What would you build?

evolutionmovement · Post by **evolutionmovement** » Fri Oct 19, 2007 5:00 pm

I noticed the thread about other cars has several mentions of building cars. Curious as to what people want to build.

I have a few dozen hotrod things like a Sonnet III with a Honda engine and stuff like that, but I'm talking about whole cars you'd build. It could be something completely your own (within reason, of course, as there's some excellent engineering already done and tested sitting in junk yards all over and obviously nobody's going to sand cast their own engine block and heads.) Or it could be like my friend who built a Birkin with a 250 HP engine (!). It's kind of a kit car, but it's still pretty much scratch built so that would count too.

I want to build a series of tadpole 3-wheelers (something along the lines of a T-Rex or Grinnall Scorpion, but practical).

Originally I was going to buiild a car with a Cessna 150 fuselage and a Goldwing drivetrain and two front wheels, but the DMV didn't like the side-by-side seating, car controls, and the acrylic windshield, so I binned that. Plus it would resemble a strange 3-wheel deuce coupe.

So the plan now is what would resemble a Focke-Wulf 190 with the tail cut past the cockpit, DOT-approved 3-piece windshield, rear wheel covered by body work. I hope to be able to design the NACA cowl covering the radiator and A/C condenser to function for forward thrust in the 80 mph range (realistic cruise speed). I'm working on a version that's a single seat and a tandem 2-seat. 12 gallon fuel cell to try for a 600 mile range. The aim is a solid, fairly quiet, comfortable, fast, cheap, efficient car with exceptional handling and braking (it should be able to pull well over 1g lateral. The T-Rex pulls nearly 2).

It will be about the same size as my Mazda 3 in length and height, but wider track in the front. The size is necessitated by proportion and the need to run a prop shaft under the seat and enclose the underneath of the car with bodywork, like an aircraft, as well as the safety that comes from being big enough to be seen. I don't think it could be missed. The wheels in front would stick out like a formula car, covered in fixed fenders housing extra lights (having them turn with the wheels was considered, but would be too much unsprung weight and housing the headlights in it would be damn cool, but might be a legal mess and there'd be no way to stop them bouncing all over the f'n place on bumps). No doors, so the chassis can come up much higher for strength, safety, and to reduce the chance of rattles and squeaks. To enter, the canopy and part of the bodywork (I had to cut it lower so I wouldn't have to use a ladder to climb in and out) would slide back by electric motor controlled by a remote key fob. No key to start it either - the remote would have a button that would trip a relay to allow the car to start. So I'd have a 'stop/start' button, but it would have a purpose. I hate keys.

The chassis would likely be steel tubing, though I'm seriously contemplating a bonded and riveted alloy one much like the Lotus Elise if I can find a source for the complicated extrusions they use. There's a lot to it, so it will probably not happen, but it would be a hell of a selling point as I plan on trying to sell it to some rich prick who wants a unique toy. I'm sure I'll run into one somewhere. I'm sure I'll run into all kinds of people asking a million damn questions, but that's the price of what I want to achieve. It's another good argument for the long range - less chance of encountering humans.

The drivetrain, front suspension and steering parts would be Honda S2000 2.0 with a Goldwing rear (and subsequent higher FD than the S2000). The seats and some of the interior would be from the crashed donor as well. I'd like to get a different gauge set, but I doubt I'll have the budget. I'm waiting for someone to come out with a programmable LCD display that lets you design your own gauge cluster, maybe switching between styles on a whim. It would just need to pull information from the ECU. I have no idea why it hasn't ben done yet, but I'm no programmer, so I can't do it myself. By the time I get a chance to build this, they'll probably have been out for ten years.

