Custom Car Brainstorming
 

Since I'm pretty much done modifying the aerofocus, I'm ready to move on to the next thing. Something I've always wanted to do is make my own car. I spent a while deciding on front wheel drive vs rear wheel drive, mid engine vs front engine, and 4 wheel vs 3 wheel.

My current plants are:
to build a mid-engine RWD drive 4 wheeled car with a narrower rear wheel track. I plan on using a geo metro 3 cylinder mated to a 5 speed. The reason for the mid engine is to be able to build an optimal front end and rear wheel drive because if the engine is back there, might as wheel put the power back there.

The purpose of the build is to create the most fuel efficient car I can and learn a lot about building a car! My dad was a mechanic for most of his life, so I'm confident we can handle everything. This will be done on a relatively inexpensive budget(aka reusing things) but it won't be cheap or ghetto either.

I am still up for input on many things, so here is a list of things to stimulate some brainstorming

3 wheel vs 4 wheel?
gas vs diesel?
turbo vs non-turbo?
OBD 2(post 96) vs not OBD 1 or whatever(pre 96)
It looks like I'll need airbags here in Ohio, although I haven't confirmed that. so that adds a slight challange. I may use the passenger compartment(A-pillar to B pillar) from the donor metro so I can have airbags, but I'll be gutting everything else out.

Ideas I've thought about but thrown out:
3 wheeled powered by a motorcycle engine. I'm not too keen on the idea of using a motorcycle engine/transmission to move something 2-3 times the weight it was designed for and I like the idea of having 4 wheels on the ground during winter.

4 wheeled with even track front and back
I've decided on the narrower rear track because it allows me to taper the whole car in earlier which reduces drag and will help my highway MPG.

My current "blueprints":
http://i1271.photobucket.com/albums/...us/design1.gif

Take note of my rear exhausted radiator. the air inlet slots on the side of the car will be able to open and close when needed and the vacuum behind the car should help pull air through the system. Let me know if this is a bad idea, but I think it's a pretty good one.

Here is a link to a website showing what I'll basically be doing: Dad's Dune Buggy. Mine will have a body around the frame and be road legal. It looks like he re-used the front suspension in the rear. If so, that seems like a real good idea to save time and money and be sure of the safety aspect.

I plan on going all out with the drivetrain modifications and the aerodynamics so hopefully I can reach 100 mpg while cruising at 60 mph. That may be a lofty goal, but I always figure it's good to aim really high :thumbup:

Again, let me know what you guys think about the build. I'm hoping to start construction this summer, but finances will be the main constraint.

By the way, it would be cool if you guys could make some of those fancy renderings that you always make so we can get a better visual than my sketches. :D

have you seen this thread:
http://ecomodder.com/forum/showthrea...tml#post336418

This looks like a cool idea. As for the radiator inlets, a NACA duct would be the ideal inlet without introducing drag. However if you already have the sides tapered inwards following the "template", I'm not sure how well the air will be able to curve in beyond that into the duct. It may be a non-issue all together, but something to consider.

I really like the idea of using a FWD engine/ trans layout in the rear, that seems like an awesome way to set things up simply on a budget, especially if you can pull the subframe all in one and deal with the suspension all in one. Plus, if you were ambitious you could easily have 4 wheel steering. :)

Weather Spotter- I have been following that build, but his build is definitely a step up from what I had in mind. I'm going to be using metal a lot more in my build. I'm not too confident in my fiber glassing skills and metal is something I know well

2000neon- I may move the ducts closer to the front before the car begins to taper in, but the edison2 VLC did it, and it worked for them. I don't think I'll be doing rear steering, but it is definitely possible.

The biggest problem I've run it to is the front glass. I'm pretty sure I need to use tempered glass my law but I can't find any cars with the right shape glass besides the aptera glass.

If I had the skills, time and money my answers would be

1. 4 wheels, a full compliment seems ideal. A mid-engined layout lends itself to mounting an FWD powertrain behind the seats with the steering locked. If you get 2 subframes from an FWD car you get both ends. The MGF was made this way :

http://www.carpages.co.uk/mg_rover/m...e_23_07_04.jpg

It used the front subframe of one of these at both ends :

http://i4.photobucket.com/albums/y10...GTi_red_vr.jpg
(this is what we in the UK know as a Metro...:D )

2. Tricky. Diesel is automatically better on MPG but worse on emissions and in some cases weight and reliability issues such as DPFs. I used to run a TDI here in the UK but all new Diesels have a DPF so I switched to petrol. On the plus side they can run on refined veggie oil for low $$s and have more driveable torque profiles.
If you go Petrol then smaller and more modern the better - maybe a Smart engine (watch for wear / oil consumption on earlier ones) or Geo Metro / suzuki 1.0 & 1.3 units. Also look at the smaller Toyota, Kia, Nissan etc. engines - somewhere between 1.3 and 1.5 would be ideal.

This will be driven more by what you have available locally than a general question I suspect.

3. If you go Diesel then turbo, if petrol then N/A. Turbo on a diesel makes it more driveable and can positively affect MPGs in normal driving and they tend to be more modern (TDI etc.) and FWD/transverse format. An NA diesel is more flexible on fuel and cheaper to buy but also heavier - think more truck engines than car ones.

4. The more modern your engine is then you gain more than you lose.
You gain the OBD2 stuff (readings and ECU) plus better FE and more power.
You lose based on complexity (more electronics) and also when makers link things like security (immobilisers) to the engine management system so it makes it more complicated when you use the engine in another vehicle.

Seems like I'll be going with a 90-95 metro 1.0L 3 cylinder mated to the manual tranmission from the 4 cylinder for the taller gearing. I'll also be going with the Xfi cams and ECU. It would be nice if I could find an Xfi engine with the lighter pistons, but metros are a dime a dozen here while the xfi version is not.

I most likely won't be using airbags due to the added complexity, but I'll have a large crush zone in the front and a 5 point harness. NASCAR doesn't use airbags and only recently began using head restraints because they have high speed crashes.

is this an all out mpg car? seems so because you chose the 3cyl. are you going to modify an existing car?

i've considered it a few times, if i were going to spend the time, effort, and resources to build myself a car. it would have to be fun to drive. i think either taking an aero sedan and making it a small truck or using an old dodge rampage as a base and putting a v6 in it with a tremec 5/6 speed would be ideal. im confident a good v6 in an aerodynamic vehicle with the proper gearing could easily do 50mpg highway.

This will be an all out MPG car but within the reason of about a $5000 budget.

I will probably be using 2 metros as parts cars, but most of the car will be from scratch.

1 metro will be for the 3 cylinder engine
The other will be for the tall geared transmission.

I'm hoping the car will be fun to drive due to a low weight, good aerodynamics, a lowered suspension, and good weight balance. Worst case scenario I'll have a 4 cylinder engine and a shorter transmission which I can mix and match with to find a good combination of speed and MPG.

People who have mated the 3 cylinder to the taller transmission have said there is some driveability problems, but I'm going to have a lower weight car than they had and rear wheel drive, so we'll have to see how it goes.

If you want to build the ultimate MPG/Aero car an alternative approach would be to get a Metro or a Civic and play with the aero. It will be cheaper because parts just bolt on and there isn't anything which mechanically hasn't been done before - things like the 3 cyl with the longer gearing. You could gain by being the lightest or the most aerodynamic as a lot of those types of vehicle have to retain seats or carry stuff.

Search for the Aerocivic thread and follow that if you haven't already.

A mid engined car using Metro bits might be a lot of fun though.

I have already modified a car. But I'm more into the challenge of building a car than anything. Plus, if I build the car from scratch, then everything can be the way I want it.