Siamesed Plenums

seight · Post by **seight** » Fri Mar 09, 2007 12:00 pm

adamnreeves wrote:Nope, but my trumpets are already lowered and half expecting to have to cut down the plenum also but I shall leave that until the engine is in the car and I can see how much I need to remove.

pitsnow wrote:Are you sure you will get this under the bonnet of the Westfield?
It would not on a Rush.

I would bin the idea Adam, you've no chance of fitting a siamese plenum under your bonnet. Even if you could get the plenum under the bonnet line you would need to cut holes for the hose(s) to fit which wouldn't be pretty, plus you won't have enough room for 2 air filters.
Rear facing really is the only way to go. I bit the bullet and bought a carbon plenum for mine

I don't know anyone who has fitted anything other than the factory cut n shut rear facing or the ACT carbon version. I know the Dax Rush demo car had a std plenum but that stuck out of the bonnet.
Mike

chodjinn · Post by **chodjinn** » Fri Mar 09, 2007 12:43 pm

if anynoe knows of a cut-n-shut plenum for sale let me know I'm after one! Don't wanna pay ACT ridiculous prices for some nicely shaped HB pencils lol.

pitsnow · Post by **pitsnow** » Fri Mar 09, 2007 4:33 pm

seight wrote:
adamnreeves wrote:Nope, but my trumpets are already lowered and half expecting to have to cut down the plenum also but I shall leave that until the engine is in the car and I can see how much I need to remove.

pitsnow wrote:Are you sure you will get this under the bonnet of the Westfield?
It would not on a Rush.
I would bin the idea Adam, you've no chance of fitting a siamese plenum under your bonnet. Even if you could get the plenum under the bonnet line you would need to cut holes for the hose(s) to fit which wouldn't be pretty, plus you won't have enough room for 2 air filters.
Rear facing really is the only way to go. I bit the bullet and bought a carbon plenum for mine
I don't know anyone who has fitted anything other than the factory cut n shut rear facing or the ACT carbon version. I know the Dax Rush demo car had a std plenum but that stuck out of the bonnet.
Mike

I agree with Mike. Even if you could cut an inch of the plenum, your throttle bodies would both still be outside. Have a look here how bad it is on a Rush:

http://www.daxcars.co.uk/rush/rushphoto/rush15.htm

The Westfield RV8 solution is a bad one for power. If you want to get near your target power, you need the ACT Westfield plenum. (Or ITB's)

http://www.actproducts.co.uk/inductioncomponents.php

There is a lot more to ithe ACT plenum than just a throtthle body on the end. If you want, I can send you some pictures from the inside.
And it looks oh so good.
But boy are they expensive.
Peter

adamnreeves · Post by **adamnreeves** » Fri Mar 09, 2007 5:17 pm

Thanks for all the feedback much appreciated, saved me lots of hassle and money but saying that, how can the ACT performance guys commend that sort of hard earned cash! thats higher than my budget for the rest of my engine build.

Rear facing air intake does not sound a sensible idea either, I want nice cold dense air going into my engine.

Post by **katanaman** » Fri Mar 09, 2007 5:40 pm

Pitsnow, I wouldn't mind seeing pics if you can send me some or put them on here.

pitsnow · Post by **pitsnow** » Fri Mar 09, 2007 7:35 pm

katanaman wrote:Pitsnow, I wouldn't mind seeing pics if you can send me some or put them on here.

http://i6.photobucket.com/albums/y241/p ... C_0007.jpg
http://i6.photobucket.com/albums/y241/p ... C_0006.jpg
http://i6.photobucket.com/albums/y241/p ... umpets.jpg
http://i6.photobucket.com/albums/y241/p ... enum02.jpg
http://i6.photobucket.com/albums/y241/p ... enum01.jpg
http://i6.photobucket.com/albums/y241/p ... irtemp.jpg

JSF55 · Post by **JSF55** » Fri Mar 09, 2007 8:57 pm

Great pics, could that be done in fibreglass, or would u be looking for a major fire if a blowback accoured? how would the carbon fibre one cope with it? john

Post by **katanaman** » Fri Mar 09, 2007 9:40 pm

no reason what so ever that it couldn't be done in GRP, that's why I wanted to see pics as I got quite good with GRP fixing parts of my car. It wouldn't be as light of course but will still be lighter than the standard one. That said its no more difficult to work with carbon other than to do it right you should have an autoclave. A TB will still add a fair bit to the cost mind you but will still be a hell of a lot cheaper than ACT is charging.

kiwicar · Post by **kiwicar** » Sat Mar 10, 2007 11:47 am

Hi folks
working in carbon fiber is no more difficult than ordinary GRP infact it can be easier for complex shapes... you need the right resins, epoxy not polyester, but these are better resins and much easire to work with curing times from 20 min to 24 hours. You can make a plug out of white insulation foam (ordinary polystyrine foam cut with a hot wire) and lay up straight on top of it and disolve the plug out after with celulose thinners or petrol (cant do that with polyestor resin