The successful aesthetic design of a 3-wheeler is difficult as the proportions are odd, so I chose an aircraft resemblance for aerodynamic efficiency, the fact that I've always loved old piston-engined fighters, and that an airplane is a familiar shape, which should make it look less strange in peoples' eyes. The tall rear married to the wide front should balance it well visually and the scale drawings I'm doing to produce a model off of bear that out (at least to me). Original designs called for a vertical tail fin housing the vertical brake light, but that would either make the car as long as a plane or interfere with the cockpit sliding back (a feature I refuse to let go of as I can drive with it open, I hate conventional doors, and I just think it's damn cool to be able to enter and exit that way).

I plan on getting this registerable as a car to avoid legal issues that vary by state, like helmet laws and licensing. I chose 3-wheels for the weight reduction, strength increase, ease of engineering vs. 4, aerodynamic benefits, and vastly superior turn-in and road holding.

So what are you other garage design-engineers planning/building?

internetautomart · Post by **internetautomart** » Fri Oct 19, 2007 7:18 pm

I's build something ala' XR311, but on a smaller scale.

PhyrraM · Post by **PhyrraM** » Fri Oct 19, 2007 8:55 pm

I've already commited myself to building a Locost 7 after the Legacy is running well.

Mine will be a modified 'book' frame using Miata suspension and brakes. Power will come from a '89-'85 T-bird SC. Should be around 300hp/400lb.ft. Hoping to keep it under 1500 pounds.

The frame will be modified to greatly increase stiffness. It will also be a few inches wider and slightly taller than a book frame.

The engine will be mostly stock with a custom camshaft that will raise the powerband to the 5500-6000 RPM territory. This should shed enough low end torque to make it bearable and fun in such a lightweight car. Heads are stock with only a slight unshrouding of the valves and valvesprings to support the new redline. The supercharger is a higher flowing unit from a '94/'95 'bird. Lightweight flywheel and pulleys, a fully balanced bottom end and ARP rod/main bolts also help the redline increase. Engine control is the stock EEC-IV unit, which is cracked and freely reprogramable. Stock T'bird SC 5 speed.

The suspension is all Miata with fabricated control arms. Miata power steering rack, converted to manual. MX-3 steering column and wheel, because they look nice. 2nd gen RX-7 rear diff because it is compatable with the Miata halfshafts and has a factory clutch type LSD. It also is longer so no need to fabricate a torque arm like a Miata diff would need.

Only things I need to figure out still is brakes and pedals. Prolly go with stock '94-up Miata brakes for now. Prolly go with 3 Tilton style independant master cylinders with a balance bar between the front and rear. 3rd is for the clutch. Seats will be whatever is available and price right when the frame goes together. Stock Miata seats are an option. Gauge cluster will prolly need to be something from a late '80s to mid '90s Ford to work properly with the powertrain. Maybe a Probe or something, we'll see. Also haven't figured out what do do about the intercooler. Probably won't be able to untill I see how the engine sits in the frame.

I've been planning this for a long time and 80% of it is in the garage, waiting. I just seem to always gravitate to a Subaru when the garage is free.

jamal · Post by **jamal** » Fri Oct 19, 2007 9:49 pm

evolutionmovement wrote: I chose 3-wheels for the weight reduction, strength increase, ease of engineering vs. 4, aerodynamic benefits, and vastly superior turn-in and road holding.

Vastly?

At a glance, to me, it seems that a three wheeler will be less stable and handle poorly. Especially if you have a fairly even weight distribution. Motorcycle tires generate lateral grip through lean angles; car tires generate grip with slip angles.

I just want to take an old Impreza 2-door and do an 05-07 STi swap.

evolutionmovement · Post by **evolutionmovement** » Fri Oct 19, 2007 10:40 pm

This is not a motorcycle. It won't have motorcycle tires. It is a car with a central rear wheel. I'm not sure why I'm the only one a 2+1 3-wheeler's handling superiority seems natural to, but apparently I'm rare as I've had to answer this question a million times to people since I've talked about my admiration for the Morgan Trike. Maybe watching grainy footage of one on a track passing much higher powered machinery in the thirties gave me the correct impression to begin with.

