Carbon Fiber!

[nogaro420]

Hey guys,

For next year I am thinking of doing an entire carbon fiber setup for our intake, from the throttle body all the way to the intake runners. I was wandering if anyone has any suggestions on what techniques might make my life easier with this process.

Brian Flynn
U. of Pittsburgh FSAE

[nogaro420]

Hey guys,

For next year I am thinking of doing an entire carbon fiber setup for our intake, from the throttle body all the way to the intake runners. I was wandering if anyone has any suggestions on what techniques might make my life easier with this process.

Brian Flynn
U. of Pittsburgh FSAE

[jack]

why do you want to do that out of carbon? i dont know if you have ever tried, but making lots of organic shapes out of carbon is a royal pain in the ass. your whole intake assebly will probably be dictated more by manufacturablility (word?) rather than how you think it ought to be designed. we tried a carbon intake for our car, it took about 6 molds for a simple log design, and looked like crap when it was finished. if we stuck with it, the amount of time it would of taken to sand down and make pretty would never of been worth the effort.

..but on the other hand, if you pull it off--it would look cool...oh, and i would bladder mold it if you can.

jack @ WWU
http://www.etec.wwu.edu/

[js10coastr]

we did it once...we're using sheet now.

It was extremely difficult, and the weight savings are minimal. But, I believe we used wax molds for most of stuff.

www.calpolysae.org (http://www.calpolysae.org)

[Travis Garrison]

You might look at making styrofoam blanks / forms to layup over...and then using acetone or some other solvent to disolve away form once your part has cured...Not the best method, but quick, relatively easy, and all hand work. You'll probably want to use a layer of bondo on the outside of the styrofoam in order to get a reasonable surface finish (it will have to be chipped away after the foam is removed). Also you'll want to find the highest density foam possible, as light foams won't let you pull any vacuum.

Be careful with lost wax techniques...I've seen it done once and it left wax ALL over the part (in the pores, in addition to a fine surface coating)...making it impossible to ever laminate or bond to the part after the wax had been melted out...

For some shapes you can get away with simply cutting the part off the mold and doing some eyeball alignment to patch the back together later. Sometimes you'll have to cut the mold / form in half as well, then patch it back together for the next part.

I would be carefull with bladder molding, I don't have any experience with it, but wrinkles will almost always show up on the bag side of a layup, and with bladder molding those wrinkles would be on the inside of your runners or plenum rather than the outside...which could make for a great looking part with lousy flow if you aren't careful. I believe this can be avoided easily enough but requires custom cast silicone vacuum bags (somebody correct me here if you know of an easier way).

If you need precision, consider matched dye or molds that can be dissasmbled to get the part off...cnc em out of aluminum and you're golden. Matched dye does require you lock yourself into a laminate thickness though...Or maybe make several molds and laminate the pieces by hand...

You should probably listen to Jack and js110coastr though...if you're trying to save weight you should go for the low hanging fruit first rather than trying to shave ounces off of what should already be a light component of your car.

[EliseS2]

If you are using the lost foam technique and want good surface finish, we found a great technique. We poured some very fine sand into the almost finished intake and taped up the ends. We then put it on a lathe over night at a low rpm. The inside ended up being extremely smooth.

[Travis Garrison]

EliseS2


Thats a pretty damn good idea....a rock tumbler for composite parts....

Travis Garrison
WWU FSAE

[Cody the Genius]

We have made ours out of carbon for a long time and had no real problems with wax. We just use radip prototyping to get the shape and the sand the heck out of it until its silky smooth. Next we just lay-up over it and vacuum bag it. Then all you have to do is borrow someones oven and melt the wax out. Just be careful because the wax is flammable and can cause a big smoky fire if it hits the heat element, found that out the hard way. this has always given us a really smooth interior and although the outside looks a little rough from the vacuum bag you can still sand it or do whatever you want to make it pretty but the motor doesn't care about that.

"GO MOTOR!"

[jcs17]

A good option for building a carbon fiber intake might start with showing up to the shop and doing some work.

[RagingGrandpa]

one hell of a first post!

both of the carbon intakes I've seen built on our team involved at least two weeks worth of really late nights and the builders nearly resorting to violence...

"...with powershifts and tiresmoke for all"

[Michael Jones]

And why carbon? We've done ours with fiberglass for eons now (with a bit extra coverage in problematic spots, like the diffuser to the intake line...) Agreed with previous comments that carbon is a bitch to get around complex curves. Acetone metling I wouldn't recommend unless you have someone with very small hands to sand the inside - you get blue blobs of crap in there.

Inside finish is of course the most important, but don't neglect the outside. Psychologically, if the outside looks like the surface of Mars, then judges might be inclined to think the inside does too. You could prove that by opening it up, sure, but...

---
Michael Jones
Coordinator, Student Project Teams, College of Engineering

Cornell Racing
http://fsae.mae.cornell.edu

[Michael Jones]

And that is a hell of a first post for jcs17. I'm suspecting this is in relation to the initial posters talking but not doing. If so, might I suggest summoning the cajones to address that privately and directly? Not only do we not give a shit, it builds piss-poor organizational morale to engage in such practices. Trust me, my home department does this shit all the time.

---
Michael Jones
Coordinator, Student Project Teams, College of Engineering

Cornell Racing
http://fsae.mae.cornell.edu

[Andy K]

jcs17, you're way out of line to take this on an international stage. If we were to have problems on our team we would take care of it mano-a-mano.

We did ours in CF last year from the turbo to the runners. We had a few probs last year but it did have a silky smooth inside. We're going back to sheet just because we can't physically make our design out of CF. Ok... let me restate that. It's easier to make it out of aluminum sheet.

Andris Kanins
McGill Racing Team
2002/2003 Body Design
2003/2004 Suspension

[Tim B]

Aluminum seems to be the best and most widely used material for the intake. Compare and contrast what you would have to do to fabricate and the difference in weight (if the aluminum intake is done right)between the two and I think the right choice will be obvious. But on the other hand, if you have the time and patience for the carbon fiber, why not go for it and see how it turns out. Then you can see what will work best for your application.

"An expert is someone who knows more and more about less and less, until eventually he knows everything about nothing"