Intake Plenum Material - plastic??

[Baz]

Out of curiosity, does/have any teams ran a rapid prototyped ABS plastic plenum? I recall someone talking about that a while back, but a search turned up no results... I am curious if plastic (say 0.25 inches thick) can hold up to the plenum pressures in a n/a f4i application.

Thanks!

[Baz]

Out of curiosity, does/have any teams ran a rapid prototyped ABS plastic plenum? I recall someone talking about that a while back, but a search turned up no results... I am curious if plastic (say 0.25 inches thick) can hold up to the plenum pressures in a n/a f4i application.

Thanks!

[The AFX Master]

We did a RP intake in 2008, the material is well suited to build an intake (though expensive) and can manage full vacuum and typical backfires at that thickness. One of the main issues that we encountered was the ABS plastic getting attacked (and chew up) by gasoline, so i think you'll need to provide some sort of aluminum lining to avoid gasoline contact at the intake runners. Another potential problem could arise from the "directionality" of the material.. Although advertised mechanical properties of a test specimen tend to be isotropic, parts tend to be a bit weaker in directions perpendicular to the "injection" path that the RP machine followed.. If you do have brackets of some sort they can break fairly easily in stress raisers helped by such directionality.

And if you secure your fuel rail to your intake... you'll get some BIG problems if one of those fails at track.

Regards

[Baz]

Thanks for the input and information - I misspoke in my first post... I would be constructing the runners out of aluminum still, and RP'ing just the plenum.

Rapid prototyping just the plenum should solve the problem of gasoline contact at the intake ports/runners too.

[TimR]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">hanks for the input and information - I misspoke in my first post... I would be constructing the runners out of aluminum still, and RP'ing just th </div></BLOCKQUOTE>

You'll probably still get some gasoline residue in the plenum, especially due to backfires and cranking it over lots. Plus you don't want to exclude the possibility of using aerostart http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Baz]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TimR:
Plus you don't want to exclude the possibility of using aerostart http://fsae.com/groupee_common/emoticons/icon_smile.gif </div></BLOCKQUOTE>

Good point! http://fsae.com/groupee_common/emoticons/icon_smile.gif

[TorqueWrench]

I was going to point out that you still get gasoline vapors in the plenum even if you don't run injectors in them. Pressure waves in the intake, especially if you are running batch fire, can bring a surprising amount of fumes from as far as the cylinder back up to the plenum. Is it enough to make an RP plenum a concern, I don't know and its up to each team to make an engineering decision.

If you don't think I am right as to the amount of stuff that finds its way back, find an old plenum and cut it in half. You would be amazed what you would find...

[jrickert]

Many teams have done RP intakes successfully.

The CNC hot glue gun on crack ABS 3d printers i have dealt with leave an extremely porous finished piece. You can resin and dip the piece in solvent to fix this.

[Muad'Dib]

We tried this last year on our dimension elite 3d printer and it didn't work out so well. We tried to 3d print the entire intake but after we had it on the car we kept getting cracking around the injectors from the vibrations.

[DonMolina]

Too expensive to 3D print the whole thing. It was actually cheaper for us to 3D print a mold with LOM and then CF the whole thing up.

We also kept the original throttle bodies (without the valves) and used them as a part of the runners and as a perfect base for the fuel rail.

[AndrewUofL]

University of Louisville has use a SLS RP plenum and fuel injector bungs and have had great success. We do get the prototyping donated so it helps on the money side of using SLS. Just make sure the thickness is sufficient to support the pressures of a backfire. 0.250 inches should do fine and actually ours is a lot thinner but there was a team at VIR this past spring that had their RP intake explode because it was too thin.

[jdstuff]

I will second the SLS. Many RP shops that do SLS can also apply a cyanoacrylate coating to the part. This material combination is very chemical resistant, and has no problem standing up to automotive fuels.

[Baz]

Thanks for the input all - so it sounds like the laser sintering is the best way to go...

Unfortunately our school only has a RP machine to work with ABS plastic...

But I guess I will see what I can find out about applying a coating to just the ABS plastic such as the cyanoacrylate/superglue that Jason mentioned.

[Mikey Antonakakis]

Anyone care to share the names of some of the more generous RP companies?

[mech5107]

We had build a full rp intake, from throtle flange to runner.

It worked well, but didn't last long. It blew up from a big backfire. The whole thing costs about €900.

There are many companies.
http://www.materialise.com
www.moldkar.com (http://www.moldkar.com)
http://www.mtt-group.com/
http://www.star-prototype-china.com/

[Wesley]

I think Ontario had a RP intake. Backfire blew it up in Virginia '09. Pretty spectacular.

And yeah, low speed reversion plus sitting after a hard run can soak the whole plenum in a film of gasoline.

[kapps]

I'll agree with the fuel in plenum as well. We did lots of dyno tuning last year which involved varying runner lengths between runs and taking the plenum apart. Every time, there was a strong smell of fuel. Last year, our plenum was fiberglass and didn't have problems (restrictor from SLA). This year, I'm planning on a different technique and material for the plenum which will require some fuel resistant coating.

[Apurva]

We are getting our intake manifold rapid prototyped this year... the material that we have chosen for SLS is Duraform-AF (or Duraform-GN (30%glass filled nylon) depending on availability)... has anybody used this material before? ..we've taken the thickness of the plenum as 6mm... the engine that we use is a n/a Honda CBR 600 RR... would it be strong enough to take the stresses due to the pressure differences? i am not sure about the fire resistance of this material... i just dont want this to blow off due to a backfire... could anyone please help?

here is the datasheet for Duraform-AF
www.bastech.com/pdfs/dataSheet_DuraForm_AF.pdf (http://www.bastech.com/pdfs/dataSheet_DuraForm_AF.pdf)

thanks

[Chris Lane]

Last year we rapid prototyped a mould for our plenum, filled it with wax, laid heaps of carbon fibre over the wax, then melted the wax away in the oven. Worked awesome.

[Bazanaius]

Without wanting to divert this OT, that sounds like a pretty similar solution to the one we came up with when we blew up our plenum in silverstone!

Had an RP intake from runners to throttle body - was gorgeous, and worked a treat under suction, unfortunately not so good under a backfire - went bang at Silverstone. Luckily it was just the plenum itself that went, so our runners and nozzle were ok. We cut a sheet of 2.5mm steel, bent it into a toblerone shape and welded on some ends. JB welded the runners and nozzle in place, then wrapped the whole thing in as much GFRP as we could lay our hands on. Worked a treat, and I'm pretty sure it was bomb proof - I dropped it and it dented the floor at one point!

Great fun. Following that we RP'd a second intake (got it within 5 days of blowing up the 1st one!) with a blow off valve - worked a treat.

Major design faults with second one (in hindsight, as always) were:

- Second plenum was made in one piece - made it a bitch to get all the powder out that was left over from the sintering. Caused serious issues with the engine :-(

- Our runners double backed on themselves (like a u) for packaging. Worked well, but as described above it liked to collect fuel. Was fine for the short time we ran, but would certainly need more work for a long term solution.