). you can get vacuum bagging kits from moddle aircraft suppliers it does a realy good job at getting theair out and gives a really good finnish you only need the autoclave for pre preg carbon cloth. Also the epoxy resins are much less viscous and have much better wetting properties, you dont have to work the resin thruogh the cloth with a brush and roller you just "push" it into the cloth with an old credit card from the top. you can also use cling film as a release layer on the plug if you make the plug out of wood and plaster. the only thing is you should really vacuum bag it.
Best regards
Mike

adamnreeves · Post by **adamnreeves** » Sat Mar 10, 2007 1:11 pm

This sounds a nice project for me to learn fibreglassing techniques and quite tempting! I have a davids fibreglass kit from Halfords. Can anyone give a step by step guide for making the plenum from scratch. I do not have a hot wire tool but I have a stanley knife.

Post by **katanaman** » Sat Mar 10, 2007 2:25 pm

Yes first bit of advice is don't use a davids kit lol. The cloth is poor quality at best and it will cost you a fortune. I use http://www.cfsnet.co.uk/ for all my supplies. Spooky enough they also have a methods section on their site so go have a read. Mould making and final product making really isn't that difficult although you will probably make a mess a few times before you get it right. Where the real skill comes in is making the form/buck or whatever you want to call it. This is what you make your mould from and has to basically be exactly what you want your final product to be.

kiwicar · Post by **kiwicar** » Sat Mar 10, 2007 4:34 pm

good advice Katanaman,
the halfords kits are a pain as they use lots of starch resin to hold the mat together so you can handle it while you try and put it in the hole in your wing.... the trouble is this stops it wetting out properly and makes it to stiff to mould into any corners, the resin is horid aswell to thich and goes off too quick. A visit to a good model aircraft suppliers or a good yacht chandlers to get some light weight cloth and woven Mat is well worth it. you can do allot with a good polyester resin but I much prefer epoxy laminating resin (but you must use gloves).
Making the plug is the difficult bit, for polyestor resin you need a good surface in somthing that does not react with the resin, wall plaster finnished in emulsion paint is good, but you need to get a good surface finnish, lots of sanding then polish it with about 6 layers of floor pollish and a PVA relaese agent (1 part pva glue to 1 part water and brush on 2 to 3 layers if you cant get the real stuff). Take a female mould off it then clean it polish it with floor polish a release agent again. If you use epoxy and a vacuum bag method for a one off you get a goog surface on th outside so you do not need the female mould.
To make a hot wire cutter I use a battery charger as a power supply, and a guitar string as the wire (good nickle chrome steel B or light G string depends on length) and make a wooden H frame for it and screw it on its side to the edge of a bench, rest the foam on the bench and move it into the wire make the plug up in layers stuck together with PVA and finnish it with a very sharp slanly blade, however they do blunt quickly, then sand it smooth.epoxy straight on this, or plaster and emulsion paint it (with lots of sanding) and use polyester resin (once you are sure the foam is compleetly covered). It is far easire than it sounds here.
Good luck
Mike

kiwicar · Post by **kiwicar** » Sat Mar 10, 2007 4:38 pm

oh yes for the hot wire cutter you need the wire in tension so you put a string across the back of the H and twist it like an old fassioned bow saw if you need a Photo of one I'll get the one out the shed and post it up.
Mike

adamnreeves · Post by **adamnreeves** » Sun Mar 11, 2007 11:03 am

Could you tell me what height the plenum is at the highest point?
What throttle size do they use?

pitsnow wrote:
katanaman wrote:Pitsnow, I wouldn't mind seeing pics if you can send me some or put them on here.
http://i6.photobucket.com/albums/y241/p ... C_0007.jpg
http://i6.photobucket.com/albums/y241/p ... C_0006.jpg
http://i6.photobucket.com/albums/y241/p ... umpets.jpg
http://i6.photobucket.com/albums/y241/p ... enum02.jpg
http://i6.photobucket.com/albums/y241/p ... enum01.jpg
http://i6.photobucket.com/albums/y241/p ... irtemp.jpg

pitsnow · Post by **pitsnow** » Sun Mar 11, 2007 3:30 pm

Sorry, I sold the set-up last year when I got the Weber IDF. If I would have to guess, I would say 120mm.
The throttle was sourced by myself, e-bay, 72mm fitted the opening best.
I made a deal with Tim to just provide me the plenum plus base and did the rest myself. Hence the air temp probe and 72mm throttle. It was still expensive though! But not like 500 expensive.
Just edited to say, if you make your own, make it as big and tall as you can. Your trumpets are far to short for the intended ref range of your engine. I know this is a compromise due to space. But every little helps