Homemade CFRP mid engine sports car

[Paul Bristo]

Hi everyone, i've been enjoying this site for a few years now and reading about all your builds, so I thought i'd post my own project. I've been designing it for a few years now and this year I started the build. It was originally going to be a GT40 replica but my wife convinced me to try and do my own style.

The main structure and body panels will be CFRP. I have plenty of experience designing CF structures but not so much actually making them myself .. so wish me luck. The current plan for powertrain is an LS3 with porche/audi transaxle, but i'm several years from that stage of the build so things might change.

One of the main goals of the project is that its something to do with my kids, and so i'm going to take it slow and enjoy it. I expect it to be a very long road, the plan is to finish in less than ten years

 

[Paul Bristo]

Some photos so far;

building a buck of the outer body panels from wood & foam & plaster. Will then cut into front clam / rear clam / mid upper and take some fiberglass moulds

 

[Paul Bristo]

 

[Neil]

Paul,

It is good to see someone who is designing his own body style. It is a lot of work but when you are finished it will be totally unique.

My advice is to not get ahead of yourself. The choice of engine and transaxle will dictate the minimum outline of the rear of the car. The driver's seating, pedal location, radiator, & wheel size, wheelbase and track will complete the envelope that you must work in. You don't want to put all your effort into building a beautiful one-off body only to find out that something important doesn't fit.

Your design is heavy on air scoops & ducts; those will add lots of aerodynamic drag. Nice work on the body buck.


Regards, Neil Tucson, AZ

 

[Joel K]

That’s quite an ambitious project. Looking forward to following along. Also, the design is very nice.

 

[Lenny D]

Wow! That is super impressive.

What CAD software are you using?

 

[Terry Oxandale]

Can't wait to see some tub work.

 

[Jasper]

holymoly.. thats some project to undertake. Love the unique look of the body, but you'll have to do some very expensive engineering for the structural components (i.e. CFRP chassis, right?) Are you going with vacuum assisted resin transfer? I take it you don't have prepreg and autoclave in mind?

 

[Randy V]

Fascinating project!
Glad to see you have your children involved with the project!

 

[Paul Bristo]

Can't wait to see some tub work.

you and me both !

Neil - yes you are right, all the openings will not be great for aero drag. I decided at the start that I was going to favour aesthetics over aero performance, in the early days I did start some CFD but dropped it when I realised I didn't care so much about it. The openings will help me with cooling too, i'm a bit worried about cooking the CFRP resin (I'm going to need to use low temp ones)

Jasper - Yes, plan is to use resin infusion, I've seen some very good results from this in the past. Wet layup is a very last resort plan B. I plan to practice a bit once I get to that stage.

 

[Jasper]

resin transfer can work fine.. Strength/weight wise it is almost as good as prepregging.
You need a lot of consumables, and the best advise I can give you: Build your moulds with plenty space for your peel-ply, tack-tape, breather cloth etc.
You run out of space quickly with all of these additional materials, so a 10cm wide flange all around your part is about the bare minimum I think. Also make sure you find a good supplier of RT-resins, that can supply you with the right viscosty resins.. it is an absolute pain otherwise.

Please keep us in the loop, looks very cool.

 

[Mesa]

I could get myself in serious trouble looking at this kind of stuff. One of my bucket things is to do my own body...you are NOT helping

Kids grow fast, they may or may not have any interest in Dad's project. But hey, it is a great way to expose them to your interests and see if they catch on!

 

[Jim B.]

did you hand cut all the wood splines? what CAD did you use to slice the model?

 

[Chris Kouba]

Hi Paul,

What is your plan for a windshield? Laminated glass or are you planning on something plastic?

 

[Paul Bristo]

A local firm waterjet cut the wooden formers for me from thin ply, there were over 300 in all, too many to mark out and cut by hand

The windshield is from a lotus elise, it was the first part i bought. I spent a long time looking at cars in car parks trying to decide which had the right shape I wanted!

 

[Chris Kouba]

Nice work! I've had a similar concept brewing and in all the calories I've spent on it, that screen was one of my leading contenders as well. Should make an excellent shape to integrate with your bodywork. Really looking forward to seeing your progress!

 

[Paul Bristo]

So .. bit of an update. This month has mostly been sanding, more sanding, and even more sanding.

I finished the rear clam area and decided to separate it from the rest of the buck so I can add mold edge flanges and repair any damage before I prime it and sand to finer grits. I had some fun with a laser level to get the split lines straight. The cutting process was easier than expected, not too much damage around the cut edges, and thankfully the two halves are still very sturdy after being split apart.

hoping to get the flanges on quick so I can paint the primer on before the weather gets too cold to use it .. and I don't have a heated garage

Looking forward to getting the rear clam moulded and off the trolley .. the car is too long to fit in the garage and comfortably work around it !

 

[Joel K]

Very nice!

 

[Paul Bristo]

So, bit of an end of year update ..

still working on the pattern for the rear clip but the end is in sight. Its pretty much all smooth and i'm now down to the finer grits to get the scratches out. Hoping to start fibreglassing the mold before the end of January, which i'm very much looking forward to. Pretty bored of sanding now, and not much opportunity to get the kids involved in this stage.



Lost a few weeks progress in November while I commissioned 'car project storage facility #1' .. so i'm all sorted now for space



Something else that I have set up .. albeit a little too late to catch the start .. a time lapse camera for the project. If anyone is just starting out in their project here's what i did; just a cheap go-pro knock-off with a remote for taking stills, so i can take one each day after working on it.

 

[Paul Bristo]

Been busy on the design side too, pretty happy now with the body structure. Stiff and strong enough and weighs less than i do .. which was the target .. and i an easier target now after christmas! changed the suspension around a bit too, inboard dampers still but actuated from the upper wishbone instead of a separate rocker and push rod.



Also been playing with different ideas for the front styling, was never 100% happy with the front end. Also, I need to cover the rear face of the front tyres for uk IVA, am undecided between some kind of upright mounted flap (like on a seven, could leave on or just IVA only), or make adding another panel to the side of the car ... what do you guys think ??