Pretty soon I am going to build a Lotus-7 Inspired sports car (more like a race car )

Anyways, if you dont know what a Lotus-7 is, they look like this:



Most of the cars today are Kit-Car's (somebody builds a frame and body, and sells it to you to put existing car parts in) most of the time they use Ford Cosworth engines, and alot of the for Sierra/Cosworth suspension and drivetrain parts. HP is in the ~200 range, which is alot for a car that weigh's less than 1500lbs.

Alot of people also build thier own from scratch, instead of buying "Kits", i am going to build mine from scratch since i already have a 135amp MIG welder and the skill to do it, and i also have the mechanicle "know how".

The frame will be designed by me using 3DSMax5, i have already designed and built 2 go-kart frames, they were super stiff... but weighed too much. (I undersestimated the power of steel when designing them) It will be a Triangulated Space frame using 1" 16gauge Tubular Mild Steel.

So, enough with the boring lecture, and on with some cool pics! (not my pics, just pics i used when designing the frame)







EDIT: i should also mention, they Whoop the Lotus Elise ass all over the place.

That sounds like fun.

Best of luck to you!

Important Design goals and considerations i want to be in my car.

Weight - Must weigh below 1500lbs, preferable closer to 1300lbs.
Power - Must have over 200hp, the higher the better.
Looks - Its gotta look good.
Cost - Has to be cheap (~$5000), good thing i have most of the drivetrain and tools and metal is cheap++
Speed - Must run at least 12's in the quarter mile, i dont expect it to run anything less because wheel spin will be a major factor in a light ass car.

Specifications:

LAYOUT:
Front engine, rear wheel drive

CHASSIS:
Comprehensively triangulated space-frame chassis. Additional stiffness provided by bonded & riveted aluminium panels

ENGINE: Turbocharged Chevy 2.8L 60degree V6 with all forged internals ARP main/head studs and Copper head gaskets; capable of over 500hp and 8000rpm.

TRANSMISSION: Turbohydramatic 700R4 with full manual Vavle Body and shift kit installed. (Basically an automatic transmision that you shift manually without a clutch, can also be paddle shifted)

SUSPENSION / AXLES:
Front: Equal Length double wishbone using LS1 Firebird front spindles, rotors, brakes and fully adjustable coil over shocks.

Rear: Fully adjustable 4-link suspension rolling on a Chevy 10bolt rear end with Positrac and 3.82 gears.

BRAKES:
LS1 disc brakes in the front and drums in the rear. (Possibly disc in the rear too)

here are some shots of the space-frame ive been working on in 3DMax:





This one has the drivetrain "roughed in"


this is a pic of how i want it to look: (mostly the hood scoop)

And it should be very cheap, considering i already have most of the (important) stuff.

Metal is cheap as hell, the metal i need is $1.02 per foot, and i will need roughly 200 feet. Which comes out to like $200, but since it is cheaper to buy in bulk, i can get 200 feet for $143. It is also very light, at 0.8264lbs per foot, if i used 200 feet of metal, the whole frame would only be 165lbs. Some people use aluminum instead of steel, but aluminum cost about twice as much as steel of the same strength, and i dont know how to weld it.

I already have the engine and tranny, i built both. I also have the rear end. My brother wanted me to build him a Turbo 2.8 firebird, but then he changed his mind and sold me all the stuff for $3000 (the engine alone is worth $6k)

The only difficult part will be the body work, since it will have to be made from scratch. Luckily fiberglass is easy to do, and my best freind brother knows how to do it.

Hopefully i can get this done in 12 months, its going to kick so much ass.

how much do you think it will cost to get everything done total? i've always wanted to build one too!

well, from past building experience, its the little things that jack up the cost.

For instance, when i was building my motor, the copper head gaskets were $200.

Going over this over and over again in my head... steering column would be like $300 (unless you use one out of a donar car), guages are expensive, fuel lines, fittings, brake lines, wheels and tires are like $1000, etc.

Like i said, it all adds up, im planning on getting alot of the stuff from the junkyard. If you were to BUY a kit car, it would cost alot more than building one, As long as you have a MIG welder and you know how to weld, you could build the frame easily.

In my case, its going to be under $5000, mainly because i can do all the work myself, and i already have an engine and stuff. But of course you could get a cheap 4cyl from the junkyard for cheap.

EDIT: And im not going to be using any super duper Baer/Willwood brakes, im just going to use some brakes that i can grab from the junkyard off an LS1 FBody, since they are rather large and work good, Same with the master cylinders and stuff.

if it looks like that red and black one thatll be hella tite :0

Reminds me of the Panoz Roadster. Looks like a lot of fun. I'm not sure I have the patience to build my own frame from scratch but I do love welding.