Mine might not generate the grip of the T-Rex, but I will have more weight in the front, which is preferable in a tadpole 3-wheeler to prevent the inside front lifting in high g turns. The T-Rex pulls 1.9 lateral gs. I don't know of any production street car that gets near that.

Here's something I grabbed off the interwebs. It seems to be written a while ago, but physics hasn't changed much, just technology:

Designing to the three-wheeler's inherent characteristics can produce a high-performance machine that will out corner many four-wheelers. A well designed three-wheeler is likely to be one of the most responsive machines one will ever experience over a winding road. Superior responsiveness is primarily due to the three-wheeler's rapid yaw response time. Yaw response time is the time it takes for a vehicle to reach steady-state cornering after a quick steering input. A softly sprung four-wheeler will have a yaw response time of about 0.30 seconds, and a four wheel sports car will respond in about half that time. A well designed three-wheeler can reach steady-state cornering in as little as 0.10 seconds, or about 33 percent quicker than a high-performance four wheel car. Quick steering response has nothing to do with the number of wheels or how they are configured. It is a byproduct of reduced mass and low polar moment of inertia. A typical three-wheeler is lighter and has approximately 30 percent less polar moment than a comparable four wheel design.
A conventional, non-tilting three wheel car can equal the rollover resistance of a four wheel car, provided the location of the center-of-gravity (cg) is low and near the side-by-side wheels. Like a four wheel vehicle, a three-wheeler's margin of safety against rollover is determined by its L/H ratio, or the half-tread (L) in relation to the cg height (H). Unlike a four-wheeler, however, a three-wheeler's half-tread is determined by the relationship between the actual tread (distance between the side-by-side wheels) and the longitudinal location of the cg, which translates into an "effective" half-tread. The effective half-tread can be increased by placing the side-by-side wheels farther apart, by locating the cg closer to the side-by-side wheels, and to a lesser degree by increasing the wheelbase. Rollover resistance increases when the effective half-tread is increased and when the cg lowered, both of which increase the L/H ratio. A simple way to model a three-wheeler's margin of safety against rollover is to construct a base cone using the cg height, its location along the wheelbase, and the effective half-tread of the vehicle. Maximum lateral g-loads are determined by the tire's friction coefficient. Projecting the maximum turn-force resultant toward the ground forms the base of the cone. A one-g load acting across the vehicle's cg, for example, would result in a 45 degree projection toward the ground plane. If the base of the cone falls outside the effective half-tread, the vehicle will overturn before it skids. If it falls inside the effective half-tread, the vehicle will skid before it overturns. To see a drawing showing a base-cone illustration of single front wheel (1F2R) and single rear wheel (2F1R) vehicles, click on: Single Front & Single Rear Wheel Comparison (23k). The single front wheel layout naturally oversteers and the single rear wheel layout naturally understeers. Because some degree of understeer is preferred in consumer vehicles, the single rear wheel layout has the advantage in this department. Another consideration is the effect of braking and accelerating turns. A braking turn tends to destabilize a single front wheel vehicle, whereas an accelerating turn tends to destabilize a single rear wheel vehicle. Because braking forces can reach greater magnitudes than acceleration forces (maximum braking force is determined by the adhesion limit of all three wheels, rather than two or one wheel in the case of acceleration), the single rear wheel design has the advantage on this count as well. Consequently, the single rear wheel layout is usually considered the superior platform for a high-performance consumer automobile. But much depends on the details of the design.

SuperRallyRoo · Post by **SuperRallyRoo** » Fri Oct 19, 2007 10:55 pm

When I turn 25 and get a small grip of money... A wide body 1983 toyota starlet with a Ls6 supercharged corvette V8 in it.

PhyrraM · Post by **PhyrraM** » Fri Oct 19, 2007 11:19 pm

You seen this yet?

http://spyder.brp.com/

My mom (yep) is on the waiting list. My brother-in-law has rode it at the factory demo day. FWIW, He said it was amazing.

