3D printed intake manifolds?

[E30 Wagen]

Has anybody here ever investigated 3D printing intake manifolds, either complete manifolds or itb components? I know everybody wants itbs, but designing and prototyping a variable length intake for m20s and m30s is what I'd be interested in, and I wonder how much of the design could be lifted from the m54 or n52.

[Panici]

I've seen 3D printed ITB velocity stacks before.
Is 3D printed material strong enough and heat tolerant enough to be bolted right onto the head?

[bmwman91]

An intake manifold, specifically, is challenging to print since it needs to be made from a plastic that:
- Is not damaged by gasoline
- Is not damaged by oil
- Will not creep / has a sufficiently high heat deflection temperature such that it maintains dimensional stability at temperatures in excess of 80°C
- Will not experience issues due to thermal expansion coefficient mismatch between itself and an aluminum cylinder head

Basically all of the materials that are used in hobbyist printers are a no-no here (PLA, PETG, ASA, ABS). I do know of some people that have used high quality ABS filament to print stuff that has survived under the hood, but as far as I am aware it is severely degraded by stuff like gasoline. As far as I know, nylons do see use under the hood in production vehicles, but you need a higher end printer to deal with it (or a significantly upgraded hot end & build chamber). Nylons do well against heat, but they have problems with moisture absorption (causing them to swell). Glass or carbon fiber filled filament would probably help a bit with reducing its thermal expansion coefficient in the X & Y directions, but would not help much in the Z print direction.

With that said, just prototyping with ABS would likely be fine since the parts would not be in use for extended periods of time. Lots of people on here and other places have done intake prototyping like that. All of the above assumed that the idea was to print parts and use them long-term.

I too have always thought it would be cool to develop a fully variable length intake system to optimize dynamics at all RPMs. It is a little tricky since RPM spans ~1 order of magnitude, so the intake would conceivably also need to do so, but actual designs out in the world do not seem to try to cover 100% of the range since most people are not super interested in performance below ~2000RPM. Got any concept sketches or anything showing what you are thinking of?

[mikey.antonakakis]

I did that back in college (circa 2009) for Formula SAE. It can be tricky - material choice is important. For our car, we used a CBR600F4i engine, which came with ITBs. I did not want to recreate injector ports and the flange on the 3D printer, and rules dictated a single throttle body upstream of the 20mm intake restrictor, so I cut up the stock throttle bodies and bonded the print to them.

Heat and creep are going to be two of the main challenges with thermoplastics, as well as very strong pressure pulses (and vacuum if you are running a single throttle body). I think a good compromise would be to do what I did - cut up the stock manifold to use the flange and injector ports and fuel rail mounts, and epoxy that to the 3d print. Unless of course you're talking metal 3d printing...

IntakeExploded1 by Mikey Antonakakis, on Flickr

IMG_2254 by Mikey Antonakakis, on Flickr

IMG_2275 by Mikey Antonakakis, on Flickr

[Northern]

Our FSAE team did this for a 2005 CBR600RR powerplant circa 2012.

I believe it was a senior design/capstone project.

Manufacturing was done by Realize Inc. ( https://realizeinc.com/ ) but I don't have specifics on the material.

[redneckvtek]

https://youtu.be/IUp3oCGZOzk

[nando]

A guy here with an S54 swap 3D printed some parts on his engine using carbon fiber filament.

The issue is 3D printing materials that can withstand the heat is a lot more difficult because the plastic melts at a higher temperature, of course..

[E30 Wagen]

Got any concept sketches or anything showing what you are thinking of?

I was picturing an intake design like the m54 and n52 that use disa valves and "simply" applying it to an older engine. I understand the science behind how they work, I've just never had the opportunity to see or handle them in real life so I wouldn't even know where to begin. Making a fully variable intake sounds like a daunting project. My brother has been talking about doing the 3 stage manifold swap on his n52, which is what spurred the idea in my head as I was reminded that for the past ~30 years BMW have been making their intakes out of plastic. I have zero experience with 3d printing so I guess it's a bummer to learn that the materials available to hobbyists aren't up to job, though the carbon fiber filament sounds interesting.

