The main problem I find with EVs, for me anyway, is that I have no place to plug them in as I live in an apartment complex where I park in a parking lot...not very near my apartment, at least not within extension cord range. A PV shell would allow it to charge regardless and I think if you made the ENTIRE body out of PV cells, then it would probably charge up rather quickly, at least in PV output terms. Can anyone chime in about this? How efficient would an entire body PV cell be, like making every panel a cell? I would probably make mine a small 1.0L turbo diesel with the electric assist for < 35mph driving and have all the recharging being done by the PV cells so that no efficiency is removed from the wheels or motor.

[Joe_Bloe]

Originally Posted by ebacherville

My version would probably consist of a 125 -250 cc scooter drive line, for the ultimate in MPG's.. 250 cc scooters get great MPG and do freeway speeds.. even a 125 will do 60mph pretty effortlessly..

However a water cooled motor is preferred, use the radiator as cabin heat in the winter.. in the summer just vent to the outdoors.

That's exactly what I was daydreaming about in the shower this morning. Tadpole with a Honda Helix drivetrain (250cc, liquid cooled, CVT), modified with a megasquirt EFI and a 5KW electric motor paralleled to the input of the transmission. I bet it could do 100mpg easily.

[dcb]

Originally Posted by jamesqf

I would really dispute claims that a motorcycle (at least one that I'd ride on the highway - 500 cc at a minimum) is really fuel efficient.

That is like saying cars are not fuel efficient because hummers are not fuel efficient And 50mpg without trying is good! Less rubber on the road and smaller frontal area and a streamlined body (and a small engine) for our imaginary vehicle are a formula for mpg success.

[Tony Raine]

i like the "tadpole" ideas best. especially the VW front end, for cheap off-the-shelf replacement parts. small gas engine in the rear with chain drive single rear wheel (more labor-intensive, but easier to play with gearing). tube chassis with tabs to mount your fenders/hood/windshield/headlights of choice (miata, geo, civic, etc...) also for ease of replacement parts. under the hood is the "trunk". teardrop the back with removable panels to work on the motor/wheel. smooth belly. spartan interior. mesh seats, no dash panels, just a scanguage-type instrumentation for guages, small (adjustable) scoop under the car to channel (filtered) air into the cabin for summer driving, wear a jacket for winter.


for something a little different, what bout 2 wheels in the back, but very close together? like a traditional rwd solid axle, but narrowed to the point of only having enough room for the differential and a swingarm-type link suspension. maybe use this for extra weight-carrying capacity of a 4 seater in similar fashion of the above idea?

[NoCO2]

For anyone actually seriously considering doing this (and I'm one of them), I found a little gem that should be bookmarked by everyone interested.

http://www.access.gpo.gov/nara/cfr/w...cfr571_05.html

[MechEngVT]

The problem with the VW front end is that you will be limited to a vehicle that's approximately as wide as a VW. This would work great on side-by-side reverse trikes but increases your frontal area over a tandem.

Decreasing the frontal area is one of the easiest ways to improve aero, plus by lengthening the vehicle it will be easier to improve the Cd.

I would go reverse-trike tandem like the VW 1L concept and even knock off their general shape (I'm guessing trikes have fewer anti-regulatory advantages in Europe). That concept uses an 8.5hp/13.6 ft-lb 300cc diesel to get between 235 (quoted range of 404 mi on 6.5L fuel) and 317 (stated in the article) mpg according to the link. I wonder what could be done with a Honda iGX440 (438 cc, 12.7hp@3600, 22ft-lb@2500). It has electronic start/stop built in and has application-configurable electronic speed control. You could pair it with a CVT and it would be ideal for pulse-glide, plus it would be nearly off-the-shelf for a DIY trike project and even though you'd be lucky to get 50% the economy of the VW 1L, you're still talking 117-158 mpg. Based on the height/width of the 1L and the stated Cd I estimate the CdA at ~.16m^2, so if aero was the only drag the iGX should push you to 93 mph assuming 25% drivetrain loss, so add in rolling resistance or hedge drivetrain loss and you're still above highway speeds. I wouldn't want to accelerate uphill with two-200lb riders plus groceries, though.

Because of a tandem setup I would go with SLA suspension. Given the single rear wheel I wonder what geometry would be favorable and stable, but you'll either have to go negative-SLA to put the roll center below ground for an understeer gradient or get extreme with a x-over positive SLA and put your roll center above the vehicle's CG and it will actually lean into the turns

Since the car will be narrow and long with SLA front it would be ideal for a longitudinal torsion beam front suspension more in line with late-60s Chryslers (E-bodies, B-bodies).

[Doofus McFancypants]

The forum that linked me to you guys was one for Lotus 7 replicas built on a budget - They called Locost 7 as the goal is to keep price down. It is a "Kit car" without the KIT as most of this is fabricated.

locostusa.com is the forum.

The main idea for the car is biuld a frame - many plans out there that have been tested and modeled to test for torsional stregnth. Get a Donor car for essentials ( like a Mazda Miata) and you have the core for the car. "How to Build a cheap sports car" is the inspiration for these guys - Keith Tanner is on the forum as well.

Not that a 7 is the most aerodynamic out there but for a Non highway driver - this could be a super sipper.
there is one guy builfing his own 100 MPG out of a 3 cyl tractor engine.

Several have designed and build Midies ( mid engine cars) doing exactly what you are saying - take a FWD engine and install in as a RWD engine.

one guy even wrote a book on it. and another did a sweet job finishing it up ( see pic atthced - looks really smooth.


Anyway - thought i would highlight a great forum for DIY car building.
I have also dreamed about building one - three things are stoping me.
Time - Money - Space.

Steve

[Tango Charlie]

...and then there's this...
http://www.rqriley.com/tri-mag.html

[88CRX]

What I'd like as a feature in an ICE drive train, is the same mechanism in the back wheel of a bike, which allow the back wheel to spin freely, when you stop pedaling.

Then you don't have always go to neutral.