Good luck with it and post tons and tons of pics!

actually, the Panoz Roadster is a "Sevenesque", (a Lotus 7 style car) its too bad they fucked up the whole idea of the Lotus 7 when they made it. The Panoz weighs 2600lbs.

And yeah, im going to buy a camera before i start building.

ok, i found out exactly how much tubing i will need, and i need 176 feet of 1x1" 16guage mild steel square tube.

Each foot weighs 0.8264lbs. 176 x 0.8264 = 145.4lbs.

I will also need 10 feet of 1.5" 12guage 4130 alloy round tube for the rollbar, which is 1.44lbs per foot.

1.44 x 10 = 14.4lbs.

145.4 + 14.4 = 159.8

so its basiclly 160lbs for the whole frame. Its going to be like an oversized 300hp go-kart.

Its $126 for the square tubing, and $40 for the round, which comes to $146.

I dont see how people charge like $7000 for the kits when the materials are so fucking cheap. They must be charging like $50 an hour for the built time.

Those are like Exiges aren't they? Really good track cars...

All I can say is that you seem really well prepared and like you know what you're talking about, so that it will probably be a success. And that I fear I'm too tall to fit in it.

that chevy will have too much torque and really hurt the handleing
id get an I4 or rotary, something with more linear power delivery

BTW before i forget
I wouldnt trust a mig weld for a frame
arc it or tig it

I agree with william about the engine, although I have no idea about the welding comment.

almost all of these frames are made by MIG welding, you only need to TIG the suspension parts. (wishbones) And forget about ARC, its the worst of the bunch.

And this engine wont have hardly any low end torque because of the camshaft in it, its mainly for top end (5000-8000rpm) power. People put V8's in these things all the time, they handle them just fine.

EDIT: and its RWD, not FWD, torque wont do crap to the handleing exept make you spin out.

This reminds of Dennis from http://www.dpcars.net ... He's making his own car and it's astonishing.

that one is nice looking, and almost exactly what i want mine to look like. (with a different paint job)

Wow, great link. That guy's site kicks some serious ass.

my dads friend built a lotus 7 kit car. It weighs 900lbs and has a 6 cyl cosworth engine making over 300hp, I think teh engine cost him $50,000, crazy.

One of my fathers friends has one... with a Fiat 125 Sport engine (Webers, etc) and wanted to trade on my Fiat Panda because he needed it for his company, but I refused his offer... I love 7s, but they are so impractical it has to be your 2nd or 3rd car. BTW those are the cheapest sports cars in earth, here you can get one for 3000 to 7000 USD, with engines from Fiats 125s, Escorts, Bmws, or even Toyotas with the VVTL system...

Ok, here is the final frame design, i did alot of work to it. While doing alot of research, i found out that steel is almost 3 times stronger when pulled than pushed, so i revised it and turned all the "push" points into "pull" points, which also allowed me to save some weight by using less material.

I also revised the front suspension for better geometry, when the body rolls the wheels will roll the same direction the same ammount, which is not ideal, but its still pretty good. The ideal way would be to have the wheels roll the opposite direction of the body, but its impossible to do that.

For instance; if the body rolled in a turn 5 degree's (which it wont, its just an exageration) then the wheels would roll 5 degree's also. The suspension will be stiff, and the center of gravity very low, so the max roll i would imagine would be around 1 or 2 degree's. The suspension will also be fully adjustable for camber, toe, etc. So when doing some AutoX, i can increase the camber to compensate for the roll.

I also worked on the shoulder/butt area, which is now wider, about 2 whole feet of room. Wide enough for the largest bucket seats and big asses. (not that i have a big ass, i just dont wanna feal cramped) The engine bay is also slightly longer, which will allow a turbo to be placed in front of the engine.

The wheelbase is 99" and the track will be right around 50" (depends on how large the steering knuckle is) which is about normal for these cars. I am probably going to order some of the metal today, so i might be able to get started on it this weekend.

Here is what the final design looks like:

well id tig it
but whatever

the problem that is created by the abruptness or the torque curve is that as you turn you go up through the curve that sudden jump in torque will make you oversteer
id go with something linear


btw a good arc weld is > *

well i could convert my MIG to a TIG for like another $100... but i dont think its worth it. TIG's dont really have that much over MIG welds exept they look nicer, and are stronger on aluminum and stainless steel, im using mild steel. They also take longer to do. They can also weld really thin sheetmetal with minimal warping, which is why you see on American Chopper they use them on gas tanks and fenders, and they use the MIG on the frame and brackets.

ARC is the worst form, it uses no inert gas shielding at all, and purely relies on the flux in the rods, which is not very good. They do have gas based ARC, but that is called TIG.