RP of plenum

[Rohit_Kumar]

we want to manufacture our plenum using Rapid Prototyping.
we have SLS and polyamide material for manufacturing.
can anyone give me suggestions on RP of plenum regarding what material should be used and what should be the thickness of plenum?
will polyamide be sufficient for plenum?

[Mbirt]

Hey Rohit,

We were very pleased with the flawless performance of our RP intake assembly this past season. It was directly bolted to the cylinder head of a single-cylinder motor (vibration city) and took intake backfires like a champ. Per the sponsor's recommendation, all surfaces were 5 mm thick. This is the polyamide material that was used: http://www.eos.info/en/product...ems/pa-22002201.html (http://www.eos.info/en/products/materials/materials-for-plastic-systems/pa-22002201.html)

[Racer-X]

We SLA our intake. All the walls are about 1/4 inch thick on ours.

[Rohit_Kumar]

should we do epoxy coating of it after RP?

[Jay Lawrence]

Wollongong had troubles with their RP intakes last year due to erosion by fuel and other fluids. I imagine some kind of coating would have stopped this. Anyone else had this kind of problem?

Perhaps it's worth getting a test piece done and seeing how it responds to heat/fluids/etc, especially if you are unfamiliar with the process and/or the manufacturer.

[Mbirt]

Oh yes, it will be one large vacuum leak at the very least if it isn't coated. It might also have fuel/fluid resistance issues depending on the material used. Our sponsor uses a process they call "imprexing" to seal it and provide chemical resistance. I've seen another team with idle vacuum issues related to an uncoated RP intake seal it with just a thorough spray painting of the part's exterior.

[Ben K]

Our team used a (I think) 30% glass filled nylon via selective laser sintering. Worked great and survived quite a few backfires even at just 1/8" thick. It was thin enough that we could see a backfire through the material at night.

I think my team has used it for a few years now without it breaking.

Ben

[Ben K]

Originally posted by Ben K:
Our team used a (I think) 30% glass filled nylon via selective laser sintering. Worked great and survived quite a few backfires even at just 1/8" thick. It was thin enough that we could see a backfire through the material at night.

I think my team has used it for a few years now without it breaking.

Ben

I want to say this is the stuff: http: //production3dprinters .com /sites /production3dprinters .com /files /downloads /DS_DuraForm_GF_US.pdf

[JWard]

I can attest to the strength of RP'd intakes. I think we had a fibre reinforced nylon (Don't quote me on that), through which you could see back fires. The plenum chamber you could also see flex during transitions between Close and WOT. I mention this, because I also remember the backfiring events when we got a bad sync (wasted spark starting), you could see the combustion events in the intake. I think the material was better than other RP materials because it had this flex to absorb such events. (For instance I know the wall thickness on a previous intake when using alumide(spelling?) was greater than when we switched to the nylon. Thus ssaved a fair amount of weight)

(Go view warwick racing website / fbook for pictures of the WR1 plenum - the monster green colored one)

[Nicky]

Out of curiosity, has anybody tried printing their own intake?? Using something like the makerbot??
MakerBot Replicator 2 (http://www.youtube.com/watch?v=uQWxFlQWLcU)

I have a bunch of questions that follow this:
Would the intake last backfires?
Would additional coating be required??
Is it technically possible to make reliable non-critical components for FSAE out of cheap printers like these?
Does anybody know somebody with such equipment? Can you try printing out something like this?

Regards,
Nikhil

[JWard]

I forgot to mention. We used Dictol (again spelling?) to seal our intake.

[Cardriverx]

We have had some great and horrible experiences with RPed intakes. First the bad:

Make extra extra sure the wall thickness is sufficient. The vacuum that an engine pulls plus the surface area of a plenum really can create a lot of force. This can cause flexing (or failure!) which is something you don't want, you have now just created a variable intake plenum that also affects airflow when it flexes... not good. You can use shapes to counteract this too, for example a spherical plenum is inherently stronger. And yes I have caused a RP intake to implode on the dyno... This goes for fuel rail brackets too (fuel pressure plus injector pintle surface area can really bend your mounts if they are not designed well, which results in you using zip-ties to hold the injectors in...).

As for materials, we use Realize Inc for our intakes because they are awesome (they send candy with every order, can't beat that). They use SLA, and we specifically use the Accura 60 material. One thing to keep in mind with SLA is that usually the material is cured with UV light. So if you use an un-coated part in the sun it will over cure and get very brittle... don't ask me how I know haha. So make sure to paint it. We have never had any issues with Accura 60 and fuel, it works just fine.

