posted on October 07, 2010 21:00
After a reasonably-thorough review of our options, Alex decided he'd try to make new air horns with a little more bend to them. Taking two of the stock rubber air horns, he poured plaster molds that he then sanded, and filed, and puttied, and sanded some more until they were a more appropriate shape.
Next, Alex slathered the plugs in mold release wax, slid a carbon fiber sock over it, slathered it in resin, and used a roll of that fancy plastic shipping stetch wrap stuff to hold it tight while it cured. Afterward, the plaster had to be chipped out.
Not half bad for a first try.
The long horn sits nearly an inch lower than the original, without a significant change in length.
The outer horns now have enough of a bend to pull them away from the roof of the plenum that was shrouding them in our first prototype.
With the basic shape approved, the next step was to make a tool so we could make a few more of them. Making each plaster plug ruins one factory rubber horn, and each plaster plug can only be used once. The first step toward mass production was to ruin one of my funnels. After bending the funnel with a heat gun, it could serve as a solid plug in the middle of what would eventually be a silicone mold.
Sealing the carbon horn with tape, a cupfull of liquidy silicone goo makes up the gap between funnel and trumpet.
The new silicone mold can be removed from the cured horn by first slipping out the funnel, then squishing out the silicone, which instantly springs back into shape.
Now, about that stretch wrap stuff Alex used on the first horns... Though it did a good job of holding the carbon tight against the plaster plug while the resin cured, the wrap is wrinkly, which leaves wrinkles in the surface of the horn. Not cool. We needed something cylindrical and stretchy that could hold the carbon tight against the silicone plug without unsightly wrinkles. Alex had an idea...
Thursday, October 07, 2010 10:05 PM
That is amazing work.
Thursday, October 07, 2010 10:19 PM
Ghetto Fab at its finest!
Thursday, October 07, 2010 10:56 PM
Where can we buy the carbon fiber fabric material and resins to attempt some of this awesomeness?
Friday, October 08, 2010 1:33 AM
Carbon fiber sheets and materials are available thru TAP Plastic. (along with Epoxy/ Resin, hardening). Pretty much everything you need to make whatever piece you want.
Friday, October 08, 2010 6:20 AM
Okay, so where might one find a source for quality pre-impregnated carbon fiber and honeycomb? I've seen ACP Composites as well, but as far as I can tell they seem to offer everything (including standard aramid honeycomb core material, resin, vacuum bags/bag-related accessories, etc.) BUT pre-impregnated carbon fiber. Standard, non resin-infused carbon fiber is fine and all for air horns and other non-structural/small items, but if I'm going to go to the length of honestly making my own carbon fiber parts for strength/light weight, I'd like to have the option of having proper "dry" carbon parts (assuming I can find an autoclave that I can use, of course :P) when I'm done.
Friday, October 08, 2010 8:08 AM
Amazing work again! But just one question would it no hav been easier to just add a speed lump to the hood aka Turbo bump like on the Talon's? Because if it was me I would have even gone to the lengths of buying a cheap plastic fake hood intake expoyied it on then cut the hood to clear the box. But maybe I am crazy lol.... Plus I dont have those mad skills to pull of a job like that! Tried to make a fibreglass box once and its now a really big paper weight somewhere and havent ventured much into its since.
Friday, October 08, 2010 8:51 AM
I read this whole thing slack jawed. Who says small business doesn't work? You guys hiring for a summer internship? All I need is a floor and some decent pay and I can be there in June.
Friday, October 08, 2010 9:18 AM
@ Scott Helmer
What are you making? Prepreg is not necessarily stronger than vacuum bagging or even wet lay up. While it ensures the correct resin ratio that's not that key if you are not making an airplane wing part or something like that. I think you could make any carbon part one would want on a car with regular wet layup or vacuum bagging. Condom bagging has it's obvious limitations but with the advent of the "Magnum" and "RoughRider" that technique has room for growth too.
Friday, October 08, 2010 10:00 AM
you also have to realize that pre-preg carbon has to be kept at around 2 degrees Fahrenheit and also has to be baked at (i believe) around 400f, but i could be wrong on the exact temperature. aside from those 2 things, prepreg is much easier to work with. it doesnt fray as much, you donthave to work with sticky liquids that get everywhere, etc. for just a few DIY things though, dont look at pre-preg as the "right" way to do it. the grams of weight you'll save isnt worth the extra cost.
Friday, October 08, 2010 3:02 PM
Like SteelbluesleepR said, pre-preg is kept in cold-cells at about 2 degree celsious (prior the usage).
Pre-preg is stronger than vacuuming. Vacuuming process just makes sure there are no bubbles/ voids in between the fibers, whereas pre-preg has the exact amount of hardening in it, evenly distributed.
For little carbon fiber projects I generally use Baltek core. It's cheap, easily attainable and strong.
Friday, October 08, 2010 4:50 PM
what a tease!! how can you just stop in the middle like that?!
Friday, October 08, 2010 5:14 PM
If you want to look at it in realistic terms, on a part like the intake manifold, the resin add up to only a couple of ounces, so the weight savings is negligible, but the cost is high. And making your own honeycombed parts is just asking for trouble. Get an air gap between the honeycomb and the carbon sheeting and the part will just tear itself to bits as it becomes stressed.