Redneck Wolf · Post by **Redneck Wolf** » Fri Oct 19, 2007 11:59 pm

I'm not much of a Honda person, but I thought it would be cool to make a drift car like an AE86, but using an 88 Accord hatchback, and putting an S2000 engine and drivetrain in it.

entirelyturbo · Post by **entirelyturbo** » Sat Oct 20, 2007 12:32 am

I've given some thought to this, but I unfortunately don't have enough of an imagination or knowledge of engineering to come up with anything worth pursuing.

I do plan on taking care of that engineering part though...

I do feel though that I would probably use a Subaru FWD drivetrain and mid-mount it. I may be losing my interest in new Subarus, but that doesn't mean I don't like the engine. To me, a Subaru FWD drivetrain just seems too perfect in a mid-mounted position. The ONLY thing that could cause problems would be designing the shifter, and cooling of course.

I would probably go the diesel route too, if and when Subaru's diesel engine comes out. Just like everyone else these days, I think diesel engines deserve the rediscovery they've enjoyed the past couple years, and the benefits of a boxer engine seem like they would complement the diesel design perfectly.

As for chassis stuff, hmm. I'm not enough of a suspension expert, but I would probably go elsewhere than Subaru for suspension. Don't get me wrong, I think Subaru's suspensions do a nice job of providing a balance of handling, ease of maintenance, and ride comfort. But if I'm building a car that's focused on performance, I can give up the latter two.

Call me plain and uninteresting, but I think I'd stick with four wheels. Four wheels have been good to me, and if it ain't broke, I'm not going to fix it.

I would probably make it just a one-seater. I'm used to driving by myself. I can drive with other people in the car, but I'm happier driving by myself.

Maybe when I go back to school for engineering, I'll come up with something more organized. But right now, I'm too burned out from life sucking to do any daydreaming.

Steve, while I'm thinking about it, have you run into any other hurdles in the registration process, such as the car not having a VIN number or something like that?

SuperRallyRoo · Post by **SuperRallyRoo** » Sat Oct 20, 2007 12:32 am

Those spyders are frikin sick!

evolutionmovement · Post by **evolutionmovement** » Sat Oct 20, 2007 1:08 am

An inspector assigns a VIN upon passing inspection (lights, etc.). It's the same thing they use for scratch-built hotrods, customs, and kit cars. Were it remotely normal looking I could have probably just used the wrecked S2k's VIN, but it won't look anything close to a reasonably believable custom version of the Honda. My problems had been trying to get it accepted as a motorcycle (as most states would automatically classify it), but they took issue with the planned Cessna's car resemblance by description. So I went with my original preferred idea for a completely new vehicle and after rethinking things, I am going for car registration to hopefully reduce hastle with cops later. If the registry still wants to call it a bike, they can, but with the safety glass and wipers I cover all my bases. I originally wanted a large bubble canopy, but again, acrylic windshield=no good. The flat glass I'm going with will reduce distortion anyway and give it a more bad ass look.

Scratch buliding a 4-wheeler will require a LOT more work and experience as it's not just an extra set of wheels that interact with each other, but that interact with the front in much more complicated ways, and also put a lot more torsional stresses on the chassis. Better packaging and easier for humans to comprehend, though. That damn enclosed rear wheel on my 3-wheeler (I'm caling it Cerberus) eats a lot of cockpit volume (which a possible passenger will have to deal with if I do 2 seats). The passenger will sit in back like in a Messerschmitt bubble car with their legs astride the front seat. Only women ride for free.

The Can Am looks cool. Defintitely more a motorcycle. Has anyone seen the tilting Carver 3-wheelers? They're traditional trike style, so they look really odd, but they look like fun. There's all kinds of stuff on Youtube. Not many quality T-Rex videos though. Just morons cruising or doing burn outs. Whoopie, you can light the rear tire on an 800 lbs. car. I want to see good track footage, dammit! There's some spectator footage of a Grinnall Scorpion on a track.

