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rykoala 06-23-2008 06:52 PM

Building a car from scratch- how would YOU do it?
 
So lets say you were going to build a car from scratch and design it from the get-go to get the best mileage possible. The only restriction that I would put on it is that it has to be a full ICE drivetrain- no hybrids, no electrics. Two occupants (driver/passenger) and enough cargo space to have room for a weeks worth of groceries for 2 people.

So, how would you do it?

I personally would build a rear wheel drive with a fwd engine/transaxle in the rear, with the occupants side by side in front of it, and low to the ground, and very low profile. You'd have to step down into it. It would be no taller than required for reasonable comfort and enough height to accommodate the engine and radiator. It would also be just wide enough to handle the tires, with the rears enclosed in wheel skirts, and the fronts fendered but open like on most cars. The engine would be a 3 or 4cyl low displacement engine (1.0l would be more than enough) and the transmission a manual. Tires would be the narrowest I could find, and the body would be fiberglass.

But, I know little about car design. How would you do it?

(bored)

cfg83 06-23-2008 07:23 PM

rykoala -

I'd just build this :

Perry Ds 550 Spyder
http://www.kitcarmag.com/featuredveh...ica/index.html
http://images.kitcarmag.com/featured...r_replica+.jpg

I like it because it uses a STOCK VW chassis. The only problem from my POV is cleaning up it's emissions. I am sure you could find a replacement engine if you went on a quest and/or deactivated two of it's cylinders. Hrrmmmmm, maybe an OBDII compliannt Porsche Boxer engine with cylinder deactivation?!?!?!?!?

Put your groceries here :

http://www.kitcarmag.com/featuredveh.../photo_06.html
http://images.kitcarmag.com/featured...r_replica+.jpg
Quote:

The package tray behind the seats and just forward of the engine bay offers plenty of room for a long weekend's worth of luggage.
The Perry Ds, Inc. 550 Spyder

Here's the main website :

www.perryspyder.com

CarloSW2

whokilledthejams 06-23-2008 07:57 PM

Old VW front beam (for simplicity), and the rear half of a motorcycle-- a reverse trike. Small, seats two, handles like it's on rails, and still reasonably efficient, without the terror of an actual motorcycle. A teardrop-shaped body for minimum drag would be relatively easy, without being overly-long.

Johnny Mullet 06-23-2008 08:57 PM

Didn't Homer Simpson do this and fail? :)

1GCRXHF 06-23-2008 09:28 PM

Go with a small diesel motor, maybe an old VW. Then gear it way long, I would take super low revving diesel over a motorcycle type setup anyday, especially if I'm building it from scratch anyway.

MetroMPG 06-23-2008 10:05 PM

I think I'd go with a tandem layout (either 4 wheel or 3), like the VW 1L, or the Jet car 2.5.

http://www.metrompg.com/posts/photos/jetcar.jpg

ttoyoda 06-23-2008 10:24 PM

rykoala
You are describing this:
http://www.arielatom.com/
With a low power engine and more bodywork.

whokilledthejams 06-23-2008 10:57 PM

Quote:

Originally Posted by Johnny Mullet (Post 37617)
Didn't Homer Simpson do this and fail? :)

Spectacularly, if I recall.

Quote:

Originally Posted by ttoyoda (Post 37660)
rykoala
You are describing this:
http://www.arielatom.com/
With a low power engine and more bodywork.

You know, I'd bet an Atom is already halfway efficient, considering it performs on par with a lot of supercars. Taller gearing and a less aggressively-tuned engine (it comes with a Chevy in the US, and a Honda in Europe, I believe).

See also: Caterham Se7en:
http://www.uscaterham.com/home.html

whokilledthejams 06-23-2008 10:59 PM

Quote:

Originally Posted by Frank Lee (Post 37678)
I'd go trike for ease of passing a license inspection. And other reasons.

That's my reasoning, too. A reverse trike is even better, for handling and stability. Hence, my junkyard version of the VW GX3 and Peugeot 20CUP.

dcb 06-23-2008 11:12 PM

Quote:

Originally Posted by whokilledthejams (Post 37606)
without the terror of an actual motorcycle

I am having a difficult time with this statement. Most folks who ride motorcycles enjoy them immensely, and enjoy good performance/economy and handling to boot. Add a little trailer and carry all the groceries you want.

You shouldn't rule out the obvious winners due to preconceptions :)

Maybe one of these diesel jobs :

http://graphics8.nytimes.com/images/...es/600-klr.jpg


or wrap a 600-klt like this:

http://www.craigvetter.com/images/47...r-w-vetter.jpg

ebacherville 06-23-2008 11:20 PM

id do a tadpole (reverse) trike, havds down the most stable and easiest to build..

I have actually been debating doing this for a long time .. the addition of a diesel engine could really make it shine.. however its going to take some fab work,

The motorcycle with a front passanger are is farly simple to construct, easy to get road worthy as its considered a motorcycle.. hardly any regulations.. and the skape is a natural for a ideal tear drop shaped craft...