Finally the good. RP just makse it so easy to make an intake with crazy geometry, integrated brackets, etc etc. For that reason alone it is worth it.

Just when in doubt, make it a little thicker. The last thing you want is a broken intake at comp or one that flexes a lot so your tune is extremely hard to dial in.

[Owen Thomas]

Just when in doubt, make it a little thicker. The last thing you want is a broken intake at comp or one that flexes a lot so your tune is extremely hard to dial in.

+1. Our CFRP intake imploded during noise in Lincoln last year. 0/10 would not recommend, add the extra 1mm.

[BluSTi]

Originally posted by Owen Thomas:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Just when in doubt, make it a little thicker. The last thing you want is a broken intake at comp or one that flexes a lot so your tune is extremely hard to dial in.

+1. Our CFRP intake imploded during noise in Lincoln last year. 0/10 would not recommend, add the extra 1mm. </div></BLOCKQUOTE>

I imagine the ingestion of foreign materials didn't bode well for your engine either.

[Mbirt]

Originally posted by Nicky:
Out of curiosity, has anybody tried printing their own intake?? Using something like the makerbot??
MakerBot Replicator 2 (http://www.youtube.com/watch?v=uQWxFlQWLcU)

I have a bunch of questions that follow this:
Would the intake last backfires?
Would additional coating be required??
Is it technically possible to make reliable non-critical components for FSAE out of cheap printers like these?
Does anybody know somebody with such equipment? Can you try printing out something like this?

Regards,
Nikhil Nicky,

You would certainly need to reinforce parts from a MakerBot with glass or carbon fiber. It looks like their machine has come an astonishingly long way, but the build size capacity is small and the materials (PVA and ABS) are certainly in a lower league than the Nylon-like properties of professional-grade machines. I've used a modern "prosumer" desktop-sized machine we have on campus (~10,000 USD) to make a prototype restrictor diffuser and experienced multiple breakages of the part in the short time I tested it. The strength of the part was significantly lower than the intake produced by the same machines and processes used to create prototype intake manifolds for the auto industry.

I would suggest finding a sponsor in North America, Europe, or Asia and dealing with the complications of shipping.

[Cardriverx]

When it happened to me, due to the elasticity of the material when it broke the pieces were much to large to be ingested. The engine actually ran with a 3 inch hole in the plenum until I could figure out what happened!



Originally posted by BluSTi:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Owen Thomas:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Just when in doubt, make it a little thicker. The last thing you want is a broken intake at comp or one that flexes a lot so your tune is extremely hard to dial in.

+1. Our CFRP intake imploded during noise in Lincoln last year. 0/10 would not recommend, add the extra 1mm. </div></BLOCKQUOTE>

I imagine the ingestion of foreign materials didn't bode well for your engine either. </div></BLOCKQUOTE>

[JWard]

I wouldn't say that the variability in the volume due to the flex was appreciable, certainly much less than a % of the total volume of the intake. Also the flex was only under closed throttle, which isn't parituclarly a high priority for tuning the intake volume.

I would agree with Mbirt's comments on the grade / quality of materials of the 'hobbyist' level machine produced parts. Also would agree on the statement about keeping wall thicknesses within spec, don't skimp out. Also, bosses for attaching fuel rails, just overspec them - we were running with ziptied injectors for a short while as well as Cardriverx's team.

[mech5496]

IMO, RP plenums are a total waste of money (that's if you pay for them). We tried using one back in 2010, which exploded into million pieces due to a backfire of our WR450. Our CF one took less time to build (we have neen waiting the rp one for 2-3 weeks), weights a fraction of the RPd, and has lasted many many backfires. It also costed next to nothing...

RP is nice, but not for parts like intakes or fuel tanks. Electronic boxes, swith panels (like thew most awesome switch panel ever on Swanseas car), brake lights, all kind of non structural parts should be neat...

[Mbirt]

Originally posted by mech5496:
IMO, RP plenums are a total waste of money (that's if you pay for them). We tried using one back in 2010, which exploded into million pieces due to a backfire of our WR450. Our CF one took less time to build (we have neen waiting the rp one for 2-3 weeks), weights a fraction of the RPd, and has lasted many many backfires. It also costed next to nothing...

RP is nice, but not for parts like intakes or fuel tanks. Electronic boxes, swith panels (like thew most awesome switch panel ever on Swanseas car), brake lights, all kind of non structural parts should be neat... I agree it's definitely easier to have a rosy outlook on RP parts when you've haven't paid for them. Haha. Can you recall how thick the failed RP plenum was and the process/material used? A quality part from a company like Synergeering in the US might change your opinion about RP intake parts.

