So we kind of know that an ali frame wouldn't do, but how about bonding light PVC tubes together, cloth with pre-preg carbonfiber and put it in the oven ?

Not going to, just bored at the office ...

Cheers

Carbon fibre has a very high tensile strength (hard to snap by stretching) but it doesn't have too high a compressive strength. A space frame works in compression and tension.
A carbon fibre monocoque would be much better as it makes better use of the properties of the material.
It might be better to make a very light weight space frame and bond, or laminate carbon to it to give it torsional rigidity.

BTW, you don't HAVE to put carbon in the oven to cure the epoxy. you can do it at room temperature, it just takes longer.

Hm, if you use sheet CF to triangulate there's no room left for the rest ( plumbing, wires), It'll be a lot of drilling holes in the sheets.

The way to use composites is a monocoque, trouble is a Seven style shape is far from ideal for such a structure.
I you want to see a stiff proven composite monocoque sporsts car look at a Darrian or Davrian Mk8

oooh , look at the avatar .

anyway guys do a search , and youll find its been talked about a bit - it would have to be a bit of both steel/composite ,altho westfield did it - it was too expensive .

the traditional design doesnt help itself to making a composite structure , especially round the engine bay - you should be making bigger torsional boxes .

i wouldnt use PVC either , that would melt in an autoclave !!

i have my ideas , youll have to watch this space.

autoclaves don't need to be that hot. 50° is a good temperature to cure CF.

A monocoque or semi monocoque is not out of the question. Make the tub stop just behind the seats and have a small rear subframe for the rear suspension with a separate rear pannel and you've done the rear. Similarly, have a sub frame for the front suspension & rack and perhaps a cradle for the engine and you're almost there. The footwell fronts / sides / tops will add a lot to the stiffness, add box sections to the transmission tunnel and sides, plus one across the floor, under your knees and the cockpit will be sufficiently stiff. Add box sections in CF to the engine bay and you're done.

It would be a lot of work compared with steel. Whilst a CF car should be lighter and stiffer, are you sure it would be worth the extra effort?

its not worth the extra effort at the moment , it may feature in my first car , im not sure yet .

my idea is to have the moncoque extend to the mid point (engine mounts , and subframe from there - where do you stop tho , if i can make a subframe from there , why not back to the cockpit ? questions i keep asking myself , the crux of it isthe subframe mounting at the front would be what governs the strength of the monocoque , and trying to engineer it cheaply enough .

especially when my turbo sticks right thro where i would substantial strength !! , maybe the straight six NA engine i have would prove more suitable .

Westfield's FW400 was a carbon fibre thing....mad money although it looked smart.

I would think a cut and fold CF center tunnel, rear bulkhead, front bulkhead and sponses. Could bond in aluminium floors and sides and bolt on AL or steel subframes at either end. No autoclaving, complex tubing shapes, and as little CF as required to get the job done. Basically using the CF to pass the loads pickups to pick-ups through the center backbone. Just a thought. Cheers!

shhhh!

Yeah, that how it's done mostly in the formula student cars.