My engine bay cover development thread!

General Composites Discussions Composites Talk
#1

Hey all I’m in the works of developing my own Engine bay cover for a RX-7. I’d like to share with the community and track my journey. I’ve done a few Fiberglas projects using the wet layup method and can be seen here:
http://muibubbles-design.com/index.php?/juxor-v10/
^^ School project chair I designed and built.
Other FG projects on the site include, sub enclosures, and a 1/2 scale rear diffuser

For this project I will be using vacuum infusion and this is my first infusion part. any tips, suggestions or comments along the way is greatly appreciated!

So to start, these are a few inspirational pieces.
Panspeed

Knight sports

So lets get started!
Building the piece from scratch…
I did some rough mock ups with chipboard to get a rough template. It was too flimsy so I transferred it onto some scrap wood. it was still flimsy and heavy so i transferred it over to a FG sheet i laid up.

Next I began masking the engine bay off. (I know, I should have taped it up more but I got lazy, I will regret it later when i redo the engine bay)

The sheet i made was still a little too thin so I added a layer of the biaxial stuff. super thick

Test fitting and trimming the cut outs

laid up FG along the edges- this gives it dimension in another axis to help rigidity and ensures it tucks on the firewall nicely.
Things that need to be added
-All the straight lines need to meet back at the strut towers, this will complete the gap.

  • the cut out for the engine, needs a lip facing downwards.

This leaves me to where I’m at now. If you take a close look the right side sits 1/8"-1/4" lower then the left side, its driving me NUTS. I am designing this with the intention to duplicate and sell them. I want it to be FLAWLESS. Also since I didnt anchor/secure the “sheet” well, its not flat on the right side as well. So, I am thinking of cutting this one up to a flat sheet and transferring it to a 1/2" or 3/4" thick piece of MDF. This way I can use the thickness of the wood to created the bottom lip of the plug. Also this will give me a VERY good starting point as the mdf will be smooth an straight already. Or should i just cut the flanges off this piece and do it the same way but add a lip/flage for the fiberglass “sheet” to sit on ensuring it’s straight?

Thanks!:slight_smile:

#2

I would pick the side you like better and make the other side match. Cut along the 90* transition and raise or lower it to your liking.

The more you work it the thicker it will get, adding layers, body filler, etc. By the time you’re done your plug will be completely jacked up on the backside, uneven, different thicknesses, etc…but the side that matters should look proper. There is no art to plug making, just make it work with what you have. You could raise the entire right side with body filler if you wanted to. I wouldn’t want to do it that way since you have a nice flat surface as is. Easiest way IMO is to just cut it loose and raise the right side. If you lower the left side you have to fill the gap. If you raise the right you just have to re-set it and body filler the gap left from the cut.

#3

HeyBen thanks for the suggestions! I like your first idea, never thought of that. the only thing im worried about is if the when im bondo’ing the top surface to make it flat, the bottom will be resting on a table or surface that means when i sand it will be hard to figure our the true parallel plane. I’m thinking of cutting the lip off and just taping/gluing a lip all around the car’s firewall so the “FG panel” has something to rest on and ensure its leveled.

I’m starting to look for supplies and it looks like I will be ordering my material from uscomposites (carbon fiber, figberglass and resin (for mold)) and fiberglass supplies for my vacuum infusion stuff (peel ply, Resin (E15 8082) etc)

Any recommendations for a vacuum pump? is it possible to get something in the 100 range? Thanks!

#4

Harbor Freight sells pumps for under 100 and there are always some on craigslist.

Also look at soller composites and illstreet, all 3 are good shops.

Doing a part like that is tricky since you do have 2 surfaces to worry about. The top surface which needs to be smooth and aesthetically pleasing as well as the lip that will rest around the engine bay. Obviously if the part is infused from a mold the lip will take the shape of your final top dimensions. The second example you posted doesn’t rely on a lip like the first example.

#5

Will the HF one be strong enough for parts that are roughly 6sq ft?

anybody know anything about this one? the seller doesnt know much as it was his dads…
ITT Pneumotive Oil-less - $50
http://cnj.craigslist.org/for/3323393188.html

or
RobinAir 6cfm… $145
http://southjersey.craigslist.org/tls/3317122137.html

or
robinair 15400 $200
http://southjersey.craigslist.org/tls/3349565843.html

any recommendations or should i get a new one?

#6

Some progress today… Ordered all my supplies except for the pump. I bought it from Fiberglass supply.

Today i cut the flange off and sanded it down. I ended up hot glueing strips of wood along the firewall to have a “ledge” for the cover to rest on. In addition I hot glued aluminum angle on the underside width wise to prevent it from flexing.

added a few coats of fiberglass cloth an did a rough trim. I’m pretty satisfied with how everything has turned up so far. It is MUCH more leveled now and looks even. Now tomorrow will be the more challenging part, the mounting points and transitions to it.

Pics from today.


rough trim

#7

small update. I ended up snagging a robinair 6cfm vacuum pump for $115 (the guy was super cool). My materials is suppose to be here by tuesday but i find that highly doubtful since “sandy” will probably be making an appearance =(

on the other hand, finished designing, and laying up fibgerglass of the “rough” shape. Tomorrow will be trim, smooth everything out and make pretty!

some update pics because no thread is cool without pics!

#8

Is that thing supposed to do something or just hide the engine? If it’s not there… it doesn’t add any weight… anyway… good job so far :slight_smile:

#9

Nope, just clean up the appearance of the engine bay =)

#10

Been a while since I posted an update… The Plug is almost done… still doing some final sanding and filling the pin holes etc…

Sand, fill, Repeat.


getting there…

#11

Looking great man

#12

Cool project! i used to own a few FC’s and made triple gauge pods and vented headlight covers for them. Cant wait to see it finished!

#13

Thanks for the comment guys =)

This project wont be moving as fast since im juggling another one at the same time (flat door panels)

#14

just did some test pieces on various lay ups… the inlet hose i used was WAY too big and went WAY too fast. had tons of air bubbles and then spilled the resin on my favorite pair of jeans. then cut my hand on the CF when taking the peel ply off… hahah what a huge fail.

#15

wow very cool man!

#16

Thanks!

not much of an update… ran out of body filler so the projects been delayed. finally got some today and back to sanding and filling pin holes and smoothening out! man i hate sanding =(

#17

Plug is done. unfortunately my tooling gelcoat expired? idk. it was brand new, had it for less than 2 years, never opened and it was like hard thick jello… is it normal for tooling gel to expire? i bought gel coat at the same time, un-opened and when i shake it, you still hear the fluids swishing around… what a bummer and another GREAT delay. =(

pics of the plug

#18

Cool project. Looking forward to seeing the final part.

#19

Yeah those chemicals do have a self life. Found out the hard way too.

#20

For future reference it’ll buy you some time if you seal them in a plastic bag of some sort. Or I know someone who stores things in air tight “clothing bags”.