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.

dremd 06-23-2008 11:46 PM

Pure electric 550 Spyder.

cfg83 06-24-2008 12:04 AM

whokilledthejams -

Quote:

Originally Posted by whokilledthejams (Post 37679)
...

You know, I'd bet an Atom is already halfway efficient, considering it performs on par with a lot of supercars. Taller gearing and a less aggressively-tuned engine (it comes with a Chevy in the US, and a Honda in Europe, I believe).

See also: Caterham Se7en:
http://www.uscaterham.com/home.html

The Atom weighs 1400 lbs with a 245 HP Honda K20 engine. It looks like the K20 weighs in at around 350 lbs.

A 2nd Gen Honda CRX HX engine, D15B6, weighs in at .... can't find it, :( . Let's assume 50 lbs less than the K20 for the purpose of comparison. The HF is 62 HP. It weighs 1967 lbs. From this we can compare power/weight ratios :

2nd Gen CRX HF : 1967 lbs / 62 HP = 31.72 lbs / HP
Atom + HF engine : (1400 - 50) / 62 = 21.77 lbs / HP

The Atom+HF is better than a CRX DX :

2nd Gen CRX DX : 2102 lbs / 89 HP = 23.61 lbs / HP

This implies (to me) That an Atom+HF would get the MPG of an HF with the zoom of a DX. Coolio, :D .

CarloSW2

rykoala 06-24-2008 12:05 AM

I love the trike ideas! The VW front with a low power pusher motor in the back makes really good sense. I really want to build something for a car. I just go done building my own recumbent bicycle and have 3 more to build (the whole family wants one!) but I have wanted to build my own car from scratch ever since I was a kid. Maybe next year I'll start it, and will be able to start gathering parts over the winter.

So any other ideas?

cfg83 06-24-2008 12:08 AM

dremd -

Quote:

Originally Posted by dremd (Post 37694)
Pure electric 550 Spyder.

Ask and you shall receive :

Electric 550 Spyder
http://www.ohler.com/ev/spyder/
http://www.ohler.com/ev/spyder/2001....rFrontHood.jpg
Quote:

Once running the track time sheet will be added to the page. I'm shooting for 0 to 60 mph in under 5 seconds. The car weighs 2600 pounds and the weight ratio, front to rear is 44/56. The motor develops over 300 horsepower.
CarloSW2

Duffman 06-24-2008 12:16 AM

Quote:

Originally Posted by Frank Lee (Post 37678)
I'd go trike for ease of passing a license inspection. And other reasons.

I know every state/province is different, but as long as you start with a roadworthy VIN, I think you could cut and paste a firewall/dash onto any project you wanted.

rykoala 06-24-2008 12:19 AM

Quote:

Originally Posted by dremd (Post 37694)
Pure electric 550 Spyder.

Quote:

Originally Posted by rykoala
The only restriction that I would put on it is that it has to be a full ICE drivetrain- no hybrids, no electrics.

;)

Duffman 06-24-2008 12:32 AM

I think it would be highly possible to build a 40+mpg 32 Ford Coupe using reproduction Fibreglass bodies. Small nose, an engine bay that you could do anything you wanted, and the cool factor is a 10 out 10.

http://farm2.static.flickr.com/1243/...d73a8e.jpg?v=0
http://www.members.streetrodcentral..../roberts32.jpg

rykoala 06-24-2008 12:37 AM

While searching for 2 cylinder VW engines, I ran across this. I'm sure y'all have seen it, but I think its very cool. Too technologically complex IMHO, but 317mpg is nothing to laugh at!
http://www.canadiandriver.com/articles/gw/vw1litre.htm

Vince-HX 06-24-2008 02:39 AM

linkpin vw front beam for low maintenance and ninja 250 engine and swingarm.

Kawasaki just released the "updated" version of the Ninja 250 this year so older models go for way cheap. The engine is very simple and makes 36hp and 17 lbs plus it has a 14,000 redline:thumbup:

I have a 2005 Ninja 250 that I ride the crap out of and the worst mileage I ever got was 45 mpg, and i'm talking about practically redlining it in every gear, lol. SuperSuperfun bike though, and i'm a 200 lbs guy


In a chassis with better aerodynamics (motorcycles are horrible) I would think 100+ mpg is possible with a few mods like a sprag clutch. That would allow you to Pulse and Glide super easy because the trike would freewheel anytime you got off the throttle.

This is exactly what I plan to start building in the next month. I was able to score a complete low mile 1995 250 for $200 and I have a few front beams to choose from in my backyard. Should take only about a month and less then a total of $1000 to complete.

Sure a scooter engine would work but 14,000 rpms of 250cc fury sound AMAZING

nwbabybronco 06-24-2008 06:21 AM

I'd pick a catchy title, like "100mpg at 100 mph" or "33mpg with 33 in tires" (two goals of mine). Then I'd get a welder and go to the VW junk yard.