M30s, particularly when swapped into e30s, have been taking up a lot of space in my brain lately, so given the chance that's the engine I'd love to experiment with.

[digger]

i have used and will be using 3D printed stacks made from "plastic".

The issue is getting the glass transition temp or heat distortion temp high enough for under hood temps (not too difficult these days from a professional service as they have a wide array of materials).

Also getting a good bolted connection that doesnt relax and loosen is difficult without inserts which you wouldnt want much weight hanging off the inserts as how well they integrate into the plastic is not as good as OEM conventional plastic manifold

It also needs to be done professionally IMO the homemade printers were relatively rubbish when i had it done by a mate. Materials from places like shapeways are very good

i'd limit it to anything such as lightweight velocity stacks anything more than that is likely to be good for a few tests but wont cop the abuse long term IMO unless you have alot of experience

[Northern]

Consumer RP parts vary wildly from person to person. Someone invested in printing can turn out beautiful parts, whereas I can't even get certain materials to print.

Examples being my semi-garbage PETG prints vs ba114 's CF Nylon stuff.

[e30davie]

3d printing has been hallowed as this revolutionary manufacturing tech but arguably it is still in the "prototype only" phase for anything remotely useful.

Unless of course you have $100k+ for one of these bad boys, https://markforged.com/3d-printers/metal-x

I have a cheap 3d printer that I've used to make trinkets and stuff for other hobbies (remote controlled, drones etc) but the things ive attempted to make for automotive just never looked good enough to be considered OEM quality.

[lukeADE335i]

At my work we have a large industrial 3D printer that does titanium printing etc (cost over $3m), that can print a titanium bike frame in 11 mins. It is used for medical prototyping & manufacturing research.

I'd hate to think how much printing a DISA inlet manifold in titanium would cost?!

[JehTehsus]

I think I would not 3d print (assuming <10k$ printer) an intake manifold out of anything except maybe the high temp engineering thermoplastics - and even then I would not expect it to last forever. You are still going to need to do a lot of work finishing the manifold as well. 3D printed parts can be useful in the engine bay for some things, especially stuff that stays below that 80C part, if printed out of ABS, nylon or polycarbonate. I have a coil pack mount that has held up great in the battery tray, for example. As another example, I tried mounting my brake fluid reservoir to an ABS bracket - plenty strong.... until brake fluid touches it and it cracks like nothing.

[TobyB]

I've done a few small things in nylon-
it works.

I wouldn't hang a carburettor off of it, but for spacers, adaptors, and critically,
for prototyping, it's good.
Often, a lathe and a mill's far better.

I can't imagine the work it'd take to design and print an E46 intake.
Probably about as much work as it took to make the moulds for the E46 intake...

My solution was to use an E46 intake- and the head, block, crank and pistons, too.
Not quite bolt- in, but took less time than designing an intake!

t

[varg]

Lost PLA casting. You can also 3D print bucks for mold making or even molds depending on the geometry and use them to form Carbon Fiber fairly easily. FDM is borderline useless for any direct use parts in an engine bay except in specific low load use cases and with limited materials.

Consumer RP parts vary wildly from person to person. Someone invested in printing can turn out beautiful parts, whereas I can't even get certain materials to print.

Examples being my semi-garbage PETG prints vs ba114 's CF Nylon stuff.

PETG is a semi-garbage material to print with lol

You can print with Nylon... Build a drybox, get an all metal hotend and hardened steel nozzle, put the printer in a cabinet. The only reason I don't print with Nylon instead of PETG is that I don't really need the durability and heat handling. I print some interior parts, little brackets, RC airplane and drone parts. PETG is stringy and prone to oozing and blobs but it's fine for most of what I do. I use PLA when I can because PETG is a pain to print. Recently I printed a ring squaring tool and a ring grinder attachment for my dremel in PETG. They came out a bit hairy.