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Plastic plenum chambers
BenB - 3/8/08 at 11:33 AM

Is there any reason why people often make aftermarket plenums out of aliminium?? I would have though a plastic plenum could be made and (not having access to TIG) epoxied up much easier than an ali one. And (bearing in mind I know jack sh!t about most things technical) I would have thought plastic would insulate the intake charge better than aliminium from under bonnet temperatures....

Obviously the bit which attaches onto the engine would have to be made from something heat proof due to heat soak.....

Just wondering....


scootz - 3/8/08 at 05:15 PM

I was wondering about this too Ben... obviously, with an RS4 engine running Busa throttle bodies, I'm not going to find something 'of the shelf'!


BenB - 3/8/08 at 05:24 PM

Well I'm going to make a log style plenum chamber out of 4" soil + waste uPVC pipe (well it is a log ) with solvent end caps etc etc. If it weighs half a tonne (or melts) I'll make it out of ali MIG tack weld it and take it to my brother to TIG up properly...


mark chandler - 3/8/08 at 05:41 PM

Jauguar won awards when the new v8 engine came out in 1996 for the use of plastic's.

Inlet, plenum, rocker covers, timing covers plug covers, a whole host of bits and bobs out of plastic.

Lots of production cars use plastic inlets etc so why not.

The hard bit is screwing it all together.

regards Mark


BenB - 3/8/08 at 05:45 PM

Solvent glue for uPVC and epoxy is my plan


RK - 3/8/08 at 05:49 PM

Heat? CF won't be as affected that's why I thought that was used a lot.


mr henderson - 3/8/08 at 05:58 PM

Epoxy pre-preg might be the stuff to use for this application, no heat worries and no adhesion worries

John


martyn_16v - 3/8/08 at 07:26 PM

I'd hazard a guess that it's all about the bling. Much easier to sell shiny metal things for extortionate prices to chavs


BenB - 3/8/08 at 09:14 PM

quote:
Originally posted by mr henderson
Epoxy pre-preg might be the stuff to use for this application, no heat worries and no adhesion worries

John


Yup. But for the hassle and cost you may as well TIG it up with ali!!!!


nz_climber - 4/8/08 at 04:28 AM

My toyota beams 3sge has a alloy plenum, but also has plastic insulators between it and the block, to help prevent heat soak from the block. So there is plastic that handles the heat just fine.


saigonij - 4/8/08 at 07:18 AM

my zetec uses a plastic inlet manifold.


BenB - 4/8/08 at 09:18 AM

Good! I'm going to make it out of plastic and spray it bling chrome to try and prevent heat getting into it....
Good point re plastic insulators- the ST has got them at the moment Not sure they'll cope with boost though so think they're going into the bin probably to be replaced with some silicon tube as a connector between the engine and the airbox...


Syd Bridge - 4/8/08 at 09:49 AM

I've been making cfrp intakes for yank v8's since 1989, when everyone said they wouldn't work!

Currently about to do a manifold to adapt bike tb's to a Suzuki car engine.

Not too difficult to make yourself if you can work with epoxy. You don't have to use carbon, glass will do, even csm.

Just make sure you get the right resin! They actually DO get warm enough to change shape!

Cheers,
Syd.


MikeRJ - 4/8/08 at 12:16 PM

PVC used for drain pipes etc. gets soft at very low temperatures, even boiling water is enough to make them distort.


whitestu - 5/8/08 at 08:29 PM

quote:

PVC used for drain pipes etc. gets soft at very low temperatures, even boiling water is enough to make them distort.



I'm surprised at the - had a go at making an airbox out of black poly downpipe and struggled to get it to change shape using a heat gun.

Stu


mr henderson - 5/8/08 at 08:37 PM

quote:
Originally posted by whitestu
quote:

PVC used for drain pipes etc. gets soft at very low temperatures, even boiling water is enough to make them distort.



I'm surprised at the - had a go at making an airbox out of black poly downpipe and struggled to get it to change shape using a heat gun.

Stu


The black stuff is probably ABS

John