I, too, like tadpoles. I'm trying to figure out how to make something that is legally a Samurai, but mechanically a sidexside UTV - or something like that.

whokilledthejams 06-24-2008 07:12 AM

Quote:

Originally Posted by dcb (Post 37686)
I am having a difficult time with this statement. Most folks who ride motorcycles enjoy them immensely, and enjoy good performance/economy and handling to boot. Add a little trailer and carry all the groceries you want.

You shouldn't rule out the obvious winners due to preconceptions :)

I have never been on a motorcycle, but I enjoy at least some semblance of a body and more than two wheels. That's just me.

dcb 06-24-2008 07:41 AM

It's the cage that induces rage :) You will be hard pressed to see a biker not paying attention on the road.

IndyIan 06-24-2008 08:12 AM

Poor man's Aptera
 
I was looking at the pictures of the Aptera and it stuck me, its basically a small airplane fuselage. So how about an old cessna cockpit and fuselage minus the wings and tail, with a 400 or 500 cc liquid cooled twin cylinder motorbike drivetrain at the back. Even a single cylinder would work but it would probably rattle your brains out after a while, I wouldn't go any smaller due to the lack of torque and high rpms can't be all that good for fuel efficiency even though they are fun...
Front suspension and steering should come from something light and narrow, a suzuki swift for example. Grafting the front end parts would be a bit of a challenge but it would be light, aerodynamic, and well sealed up to the weather. I guess some cessnas even seat 4 with luggage but I imagine the rear bike suspension wouldn't handle huge loads for too long.
Ian

NoCO2 06-24-2008 09:46 AM

I would build a trike like was mentioned earlier, two up front and one in the rear with a diesel engine BEHIND the driver, leaving all the room ahead of it for passengers and luggage. The engine would be a three cylinder VW turbo diesel, similar to what is in the TDI new beetle, etc. The interior cockpit would hold three people, one up front to drive and then two staggered back behind him/her on either side. up front would be a storage boot, much like the 550 spyder has. The shell would be made of fiberglass and aluminum re-enforcement. Manual transmission with a 7 speed gearbox, all of them geared a little high so cruising speed can be maintained in a very low RPM range.

elhigh 06-24-2008 10:12 AM

Tadpole configuration with a Caterpillar diesel in the back driving the rear wheel. Before you cough and sputter, Cat makes some very small 2- and 3-cylinder diesels that are perfect for this. Loremo, eat your heart out.

Side-by-side seating for two. I know tandem is slipperier, but I want to be able to talk to my passenger. VW front beams since it's proven and easy to get.

I've drawn so many different iterations of this exact idea it's not even funny. Now all I need is a few thousand buck$ to make it happen.

Lazarus 06-24-2008 10:20 AM

This goes alone with what folks are saying but it's a pretty good read.

stormbird 06-24-2008 10:55 AM

I fancy this :-
http://www.thetrivette.com/PICTURES1.HTML

2cv floor pan reversed , has 602 cc and does 45-55 mpg in a 2cv so should be good for 55-70mpg ? in this without trying to hard ?

regards Paul

jamesqf 06-24-2008 07:36 PM

Quote:

Originally Posted by dcb (Post 37686)
Most folks who ride motorcycles enjoy them immensely, and enjoy good performance/economy and handling to boot.

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. I've owned a number in my life - from old 350 Hondas to 850 Suzukis - and never managed to get much over 50 mpg. Aerodynamics, I think (or rather the lack thereof), plus engines configured for power/acceleration rather than economy. Handling is OK until you find yourself in the midst of an unexpected snowstorm (not an infrequent thing hereabouts). And I've never figured out a good way to take the dog along...

But if I were going to build a car, I'd find a wrecked Honda Insight and turn it into a 3 wheeler, with a body as close to the Aptera as the engine would allow. If you insist on not having a hybrid, you could dump the batteries and add an alternator :-)

rykoala 06-24-2008 07:56 PM

I love all this creative thinking.

So, the general consensus seems to be trikes. I can surely see why! They make good sense. There is also a strong gravitation toward a VW front end with a motorcycle rear.

Does anyone have any drawings of what they have come up with?

johnpr 06-24-2008 10:17 PM

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 06-25-2008 08:42 AM

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 06-25-2008 09:07 AM

My (imaginary) x-prize entry
 
Quote:

Originally Posted by ebacherville (Post 37687)
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 06-25-2008 10:29 AM

Quote:

Originally Posted by jamesqf (Post 37990)
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 06-25-2008 11:34 AM

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 06-25-2008 11:50 AM

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 06-25-2008 12:29 PM

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 :thumbup:

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 06-25-2008 12:55 PM

Great resource for home built cars
 
2 Attachment(s)
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 06-25-2008 01:06 PM

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

88CRX 06-25-2008 01:54 PM

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.


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