Friday, October 08, 2010 5:37 PM
Whoah, whoah, whoah. Nobody ever said anything about using pre-preg with the vacuum process. I know exactly how one creates carbon fiber parts, and like I said, I wouldn't even dream of making a dry carbon part without access to an autoclave (I guess I should have also mentioned access to a cold/dry enough area to store it in). Either way, who ever said that I was intending to make a part any time soon? Being recently unemployed, I barely have the money to buy aftermarket parts, much less pay the tooling costs, rent an autoclave, and likely redo the entire process at least once due to an unforeseen manufacturing error. I was just asking as at some point (probably within the next 5 years, after I hopefully get the lucrative position of being a Journeyman worker for my local utilities company), I will most likely be doing a few things involving carbon fiber. The areas in which I intend to use carbon fiber are primarily structural, and as such it is imperative that I use as little as possible (s@#$'s expensive), while maintaining an ideal ratio of resin to fiber, for strength's sake (more/less resin than is ideal results in a weaker part, end of story). On top of that, for the cars that I have right now, I'd like to at least look into making body panels that fit my needs without having to go fiberglass, or have them custom made, or buy either Seibon or VIS or whatever parts. I don't know about you, but I don't know that many people with 1UZ-powered AE86's or EZ30R-powered first generation Impreza's. Those are the two cars I have, and I'd like to have all my ducks in a row before I go ahead and spend thousands of dollars building them (the Impreza, a 2.5RS coupe, is currently bone stock. The AE86 is non-running), all right?
Jesus Christ, is it so hard to answer a question without assuming that the person asking has no idea what they're talking about?
JDMized: I'll look into the Baltek core when I get a little closer to actually making parts. I suspect that it'll come in quite handy in creating a clean, usable dash for the AE86 (my interior is f'ed, and I'd rather just make a simple, usable dash out of wet layup CF than try to find another one) without necessarily killing my wallet. I won't be needing to do so with the Impreza, as I intend to use an '06 STi dash/center console for it, as it will spend most of its life as a street car.
Either way, anything else on this subject should probably be put in the forums. I'm sure somebody on this site would appreciate a good write-up on the different weaves, weights, processes and materials involved in making carbon fiber parts. I still have to study up on which direction the standard 2x2 weave is meant to impart strength, for example. Hell, I wouldn't mind a set of parameters to put into AutoDesk Inventor for FEA analysis, as I'll probably go that route for a certain other project that I have in mind :P
Friday, October 08, 2010 8:18 PM
Jesus Christ? When did he post?
Friday, October 08, 2010 9:28 PM
Eh, last Christmas or so I think. Something about how he was having troubles with his girlfriend. Couldn't bring her to climax more than once, or something like that.
At least that's what I thought he was talking about?
By the way, I can't believe I forgot to mention this: keep up the great work Dave! I can't wait to see the Miatabusa finished.
Saturday, October 09, 2010 11:48 AM
Is there going to be any more on this? I would really like to see how the runners are bonded with the plenum and the intake pipe/filter.
Saturday, October 09, 2010 11:58 AM
Oh there will be more. I am filling and sanding the foam plug as we speak. The runners will be bonded into the box with resin and cloth. They will be part of the box and it all should be very sturdy. I am using 400 deg. F safe resin too.
Sunday, October 10, 2010 2:54 AM
Awesome! I can't wait!
Sunday, October 17, 2010 8:49 PM
To the guy that said you have to autoclave pre-preg. That's not true at all, there are literally tons of dry carbon that is made for oven applications. Also, cure temps and times vary for different resins. Most of the time the temp varies for the part as it is cooked.
Tuesday, October 19, 2010 1:40 PM
Nice work, Dave. Pragmatic, common sense, and smart. Looking forward to seeing more of this.
Wednesday, October 20, 2010 8:28 PM
Just as a comment from a Hayabusa guy, it is a very common mod for us to replace those longer center "velocity stacks" from within the airbox with another set of the outers (the shorter) runners. This from most dyno estimates seems to move the torque and horsepower curves up the rev range, which may be counter productive for your purposes and desires for torque, but would be an ultimately even more simplistic solution to your issue. Just my $.02.
Saturday, January 15, 2011 10:27 PM
Just have to say this was a great article- a welcome departure from much of this site's other content that could better be titled "How to Buy Parts From Our Sponsors and Bolt Them Onto Your Car." That's probably a bit harsh, but it seems like tech discussion in most automotive media today more closely resembles those full page "articles" in newspapers that have the tiny print at the bottom stating that it's actually an advertisement being passed off as an article. Unless you're trying to sell condoms. Then forget everything I just said.
Actually, the condom idea was especially genius. I've had to make silicone couplers for weird bends before using FG tape and the condom idea would have made them come out much prettier and been much easier to work with. I may have to do a 'rough rider' coupler one day in honor of this.
Sunday, January 16, 2011 2:44 AM
Good point kgx I agree, maybe not in the same words, but all in all a good point. It is nice to see some more advanced mods than bolt ons. There are all kinds of grades of readers I would imagine. These guys have to try and keep them all coming back and pay the bills that is just good business.
Where is the ending to this? There is a part six about wires already :/
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