[Jon Burford]

Originally posted by mech5496:
Electronic boxes, swith panels (like thew most awesome switch panel ever on Swanseas car), brake lights, all kind of non structural parts should be neat...

I'll pass on your compliments Mech http://fsae.com/groupee_common/emoticons/icon_smile.gif

The swansea plenum was 3mm RP done by CRDM in the UK in about 2 days. We were very pleased with it. It's a bit of a strange shape and we didn't have the time to get it made in carbon.
The plan was to make the RP part thin and then cover it in Carbon to add strength and save weight. this is what we did.
It's 3mm all over, with a single layer of carbon. No issues on the dyno or in the car running our phazer at 12psi of boost and no problems with the temperature either.
we saved a fair amount of weight this way, but I wanted to play it safe. If I was doing it again, I would reduce the wall thickness of the RP and add another layer of carbon.

[mech5496]

Pretty sure it was SLS and I think about 3mm with a spherical plenum, cannot recall the material/manufacturer though. I also remember trying to use the restrictor part which was intact and covering it with CF, but resin refused to adhere with the RP part. Jon, cf covered rp intake is a cool idea for complex interior shapes, but I would still be worried about backfires (huge issue on singles) which could cause the RP inner skin to crack and peel off without any visual signs on the intake itself.

[Jon Burford]

Because of the configuration we used, the throttle was not actually part of the plenum, but yes, I hear you with regards to backfires.
A risk we take I guess. I am not the carbon guy, I don't know how he got the carbon/resins to adhere properly, they really did though. I am confident the 3mm wouldn't have been enough with the carbon.
due to the setup, it's fairly easy to check the inside of ours. I did so after the dyno and then more recently after FSUK. There doesn't seem to be any damage or signs of anything nasty so I guess we got away with it http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Cardriverx]

I think it is more of an advantage for the multi-cylinder cars because the intakes get more and more complex to make. Plus if you have the time to do the simulation, you can really easily make internal vanes/walls/ducts/etc.

It sounds like you didn't use that great of a company either, Realize can get us an intake in about 3 days after sending them a model.

[JWard]

I'm trying to find a picture of your s12 dash Jon, but no luck... Do you have any on your phone or a pointer to one already online (couldn't find any on the website or facebook page?! http://fsae.com/groupee_common/emoticons/icon_confused.gif)

The RP and carbon plenum was something we wanted to do with the wr1, but we decided we knew we wouldn't have the time to lay it up. The bodywork took two of our 12 guys about a week to make the moulds, finish the moulds, lay the carbon and cure, finish the carbon, wrap it etc.

Last years car moved to a fully CF plenum and intake. We had to travel quite far to get access to an area to lay it up though. Our supplier donated bench space, advice on laying up, tools & autoclave, but to use it the two team mates were camping in a scout campsite near the facilities! In our situation an RP intake was available significantly earlier than if we'd involved CF, and in that respect ultimately the best decision.

[Jon Burford]

@Jward.
Hi,

http://i48.tinypic.com/a3102c.jpg
and
http://i50.tinypic.com/1230ah4.jpg
for a close up.
These were made on a HP machine by a company based at our university, not the same technique used to make our plenum.
I hear you with regards to the struggle with the carbon work, which is why we decided to use the SLS to get rid of all the moulding etc, and then just apply the carbon outside to get the strength, all can be done quite easily.

[Dash]

Originally posted by Jon Burford:
@Jward.
Hi,

http://i48.tinypic.com/a3102c.jpg
and
http://i50.tinypic.com/1230ah4.jpg
for a close up.
These were made on a HP machine by a company based at our university, not the same technique used to make our plenum.
I hear you with regards to the struggle with the carbon work, which is why we decided to use the SLS to get rid of all the moulding etc, and then just apply the carbon outside to get the strength, all can be done quite easily.

Jon,

Totally off-topic question but what kind of joint do you have in your steering system? if that's a u-joint it seems like its operating at quite a high angle! just curious!

[Jon Burford]

Originally posted by Dash:
Jon,

Totally off-topic question but what kind of joint do you have in your steering system? if that's a u-joint it seems like its operating at quite a high angle! just curious!

Hi Dash,
it's an angle gearbox. 45deg if memory serves. Just an alternate way of doing it which gets rid of the UJ's. it adds very little weight and we think it feels better than the UJ's we had.