Why can't an inlet manifold be made from glass fibre?

I can think of 2 reasons:
a) temperature - but CF disc brake run up to red heat so there has to be high temperature resin?

b) reistance to petrol - not sure about this but again there may be some resin/coating that could be used on the internals.

Or some other reason?

Anyone tried this?

yes , most bmw run(race series i cant think of) with a composite intake , ive even made a few .

hmmm, interesting - you say composite - what are the ingredients?

Do you have any photos/more info?

So why are people paying £ 200 for TIG welded aluminium manifold when they could make one from toilet rolls and some GRP?

Surely that is the locost way and you can curve the tracts for better flow, am i missing somehting..?

obvioulsy the male mould need to come out but that could be made up with wax or other material that can be melted out/dissolved at low termperature.

I hope CF is ok !!!!

.

Unsure if this is prepreg or not. I know mine came from Act Performance

PS it copes well with V8 heatsoak very well.

PPS Yes I work in a mess

HTH regards

Agriv8

there are a few problems to overcome. First is vacuum, it needs to withstand the vacuum generated when you let go of the throttle, so bodies close and piston speed high means high vacuum

Second is to make the mating surface to the enngine head airtight. GRP tends to distord under temperature and after it's released from the mould. Need some rubber type gasket and even then it's a pain to make it shut.

3rd You can't use carbon fibre for it as most heads nowadays are alloy and those 2 don't mix!

And I think because of these problems a GRP manifold turns out to be more expensive then a 1 hour aluminium jobbie

quote:

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Originally posted by Agriv8
I hope CF is ok !!!!

Agriv8

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I think I saw some Titanium fibre/resin inlet manifolds on Martin Bell's BMW (BTCC).
Not exacltly locost though!

Why do you say carbon and alloy can't be used together? You would just need to insulate the carbon with a thin layer of glass.

You could definately make a composite intake. You need to pick a high temp and chemically resistant resin. The warping issue could be minimised by good design and processing. The really tricky bit comes with getting a good finish inside and out -not really a project for a garage build!

Oh, and the reason carbon brakes can take such high temperatures, is because they tend to be made from 'carbon/carbon' composites. This is a specialiost composite that uses very high temperature gases over the top of a stack of materials (the preform). As the hot gases touch the carbon, they depoit themselves on the carbon as solid material. This forms the basic carbon-carbon composite. The trick is to then also include materials that restict the oxidation of the material at very high temperatures. This is where silicon-carbide or boron-carbide are introduced, to delay the oxidation proces until very high temperatures.

[Edited on 12/11/07 by twybrow]

I've just got a st170 manifold, it's definately a composite material.



zetec throttle

The upsides are it's light and easy to work, haven't found any downsides. i'll let you know if any arise.

ATB Dan.

www.absmotorsport.net

Several modern car engines use plastic manifolds, the small petrol VAG engines and Rover K series spring to mind.

Production parts tend to be thermoplastics. Generally, they are able to withstand much higher temperatures and are cheaper and quicker to process in large volumes.

They also need to be able to withstand a backfire - ie explosion - inside of them without exploding sending shrapnel into your face.

I did some backfire tests on plastic manifolds a few years ago. Basically we filled the manifold with oxygen and propane I think it was and stood well back before setting it off. Most of the site at work (think airfield size) heard the tests happen.

... and did they withstand the back fire?

Now that is a job I want! Destructive testing by explosion! Sounds good.

Peugeot late s16 engines, and late 1.9 8v engines had plastic manifolds.

I think they were made from glass filled nylon. But you can also add talc, not bath talc to poly prop to make it resist higher temperatures. I used to work at a plastic injection moulding company!

I've been making carbon composite intakes since 1989. Yes, that long ago.

Getting the head seal is no problem, and a good gasket solves the isolation problems.

The prepreg is high temp cure, and then post cure to bring it's Tg point (from hard to putty) up to over 200c. Glass will do the job, and I use it regularly on budget and non cosmetic items. The main thing is to get the right resin system.

It can be done, has been done, and will continue to be done. Just don't listen to the 'can't do' people, and find out how you 'can do'. That's how I work, anyway.

I'll get carbon throttle body/intakes going soon as single entities. Just put as many together as you want and need. Time is all I need.

Cheers,
Syd.

i realise that modern cars e.g. zetec have non-matel manifold - nylon/plastic whatever but I am propose to use GRP - olyester resing and glass matt so is that gonna be that same?

surely if the manifold is made tick enough 1 cm? then is should resist explosions?

There's no poly resin that I know of that will do the job safely. The best is Scott-Bader 272, and that has a Tg of only 85c at best, and that's with post cure.

Cheers,
Syd.

Didn't say it can't be done just pointing out something that needs to be thought about.
I think they all did survive the explosion - i can't remember too much about the test setup to be honest. Although the manifold was in a metal cage with thick polycarbonate screens.

I think it was probably bolted down to a flat piece of steel with fuel rail, injectors and throttle body all attached then filled with the gas through valves in the steel plate.

Syd - I think the point some of us were making was that it would need a lot of thought as it was not really a suitable process for a novice laminator to attempt, nor is GRP really the right material to do it with. Your first line 'I've been making carbon composite intakes since 1989.' Well by the sounds of it, 02GF74 hasn't!

There are resins that will allow temperatures over 200C (Crestapol from Scott Bader for example), but you would be better off using an epoxy based system (probably prepreg based as you say).

If I'm having to use a 'wet layup' system, then I normally use tooling resin (epoxy). This is easily procured from most of the composites materials resellers.

Even a novice should be able to achieve fair results, using vacuum. All depends on how the tooling is made. That is where the time and experience and skill comes in.

Have a go. The worst can happen is it's a balls up. Then you can have another go. That's half the fun!

Cheers,
Syd.

the part i linked is actually a BMW one made from polyester resin , used on quite a lot of race cars .

its only carbon layup to look nice .

we made some GRP flanges aswell .

you could use the original flange , cut the tubes off after the injectors and have em machined so the grp fits snugly inside and use a high temp epoxy glue , quite simple really .

jenvey ram pipes are glued into ally flanges .

True true. Learning is half the fun!

Buy some cheapo polyester laminating resin, get yourself some glass and make some bits and pieces. Its useful stuff to have around anyway for repairs to other items.

Syd - I think the worse that happens could be a rather large (and noxious) exotherm based fire!

Stuff i made .LOL about 7/8 years ago

[Edited on 12/11/07 by Volvorsport]

more stuff

more stuff

hmm, some nicework there volvosport.

could you write a few words on how you made these?

basically what materials - filler/resin did you use? the CF one, hand lay up or use of vacuum former? flanges - does the manifold continue inside the flange hole or butts up to its face? thickness of flange? any reason why flange cannot be made from GF?

I am not looking for bling just functionaility and cheapness so would be using glass matt, making a 2 formers to make 4 inlets then joining onto 2 flanges.

std layup in polyester resin , the carbon was also hand layup .

theres a guy drag racing a turbo bike engine with theses apparently , not sure how he got on with them .

i glued the carbon intakes to the ally using a high temp epoxy cure .

they got tested on QED dyno , moved the power band upwards, theres some sort of variable reflection going on due too the curve of the intake .