RP of plenum

[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

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

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.