I’m part of a student run race team currently designing the body for our car this year. Previous cars have used wet layup or alternative materials but this year I’d like us to try a resin infusion process. Really I need feedback on if I’m missing any steps/materials or overlooked anything because we’re on a budget so we try to avoid major errors if possible. 
So here is our setup – we have a body computer model being developed. The model will be divided into 2 parts and 2 negative molds CNC’d in our machine shop. (We decided making a plug then mold then infusion would take too much time and money.) The molds will be machined at a high detail then hand sanding to the best possible finish. We’re still undecided on if the mold will be out of foam or MDF wood (I’m leaning towards mdf.) Either way it will be multiple panels glued together to the needed thickness.
The plan is to paint tooling gelcoat into the mold (so the final part surface will have a glossy finish) – we are not very concerned about the reusability of the mold, part of the competition is building new cars every year. However if we do mess something up it’ll be good to not have a ruined mold. We’re going with painting it on because we don’t have a spray gun and can’t justify buying one til we prove the process works.
Once the gelcoat fully hardens (would give it a week+) wet sand any imperfections and polish to glass finish. Use release wax (4+ coats?) – From what I’ve read we’ll stay away from PVA and stick with just wax. Then:
Lay in 1 layer 6k 4HS carbon fiber
Lay in core material to reinforce weak spots (leaning towards divinymat)
Lay in 1 layer 6k 4HS carbon fiber
Lay in 1 layer peel ply
Lay in 1 layer flow media (not sure which yet)
Lay in Inlet Tubing (leaning towards enkajacket or spiral tubing)
Lay in Outlet Tubing (would love MTI if we can find an American supplier otherwise we’ll go with spiral tubing and make our own resin traps)
Lay in bagging film (we have left over strechlon 200 but after some mixed posts on here we’ll consider alternatives like double bagging or bite the bullet and buy new material)
We’re going with only 2 layers of carbon fiber because it does not need to be structural but does need some stiffness and to be able to withstand impact forces of unlucky orange cones. 
We’re planning on limited use of spray adhesive; given the mixed results on here I’d like to find better alternatives however we do have a lot of complex curvature so it may be needed. I’ve seen some mention of using clear gelcoat and or airtack both seem like possible solutions we need to test with. Would the gelcoat bond with the mold that has gelcoat on it or will the wax act as a barrier to keep them separate?
As far as our vac setup - I need to check what our shop air and venturi can pull and we have a secondary vac available we might set up depending so I’m not very worried about getting down to the pull we need. This will be a rather large part (estimated around 9ft x 5.5ft) so we’re still debating tube configurations. Running MTI or spiral tube around the perimeter of the mold and run a feed line straight down the middle seems like our best bet.
Given the size of the part we’re planning on using resin with at least a 60min pot life, I don’t know how long it will take to infuse but we have no experience on speeds and would rather be on the safe side. The resin/hardener we were looking at was in the 900cps range when mixed which after reading a lot on here is not what we want, so any suggestions on much lower viscosity systems would be appreciated. We’ve never bothered with degasing before but since we can weld together a pressure vessel pretty easily I’m going to push to have one made for a degas process.
There’s been some debate on how we can get such a large part to release and if release wax will be enough, we’re totally open to suggestions. So far jamming wedges in and blasting shop air into the gaps has been the only real suggestions floating around. Post release trim/polish/clear coat depending on how well it comes out.
We’ll be experimenting with the process in the coming months on a smaller scale and I’ll be sure to update this thread with pictures as we progress.
Thanks for any help!
-Dave