Come right down to it, intake manifold is one of the least complex things I want to cast as functional parts, so might as well take as many tries as necessary to learn to get a good part.

 

i don't know anything about casting, but it seems like engine flange down and its its own riser

 

I did not know you were attempting plaster investment casting.

So, are you printing the pattern to make an investment mold? Internal coring?

 

/Yeah, at this point I'm doing plaster investment casting. I know when/if I get to production I'll have to do sand stuff, if I want to do any sort of volume, but plaster casting takes a lot of tricky bits out at this stage of things. No messing with so many core boxes and binders and stuff, instead I'm directly printing the pattern and burning it out. On the intake manifold, I reckon I can just fill the intake runners with plaster for coring - there's plenty of room to break the plaster out afterwards. Other stuff I have in mind I'll definitely have to get to using sand cores.

I note that I'm really really early on in the process of teaching myself all this crap - I have ideas, ambition, and a homebrew foundry, but experience, well, not so much. Still, I've been wanting to do crap like this for 15 years, so no time like the present to learn.

 

egg-zach-lee, whats the worst that could happen? you melt it down and start over?

 

This is really cool, sub'ed!

In addition, following 3D printing there is a guy who has figured out how to print carbon fibers, as soon as that becomes more mainstream I would love to see intakes made this way.

 

Right, and I have quite a bit of scrap aluminum kicking around too anyway.

 

Just got reminded of this thread. So, progress got stalled a bit by me buying a house and my dad and I building his street NC into an SCCA T4 car. Looking at getting back to it soon though. Also, check this out:



Full size (but not cleaned up) version. I think that including the throttle bodies it's like, 12" from keg to plenum, so should be pretty nicely high-rpm oriented.

 

Mazda's peripheral port race engines use 18" long runners and they shift those engines at 8500 rpm.

 

Depends on the race engine? SAE900032 looks at a bunch of runner lengths, starting from a baseline of 400mm and suggests that 350mm would have a torque peak of about 8500rpm, this measured from the wall of the epitrochoid. I'm also SWAGing on the runner length of my manifold - it's been a few months since I looked at it, and I don't know that I took the time to do a good job measuring runner length at the port centerlines - done that way, it's probably a little longer. It wouldn't surprise me if port face to plenum it's about 15", which would tune for a torque peak around 8k or so.

Yeah, I know, high. Couple things though - there's packaging limitations in the frame it's going into, it's kind of a first cut manufacturing feasibility thing (straight shot is a lot easier to do than a wraparound manifold), coming up with longer air horns is a possibility, and I can always just do another one since the whole thing's in Solidworks and I set up the length to be tunable by moving one reference plane. Besides, it's longer than the old Lake Cities manifolds. Also, I designed it to bolt to an EProd ported shortblock, so maybe it'll be about right.

 

You should have printed two of them. One with "blocks" on the end for the cavity and another with extensions (ID the same as the OD of the "blocks" on the other so you could cut it in half and use as a core box. It would be nice if the core box was metal so you could bake the core in the box but, with care, you can remove the core and bake it by itself.

 

I view it as a "one thing at a time" sort of deal. I did some plaster investments of 3d printed plastic and successfully burned them out - now I'm trying to do a bigger one where I need to do runners and all the rest. Because I'm investing it instead of doing sand, I don't have to worry about core shift or the sand breaking apart or all of that sort of thing yet. I actually haven't done this big of a pour yet before either... there's enough stuff to go wrong as is. Besides, the plastic's pretty cheap. Like I said before, I know I'll have to move up to sand casting at any sort of reasonable production level just... not yet.

Incidentally, not having done work with cores, only research, would something like sodium silicate and CO2 for a core binder work better given as how my pattern won't hold up to much temperature?

 

Ahhh... Investment casting, I forgot you had been heading down that road. Whoever does your machine work will thank you! I've machined too many poor casting full of sand that just destroy cutting tools.

I don't know man, I've seen some pretty big stuff investment cast. Maybe it's the thickness ofthe investment? Are you firing the investment?

As far as core binders go, I don't know what they use. I have limited knowledge in the actual making of the cores but have lot's in using them in permanent molds. In other words, I've been involved in the metal part of a permanent molds and making sure the cores fit right. This is how most modern aluminum intake manifold and cylinder heads are made. The company I worked for did work for a supplier to Toyota.

 

Given as how I'm the guy doing the machine work too, that's perfect. I'm optimistic it will turn out if I do my homework, but I've been holding off until I have a less makeshift crucible. The idea of filling a Goodwill stainless sauce pan most of the way full with molten aluminum is kind of intimidating me.

 

Ya think??

 

The best (worst) part is before the aluminum melts and starts equalizing heat - there's spots that were glowing at least orange, on the (probably) 18 gauge stainless saucepan. I started to think that hey, maybe I've proven this part of the concept and should really invest in doing it the right way before something goes really wrong.

 

i saw one homemade that was great, long rod to get way back from it.. used a square tube to engage the handles on the bucket part.

 

The ones you printed are very similar to the Lake Cities design. Atkins Rotary bought the rights to it and still sells it. The Lake Cities design was known for producing very good power up top.

84-92 Rx7 45mm Throttle Body & Intake Kit...

 

Yeah, in basic layout that was the inspiration - I have an old 12A Lake Cities manifold kicking around. I never liked the way it transitioned to the keg though, and you can see how with the spacing of the snowmobile TBs how the outer ports get straighter shots than the LC one.

 

It's too bad that Atkins casting job is so terrible. I had the DCOE wraparound style and I couldn't even fix the runner openings to match the engine ports no matter what I did. I ended up selling it unused for a fraction of what I paid for it.

 

Well, as a quickie update, finally ordered a real crucible. Should hold something like 15-20 pounds of aluminum at a time... should be enough for my purposes for now. If I get really ambitious about making a transmission casing, well, there's always bigger crucibles.

For bonus points, I'm working through a pile of S4 intake manifolds and FB 4-spoke wheels for a source of aluminum, at least for now.

 

Go hit the yard for Toyota aluminum intake manifolds. I know they are good quality aluminum or, put an add on Craig's List. Be careful of some aluminum wheels, they are die-cast which is not very good aluminum. Same goes with a lot of other aluminum parts on engines like some valve covers, timing covers, t-stat necks. You want aluminum from permanent mold technique and not die-cast.

 

I actually have prototype castings made quite often from a few different suppliers. Low quantity runs though i find these guys below to provide a decent part for not as much as you would think. Have had aluminum, and stainless run through these guys.

http://www.investcastinc.com/

 

I agree and I had the same problem, maybe if I had an REW f/r housings it would fit.

I bought from the a 13b 4 port side draft manifold so I can carb a t2 block and it the holes for the carb were not round, it had a casting hole that would cause a big vac leak and needed to be jb welded. they packed it poorly and the gasket surface got scratched.

I hate atkins I do not trust them or their own parts. I tried to contact them about this and it fell on deaf ears.

you can even see it their EFI kit, it looks sloppy.

 

yeah this outer water seals they make also look a bit sloppy, they look to be cut square form a round seal with a knife. also they do no have this withe side so you dont really know which side to put them/