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GameboyRMH
GameboyRMH PowerDork
1/30/13 9:21 a.m.

I've been thinking about the design of an ITB adapter and it's getting fairly complex and potentially chunky - not large in overall dimensions, but I may have to use some meaty bits of metal, and I want to save weight. Then it hit me, could I get this thing 3D printed in some kind of plastic? I'll have to CAD-design it anyway. First time I'll be using CAD too.

Anyway, does anyone know what kind of plastic the off-the-shelf ones are made of, and how much do they suck?

81cpcamaro
81cpcamaro HalfDork
1/30/13 9:28 a.m.

Of the internet, GM uses Nylon 66. The intakes have proven to be reliable and have been around a while now, so I don't see why it wouldn't work.

GameboyRMH
GameboyRMH PowerDork
1/30/13 9:32 a.m.

Ah excellent. I Googled around but couldn't find what they were made of. It is possible to print in nylon 6/6.

And for those who are going to ask, yes I'm considering CNC'ing and casting too, the advantage of plastic would be the weight savings.

fanfoy
fanfoy Reader
1/30/13 9:36 a.m.

Check out this thread. From FSAE forum.

fanfoy
fanfoy Reader
1/30/13 9:39 a.m.

Unless you absolutely want to go fancy, just get a UHWMPE plant pot, cut and plastic weld it to the desired shape, and put a layer of fiberglass on top to make sure it's air tight.

ransom
ransom SuperDork
1/30/13 9:41 a.m.

I wonder if/when the laser sintering printers will get down to consumer pricing...

Probably better off setting my sights on a Bridgeport...

GameboyRMH
GameboyRMH PowerDork
1/30/13 9:51 a.m.
fanfoy wrote: Unless you absolutely want to go fancy, just get a UHWMPE plant pot, cut and plastic weld it to the desired shape, and put a layer of fiberglass on top to make sure it's air tight.

I don't have much of a choice but to go fancy, the side that connects to the ITBs has to gently flare out at the sides, sort of like the shape of Mega Man's boots. That's the shape of the outlet side of the blacktop ITBs, sort of an oval/diamond shape. The rest of it is fairly simple so I may go with a mix of metal and plastic. It'll be a 2-piece that will need to be sealed with a section of hose & clamps in the middle, this allows me to make it very compact without making assembly and installation impossible. I'll have some threaded rods to hold it together so the hose isn't serving any structural purpose.

So it's looking like Nylon 66 is still the best bet, on that FSAE forum there are complaints about ABS and sintered metal intakes blowing up (blew the prints on your intake!) and being degraded by gasoline.

4cylndrfury
4cylndrfury UltimaDork
1/30/13 10:29 a.m.

I have the equipment at home to melt and cast aluminum...Id be interested in casting these for you if you are able to get me 2 or 3 printed pieces in plastic to use as patterns and cores, with 1.5% overall dimensional enlargement to account for metal shrinkage as it cools from liquid to solid...

Let me know if youre interested.... butlerbmx at Yah00 dot c0m

DILYSI Dave
DILYSI Dave MegaDork
1/30/13 10:55 a.m.

Nylon 66 is good stuff. Unfortunately, it isn't able to be printed at this points.

GameboyRMH
GameboyRMH PowerDork
1/30/13 11:01 a.m.

Is this not the same stuff?

http://www.3ders.org/articles/20120523-3d-printing-using-nylon-to-make-flexible-parts.html

If it can be done with DIY'er-grade equipment I imagine the commercial shops are doing it already.

Kenny_McCormic
Kenny_McCormic HalfDork
1/30/13 11:17 a.m.
81cpcamaro wrote: Of the internet, GM uses Nylon 66. The intakes have proven to be reliable and have been around a while now, so I don't see why it wouldn't work.

Well, if you dont put a liquid cooled EGR passage through it, and never have a backfire, it works great.

fanfoy
fanfoy Reader
1/30/13 11:31 a.m.
GameboyRMH said: I don't have much of a choice but to go fancy, the side that connects to the ITBs has to gently flare out at the sides, sort of like the shape of Mega Man's boots. That's the shape of the outlet side of the blacktop ITBs, sort of an oval/diamond shape.

That's why I suggested a plant pot. Most of them have a flange that flares on top so you can connect it to your ITB. Something like this:

GameboyRMH
GameboyRMH PowerDork
1/30/13 11:37 a.m.

So you're saying I should make something like a box with holes for the ITBs on one side and the engine's intake ports on the other, like that "toblerone" idea in the FSAE thread? I guess it could work, but is that good for performance? My idea would have a tube for each ITB.

unevolved
unevolved Dork
1/30/13 11:47 a.m.