The OSCA 2500 GT was supposed to be a light-weight sports coupe with a mid-mounted Subaru drivetrain. They only built a prototype or two.

denver_whitest185 · Post by **denver_whitest185** » Sat Oct 20, 2007 1:21 am

Redneck Wolf wrote:I'm not much of a Honda person, but I thought it would be cool to make a drift car like an AE86, but using an 88 Accord hatchback, and putting an S2000 engine and drivetrain in it.

why don't you just build an AE86. a 4AGE can make 300+ boosted and built right and can rev to 10k

ive got a couple projects i really want to do. right now since i don't have lots of money being free, so i'll have to be content with being involved with formula SAE

Redneck Wolf · Post by **Redneck Wolf** » Sat Oct 20, 2007 1:26 am

denver_whitest185 wrote:
Redneck Wolf wrote:I'm not much of a Honda person, but I thought it would be cool to make a drift car like an AE86, but using an 88 Accord hatchback, and putting an S2000 engine and drivetrain in it.
why don't you just build an AE86. a 4AGE can make 300+ boosted and built right and can rev to 10k

ive got a couple projects i really want to do. right now since i don't have lots of money being free, so i'll have to be content with being involved with formula SAE

Just was thinking of doing something different.

denver_whitest185 · Post by **denver_whitest185** » Sat Oct 20, 2007 1:40 am

Redneck Wolf wrote:
denver_whitest185 wrote:
Redneck Wolf wrote:I'm not much of a Honda person, but I thought it would be cool to make a drift car like an AE86, but using an 88 Accord hatchback, and putting an S2000 engine and drivetrain in it.
why don't you just build an AE86. a 4AGE can make 300+ boosted and built right and can rev to 10k

ive got a couple projects i really want to do. right now since i don't have lots of money being free, so i'll have to be content with being involved with formula SAE

Just was thinking of doing something different.

well, it could be a pretty cool, unique project. i don't know what kind of rear subframe your going to fix in there to make it RWD though, along with engine mounts and suspension. it defiantly would be different

PhyrraM · Post by **PhyrraM** » Sat Oct 20, 2007 1:47 am

If I didn't already have a spare SC engine from when I owned a '90 Supercoupe, a mid mounted Subaru would have been an EASY choice for my project. I completly agree, it's perfect. Add a custom oilpan or dry-sump and get that CG even lower!

The nice thing about a Locost 7, is than much of the real 'math' engineering has been done already. Folks have found ways of stiffening the chassis 2-3 times as stiff as the book. Only adding a few pounds to boot.

evolutionmovement · Post by **evolutionmovement** » Sat Oct 20, 2007 2:17 am

I was originally thinking of redesigning a 7 type thing myself for more day to day practicality, but got intrigued by the idea of implementing the NACA cowl on a car. My friend's Birkin was insane. I still don't understand why he sold it (he'd 'kill himself' shmill himself) and he says everything else feels overweight and slow now.

PhyrraM · Post by **PhyrraM** » Sat Oct 20, 2007 4:32 am

Everytime I think about building a 'practical' car I come to the realization that the one thing that auto manufactures do best is exactly that, build practical cars. Most self-builders simply do not have the resources, time, deication or even desire to match OEMs as an entire package.

Homebuilts, on the other hand, can be pure, single purpose cars. No need to accomodate a wide variety of people. No need to cater to those that prioritize one design aspect over another. No marketing research to dilute the ultimate goal for a car. No need to sell more than one, or any at all. In that respect, most of us can far surpass all but the most focused and expensive cars and makers.

douglas vincent · Post by **douglas vincent** » Sat Oct 20, 2007 5:30 am

I would like to build a larger Locost on a subaru frame for the AWD effect, and of course, the easy 300 whp you could get.

Next, I have always wanted to drop a 472/500 Caddilac motor into a 1978 Subaru Wagon midengine style.

And lastly, do a drivetrain swap of a AWD modern legacy into the above wagon.

