Plenummmm

[oakey]

Regarding a plenum chamber for my m20 with itbs.
Can anyone make or supply me with something like this for a fairer price?

http://cgi.ebay.co.uk/Turbo-supercharge ... 5188992f0d

Or does that price seem ok for what it is?

[Turbo-Brown]

You not fancy a nice carbon fibre one dude?

[oakey]

You not fancy a nice carbon fibre one dude?

I just figured if I could get one of ^those^ for cheap that fitted it may be an easier option as it would just need 6 correct hoses/pipes a plate welded on and a to match the throttles.
Yes I would love a cf one! I've been messing about a bit today and created a cardboard airbox Couldn't find any foam.
Going to get some foam board over the weekend and carve one using that. Did you know the tb's are the same size as kitchen towel rolls?

[Turbo-Brown]

It's pretty easy to do one in CF dude, gimme a shout if you wanna give it a go.

Would be pretty cheap too if you can do most of the work yourself

[jaistanley]

Where would one find some nice foam that is easy to shape/work and wil withstand the resin that will be slapped on it? I fancy making some nice things in glass fibre, with a mind to eventually making my own CF airbox for my S50'd E30.

Jai

[AG205]

Anyone that can TIG weld aluminium could make you one using segments of mandrel bend aluminium tubing but I doubt it'd work out much cheaper than that guy is selling them for.

Andy

[Turbo-Brown]

You've got a few options with the foam mouldings.

The cheapest is to go to Wickes or another builders merchants and buy a sheet of 2" thick polystyrene insulation.

Glue layers of it together with an epoxy glue like araldite being careful not to get glue overlapping a joint that'll need cutting.

Make your shape, give it two coats of PVA glue and then laminate away with polyester resin and fibreglass, carbon or whatever.

Alternatively, you can use epoxy resin and a suitable reinforcement like CF or woven glass. Epoxy doesn't attack the foam, but it does attack the wallet

[oakey]

Good tutorial here for anyone interested:
http://video.google.co.uk/videosearch?h ... 4&ct=title#

Can't find any tutorials for laying cf on foam though
How do you remove the foam if the shape you are making doesn't allow for cutting it out?

[Turbo-Brown]

Just pour acetone on it and then pour out the dissolved polystyrene

[oakey]

I got some foam today and carved a rough mould I just need to carve the 'inlet tubes' and I'll post a embarrassing pic for you to laugh at

Is it a good general rule to have the internal area as large as possible?

[rob_htid]

im in the same market

[oakey]

Can anyone tell me how much carbon fiber sheet/fabric I will need to build a 6 cylinder plenum/airbox??

Measurements roughly 500mm long 120mm high and 300mm wide.

[oakey]

Here is my rough mould:


It fits in the bay no problem, in fact there is space to add more to the underside. Should I??
I need to lengthen the inlet are to aim down behind the NS headlights and generally 'tidy it up' with some sandpaper.

[ShakeyC]

whats the volume of that airbox inc the runners dude? i can work out exact size and volume for you to work to your advantage depending on whether it can be constructed to exact dimensions?

Personally the easiest solution is in your above diagram Factory S54 style because your more likely to get even cylinder filling across wider revs and not so dependant on size and volume as the CSL style one is.

[oakey]

^ Roughly 6.2 liters Shakey. Nearly impossible to work it out exactly though.

Do you think the furthest throttle will be starved of air then? I figured that hopefully the box was large enough for that not to happen?

[appletree]

Nice mold are you going to be adding trumpets inside the plenum like the CSL one? if so how and what material?

[ShakeyC]

The first two cylinders which will suffer the most in that particular design not the last mate

[oakey]

I was thinking I could just use the trumpets I have now that are aluminium. I've got a couple of sets
Could attempt some cf ones I suppose. I don't know how necessary they are really? If they're not then I won't bother

[rix313]

Isn't there a formula that relates to the angle and dimensions of those types of plenums to make sure the air distrubution is as even as possible.....or some shit?

[ShakeyC]

If it was that easy

Problem is there is so many variations and variables no single formula applies to all situations, engines, designs, applications.

[oakey]

The first two cylinders which will suffer the most in that particular design not the last mate

Ahaa Shows how much I know

Here's after a bit more shaping:

[oakey]

Here's some 3d models I made:


@Shakey- You think the design on the right is what I should go for? Does that look ok?

[ShakeyC]

Definately the right one its the easiest and most forgiving design to make

[oakey]

^Ok cool. Cheers.
I'll have to go back under the bonnet and see if I can make it fit with a central inlet.

[e21Jason]

HI

You need to extend the plenum past the last clyinder rather than blend it, and taper the plenum to give equal velocity at each cylinder.

Agree the one on the rightis more robust

[oakey]

Some links about plenum making for anyone that cares:

http://saeeng.saejournals.org/content/1/1/1312.abstract

http://books.google.co.uk/books?id=RYsg ... &resnum=10

[oakey]

HI

You need to extend the plenum past the last clyinder rather than blend it

Thanks for the reply. Can you elaborate on the above though please?

[ShakeyC]

oakey the above is incorrect and those links are bad info too, beware of what you read

[oakey]

lol! I thought the second link would be useful
Shakey- Here's the design:


Let me know what to do to make it better please

[e21Jason]

Hi

have a look at this link

http://www.ca-automotive.co.uk/show_big ... qcGVn.html

Generaly from the Bell's book "Perforance 4 stroke tuning" the plenum should over hang the runner at either end.

Think of it as two parts a plenum then the connections for the runners, each runner should see a volume of air infront of it. They whay you have drawing it there is no plenum volume infront of No. 6 cylinder

Jason

[ShakeyC]

lol! I thought the second link would be useful
Shakey- Here's the design:


Let me know what to do to make it better please

I shall design you one if you can email me a pic of your engine bay with a measuring tape laid over from bulkhead, across top of your itbs to top of your headlights/slam panel. Take pics directly above as possible please.

I will sketch it out with all the dimensions for you so its bang on what it should be.

[oakey]

Thanks Shakey.
Check you Private Message Inbox!

[oakey]

This is coming along well now I have a new mold that fits perfectly and is far more simples.
I'll post some pics tomorrow and I'll try and make it over the weekend

Get ready to be amazed by my skillz

[oakey]

I'm going to get a carbon fiber plate made up with holes cut out for the trumpets and they will be fastened to it. The hoses will then slot over the trumpets as before so runner length will be the same and the same trumpets can be used. I'll then bond the plate to the cf airbox made from the mold.
I'll use a e36m3 elbow to connect up the air filter which will probably be a shielded cone filter behind the headlights.

Just need a smaller oil cap for the rocker cover for it to fit, any suggestions?

[fowler]

looks good mate carbon is they way forward !!!!