It should be completely possible, if the design's right. I want to see this done, I may have to copy you if it works well.

fanfoy
fanfoy Reader
1/30/13 11:51 a.m.

I thought you wanted to make a homemade/plastic version of something like this:

I think I understand that you would like to have the flare at the end of your ITB to come flush with the base plate? If space is a concern, then yes, you would be better off mounting them flush, if not, just increase the volume of the plenum to slow down the air a bit before it gets sucked in the ITB.

GameboyRMH
GameboyRMH PowerDork
1/30/13 12:09 p.m.

No I'm trying to build an ITB-to-head adapter, similar to this one on SkinnyG's locost:

You can see the ITBs bolt to a flange (separate here, but they could be attached together) and then meet with tubes that lead to the intake ports (looks like they're painted black here) and the connections are sealed with tubing and hose clamps.

The trouble is that the actual outlets on the ITBs I'm using have a complex shape, so for smooth airflow they have to match up. Making that shape and keeping it identical on all 4 is the tricky part.

The airbox is another matter, I was planning a simple box around the trumpets with a lexan side, just for good looks

Edit: Better pic of SkinnyG's setup:

Swank Force One
Swank Force One MegaDork
1/30/13 12:11 p.m.

Find out what material Outlaw Engineering is using for their thermospacers.

GameboyRMH
GameboyRMH PowerDork
1/30/13 12:14 p.m.

Looks like it's this stuff:

https://en.wikipedia.org/wiki/Phenol_formaldehyde_resin

I'll sure look into using it for the replacement intake gasket.

fanfoy
fanfoy Reader
1/30/13 1:15 p.m.

At this point, I'm gonna have to say "we need pictures" because I'm having a hard time visualizing what you are trying to do. Usually, the part between the head and the ITB's is the easy part: A flange with four tubes sticking out and a hose to connect it to the ITB's.

chaparral
chaparral HalfDork
1/30/13 1:28 p.m.

Turn the intake runners on a lathe out of foam. Make the intake manifold shape out of foam. Lay-up the cheapest bidirectional carbon fiber cloth and vinylester resin you can over the foam. Dissolve the foam with acetone or gasoline.

GameboyRMH
GameboyRMH PowerDork
1/30/13 1:34 p.m.
fanfoy wrote: At this point, I'm gonna have to say "we need pictures" because I'm having a hard time visualizing what you are trying to do. Usually, the part between the head and the ITB's is the easy part: A flange with four tubes sticking out and a hose to connect it to the ITB's.

Here's a real quick MS paint sketchup:

Yeah it's normally simple, the interface between the diamond-shaped ITB outlets and the round tubes is the hard part. The sketch isn't to scale and the diamond-shaped outlets are bigger than the engine's intake ports and therefore the runner tubes as well.

Edit: If it's not clear the ITBs I'm using have a built-in mounting flange and I can't just hose-clamp onto them.

fanfoy
fanfoy Reader
1/30/13 2:04 p.m.

Now I get it. Well if your diamond shape is larger than the tube it's going into, it's easy to form the end of a metal tube using a former. It would probably be easier than making a plastic or composite transition and then attaching it to a mounting plate.

This is how I would make it.

1 - Take a piece of steel big enough that you can cut and grind the shape of the diamond outlet. Give it a bit of a wedge. You can do all this manually with a grinder and a lot of patience or if you have the means, have it machined. Don't forget to give it a tapered end small enough that it can fit into the round tube you will be using.

2 - Use your newly formed wedge and form four little lengths of tube by slowly forcing it into the tube using a press or a lot of hammer blows. Preferably anneal to avoid cracks.

3 - Weld your four little transitions to a plate with the shaped cut into.

GameboyRMH
GameboyRMH PowerDork
1/30/13 2:04 p.m.

Here's another idea: If I just oversize the pipe and tell smooth flow to go screw itself, would that be very bad for performance?

fanfoy
fanfoy Reader
1/30/13 2:12 p.m.

Well...it's much simpler, but kinda defeats the purpose of going ITB in the first place.

I gotta ask, what kind of ITB are those? Never seen ones with a diamond shaped outlet.

Also, don't let my description discourage you. It's really quite simple.

GameboyRMH
GameboyRMH PowerDork
1/30/13 2:14 p.m.

4AGE 20v blacktop ITBs.

I like your idea of stretching some tube with some kind of custom form used like an anvil horn, it should give a consistent shape.

My last post wasn't in reply to yours, we posted at almost the exact same time.

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