Manarius · Post by **Manarius** » Sat Oct 20, 2007 5:46 am

If I had a lot of money, I'd try to twin-turbo a SVX and then attach a STI 6MT with DCCD. Sounds like a big pain the ass, but 500chp in an SVX? Heh.

evolutionmovement · Post by **evolutionmovement** » Sat Oct 20, 2007 5:47 am

I disagree to an extent. Practical cars today are built to pass ridiculous safety standards and fit the boring mentalities of people who prefer comfort over freedom. As a consequence, a 2003 Camry SE weighs the same as a 1970 Plymouth Road Runner. I want a car with weather protection, no doors (I hate doors), efficient aerodynamics, cheap to run, quick, fuel efficient, fun to drive even at low speeds, and in touch with the road (like with a manual rack). Light weight pretty much gives me the last five. What I don't care much about (but every maker gives you now) is safety (though the cage/chassis should be pretty tough and I'll be using the airbag and ABS of the Honda, the latter to give me some brake tuning leverage since I'll have nothing to go by as a base to determine bias), passenger carrying ability (95% of the time I'm driving alone with a bag of tools), and electronic crap. I also am free to style this in a manner that eschews in-the-box thinking to fit the characteristics I want, not a committee vote to appeal to the maximum number of people. My requirements are fairly unusual so nobody's going to build what I want.

So, yes, it would depend on your definition of practical, I suppose, but it comes down to me being able to build what I want over what a bunch of people with limited imagination want to sell (which we agree on). To me practical means: comfortable to spend hours driving (climate control, reasonably quiet, and decent seats and storage compartments), cheap to run, easy to fix, weather protection, some useable turning radius and ground clearance, and fuel efficiency. So mine won't be a pure performance machine, but I believe my compromises are small enough that the huge performance potential I'll reduce will still leave me with something excedingly impressive, yet fit my requirements for practicality. The calculations on my worse case scenarios for power and weight give me a 0-60 in the mid 4's. I wish I could find a mileage calculator that works to at least give me a ballpark. I think I could come up with a formula, but can't find the information I think I need. I need to write up a calculator for lateral g's, though I'm not sure how exact it would be without the drivetrain and borrowed chassis parts to figure geometry and cg from.

My Achille's Heel (quite literally) may be the Goldwing rear end. I can't find any reports of them blowing, but there seem to be very few modded Goldwings. I'm hoping the modest torque of the 2.0 won't be a problem. I'm having it cryo-treated anyway.

206er · Post by **206er** » Sun Oct 21, 2007 6:19 pm

volvo 142 or 122 with LS1/T56/ford 9" and some T5R wheels
RPU rat rod with a single turbo'd/LPG SBC and full manual TH400, totally unsafe
honda CR500 road race bike
RD350 cafe bike

shtbxr22 · Post by **shtbxr22** » Sat Oct 27, 2007 10:46 pm

I want to put a ~98 Ford taurus SHO V8 powertrain in a 88-91 CRX

. I wrote in to sport compact car magazine about it, and after they made fun of me for it, they actually told me what to do.
"square peg, round hole" in the issue where the EVO X is on the cover.

beatersubi · Post by **beatersubi** » Sun Oct 28, 2007 4:23 am

What about a Ariel Atom/Lotus Elise type cross w/ a mid-mounted (below the rear of the seat(s) even) Subaru or Porche turbo'd four, or flat six, mated to a transaxle driving the rear wheels?

edit: basically like a Boxter

evolutionmovement · Post by **evolutionmovement** » Sun Oct 28, 2007 4:06 pm

The stillborn OSCA 2500GT was such a car. More an Elise than an Atom, though.

beatersubi · Post by **beatersubi** » Mon Oct 29, 2007 4:33 am

I like the functionality look of the exoskeletal frame on the Atom.
However, were it to have a boxer engine it would have to be longer than an Atom due to the engine/tranny layout. Better high speed stability, I guess. And lower c/g.

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