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

[TrikeKid]

I'd just put a carbon fiber roof on a Caterham 7 with a little aero work and some tuning. Not metro fuel economy, not a grocery getter with 2 people, but it would be DAMN fun.

[bgd73]

a 3 main boxer and artsy modern aero people for the body. This go for a modern 3 main boxer would actually get away from the screaming ricer killing us all, and to analogize a common boxer: a beetle with a fifth gear actually fully using the 3 main boxers legendary torque. So difficult. so bizarre and outlandish..this crazy phenomona called "106 years of boxer engine facts"..
or to humor the very terrorizing country that thinks transverse and inline fours are spectacular, one could go get the smartest futuristic auto they ever made: An ea82 subaru, and go from there. Many injections, carbs, gears and all the stuff one could ponder...My first accidental 60mpg highway trip 11 years ago and only reassured by an older relative of the beetle and its unbelievable economy has kept me in pursuit of the only rotting subes left. the auto industry is so grotesquely dumb. Don't make me a leader. they'll be starving execs

[elhigh]

I'd put a Prius on a crash diet, shave about 1500lbs out of it, hog out the entire engine and all those silly batteries and do it up with the opposed-twin out of a Citroen 2CV.

If the engine isn't up to the job, try it again, this time in a stripped-out Insight.

[ATaylorRacing]

I would use a dune buggy and put the drive train from a Metro XFi in the back....keep the wt under 1000 lbs with me on it would be easy and with less wt comes better FE.

[cfg83]

beatr911 -

Originally Posted by beatr911

These are really cool. Not good for carpooling though.
DIY motorcycle/formula car. SportCycle

This one is fun. I like the 1 + (unhappy) 1 configuration :



Probably have to draw straws to get to drive!

CarloSW2

[solarguy]

I am building a shop behind my house to build a super-ultra-hyper-miler. It will be a reverse trike, aka teardrop, 2F1R, slingshot, etc.

It will have a very small frontal area and a very good CD (duhh...). It will seat three people plus baggage, and seating will be in tandem, not side by side. So yeah, it will be quite long, about 16'. It will look a lot like an airplane fuselage, and the canopy will be either the most challenging part, and/or the most expensive part. It will have a small 3 cylinder diesel making approximately 25 hp max. I'm hoping for a 6 spd gearbox from a motorcycle with a final drive using a cog belt (much less noise and maint. than a chain and much more durable). The cog belt/pulley system will allow me to tweak the final drive ratio to maximize fuel economy. It will be rear drive. Single wheel rear wheel drive should also have lower friction losses. There's no good way to do front drive and keep the frontal area as small as I want.

It will very clean aerodynamically speaking. No rear views (cameras instead), no wipers, no grill for a radiator and very integrated lighting. The radiator will be a sheet of copper integrated into the belly pan with coolant pipes soldered to the inside surface. It will also have a simple valve arrangement to dump heat into the cabin for winter heat. No AC unless I break 200 mpg.

It will have 1.5" square tubing for the metal subframe. You mount all the mechanical goodies to the subframe, and 5 or 6 plywood formers to mount the foam/west epoxy/fiberglass composite body. Several of the major body panels will be entirely removable for access and maintenance.

For general character and appearance, think a cross between the Aptera and a T-38 Talon.

I am very conflicted about what to do for a front suspension. I don't want a bunch of struts and linkages hanging out in the airflow. The front track will be fairly wide for stability, say 55", but the wheels will be mounted out at the end of a pretty thin crossmember, which will itself have a cross section like a low drag wing. Nicely faired wheel pants that steer with the wheels.

I won't be able to start on it for 2-3 years, as I already have a lot on my plate. I will use that time to sort out the design details as much as I can in advance.

I'm leaning toward having a canopy made by this guy:

http://toddscanopies.com/prices.htm

For an engine, I am thinking about the naturally aspirated Isuzu 3 cyl diesel in the 23-27 hp range, like here:

Isuzu - The Leader Of Industrial Diesel Engines

My first order, back of the napkin estimates suggest 105-110 mpg cruising 70 on the highway. On the back roads, averaging 50 mph and being able to use some pulse/coast, this thing should return well over 150mpg.

It will use automotive low RR tires that come rated for 50psi or better.

Can't quite figure out what to do about a spare tire...

I estimate the grand total for materials at under $12,000.

Finest regards,

troy

[Bicycle Bob]

For a surface radiator, you might look at snowmobile parts. They are sized for an air flow containing powdered ice crystals, so you'd need several. You might also look at flattening out refrigerator freezer compartments. I presume the weight will be far under the usual for car tires - any leads on a lighter tire/wheel combo?

You are right to be concerned about the front suspension area - it can be responsible for tremendous amounts of drag. I think you will find that double A-arms with a tension member to the spring will give the lowest frontal area, but interference is still a problem. You could save some detailing on the streamlining by using a low-pivot swing axle. Given that the vehicle will understeer anyway, and the tires should be narrow, you might even cross the axles, as in the Ford pickup "twin I-beam" arrangement. You can use a single transverse leaf spring to provide both suspension and anti-roll, and because it is a spring, it does not suffer structurally by being slender enough to fit within the streamlined axles taking the moment loads.
A similar spring can be used as an upper or lower pair of A-arms, but you still need a third member for the shocks. In designing integrated spring/arms, it helps to keep the flexing area fairly close to where you'd otherwise have a pivot. John Cooper neglected that point when he used Fiat bits on his first Formula 3 cars, and got oscillations under hard cornering.

[solarguy]

Dear Bob,

The three tire choices I have considered so far are:

OEM tires for my VW jetta. They are low RR and high pressure, not too tall or too short, readily available, not stupid expensive, and since they will be grossly underloaded, durability should be quite good.

VW Bug tires, some of the old (air cooled) Bug tires were pretty narrow, but probably not available with a higher pressure sidewall rating

Geo Metro tires, still hunting around to see if there are special "econo" Low RR tires for the metro.

For rims, I'll just get cheap alloy wheels and fab flush covers to reduce drag/turbulence.

For the radiator, I will build that by hand from sheet copper and copper tubing to integrate that seamlessly into the pan of the car. It solders easily, it forms easily, great heat transfer, etc.

I am debating about a composite front axle that does it all. I am not fussy about ride. Safety is a concern of course.


Finest regards,

troy

[bgd73]

solarguy has quite a thought going...

got me thinking of trike and ecomod..

if to not have the 180 fire of a four, and need to chase the miss...aerodynamics a must, lightweight.... A boxer2 cylinder benz style, and backwards trike or frontwards. As there is 3 wheels, i would cradle the engine with a wide part, so a forward trike may be better idea (axle back)...for stability and balance, resonance dispersing, etc.After driving a 2cylinder inline diesel tractor, the boxer would be even better...
100s mpg a big maybe....heavy flywheel blah blah blah etc etc etc

[Bicycle Bob]

I've been hunting tires to fit a Metro, and like the OEM tires from the early Honda Insight. The Citroen 2CV has some tall, skinny tires, too, and was engineered around them as the 1st radials.

As an ex-silversmith, I'd love to be beating out a nice copper bottom for a car, but for the weight, aluminum gives even more heat transfer, and you can solder it easily with zinc based rod.