Air Filtration for Race Airbox / Air Intake
 

Phil or anybody else with the race air intake & race airbox setup.
I've just been reading the threads on air filtration in the 9** section with great interest.
I'd been toying with placing the air filters over the top of each bellmouth in the airbox, but on reading this I think a solution is needed nearer the headstock. So the question is what filtration solution have you fitted (if any) to your airbox / airtube ??
cheers

Neil

On the front mask fairing, I stuck two pieces of plastic treillis, issued from an aquarium shop ... a cheap solution, why not ???

Then on the frame, a piece of mosquito net !!! (please don't laugh ...)

And into the inlet trompets, a round handmade filter managed with alloy treillis ...

As you can see, the carbon fuel tank 1993 model is open ...

... reason why I decided to make a removable obturation with carbon plate in order to secure my engine !!!

With the 926, I kept the original plastic filter referenced : 46010241A !!!
But my first solution is appropriate too ...

Phil911

exactly what I've done !

yes - I like this idea, think I'll do something similar, but I'll try to fix some sort of panel filter between it and the airbox...

but I'm not sure of this one ? I'll try and avoid putting anything into the intakes.

The tank - well I don't think it should be open ! there was a carbon plate the works bikes used - not sure if it was the same arrangement as you have made, but looks very similar.
I'm modelling an all in one tank plate (if that's what we'll call it) with the carbon plate that sits between tank and headstock - right now it's in 3mm rubber sheet and when I'm happy with it I'll take a lay up from it (while it's all fitted up to the bike) to make a carbon version.
My home scanner is not working but I'll post up the works bike pics with the plate in place - they show the tank opening all closed up.
I only say this as I've never seen any action shots / complete bike shots with the tank open like a sharks mouth !
Essentially I'm worried about big pieces of rubbish punching through the mesh, or being shredded into pieces that will still cause damage, and would like to think that there's a foam filter in place to halt this.
I guess I was just looking to see if anybody had fitted a foam filter !
My airbox is all fitted up now so I'll post pictures and also post pics of my errrm rubber tank seal.
cheers

Neil

oh and Phil your bike (s) are a constant inspiration and also a constant source of jealousy (in a nice way of course) :D
cheers

Neil

jeez, I've just noticed your number board !!! my panels are at the painters now, I need to call him to have the carbon fibre show through to make the number - it looks absolutely fantastic.
I just hope he hasn't started to lay primer yet - aaaarrrgh....

Thanks for the compliments Neil, I appreciate !!!

Phil911

Neil, you said :

"I only say this as I've never seen any action shots / complete bike shots with the tank open like a sharks mouth !

Now have a look on the following pics.
This shark mouth started on 851 models till 1992 and some 1993.
In order to modify the air intake, the mechanics fixed some adhesive tapes.
According to the shape of the tank, the carbon plate were different between 851 and 888 generations ...

Phil911

For exemple, Roche's 851 N° 3 fitted a normal tank ...

Compare to Falappa's bike ... (with the carbon plate)

Or Polen's bike !!!

Convinced ??????

Phil911

Here's a very interesting solution, regarding foam filter ...
May be your solution ???

Phil911

yes - heated agreement !! they are all closed with the plate, this agrees with all of my photographs also.

Neil

Otherwise, you can use individual foam caps, like 916 mods ... ???

Hi Neil, Steve Robins here.Iv'e been trying to get my wife to post a picture for you,only to have Phill 911 to beat us to it,with his last post.This is the way i'm intending to go,i thought maybe an early JHP/ITG lozenge shaped 916 in the airbox type,that fits over both bellmouths.A 1 or 2 bhp loss wouldn't be noticeable at the seat of the pants and would only be any good whilst braging at the bar,but the benefit of the foam filter would be priceless.My 851/916 is up at Moto Rapido being sorted out at the moment,but i haven't fitted the carbon airbox etc yet. Steve

and the filter over the throttle bodies - again I'm not sure, I thought of doing this but I'll lose a lot of airbox volume with this and I'm not certain how much power / torque is lost with this solution.
When I post a pic of my airbox fitted up I'll show what I was thinking - it may not work at all.
cheers

Neil

Oh by the way when the factory brought Pollen's 888 to Plymouth uni it had no blanking plate on the front of the tank,if you held the throttle open you could see right down the inlet track on the rear pot to the valves! Steve

Steve, I take it you mean the last photo Phil posted - if it's only 1 or 2 brake then it's the way I'll most likely look at.
I guess I'll have to try a few different solutions on the dyno to see just what happens eh.
In this way at least the intakes are pretty well protected.
cheers

Neil

gulp....

At the entrance of the tank, the airflow knows its next destination !!! ... :D

Phil911

Hi again,i vaguely remember the factory gianed 1 or 2 bhp,by raising the fuel tank of the frame by about 1".The airbox on these bikes isn't a pressurised unit like the 916,as it dosn't seal to the bottom of the tank. You will achieve a ram effect using the X shaped carbon intake,but the airbox isn't a sealed resonance chamber,hence the redesign on the latter 916/955 racers. imho. Steve

Nice shot phill which i think backs up my point, as the rear of the airbox doesn't seal to the tank,but doe's allow a large volume of cool air to sit over the bellmouths.By the way i think the mesh in the bellmouths is likely to cause some restriction without offering any worthwhile benefit,apart from small children not being sucked in!!!!!! Steve

I agree with you regarding restrictions !!!

... but I didn't to take high risks with inlet airflow, sometimes supposed to transport some out of place particles ... on tracks or open open roads !!!

""" i vaguely remember the factory gianed 1 or 2 bhp,by raising the fuel tank of the frame by about 1"""

I knew that ... Congratulations !!!

I confirm with the following pic ...
There's a high alloy item on the front part of the tank, fixed on the frame ...

Steve & Phil, I've just recently installed my 1 piece carbon airbox (it's just the lower half) and it's sides and rear edge are butted up tight against the inside of the tank. Ok there will be some air leakage under pressure but it's near as dammit sealed.
This is where my interest is coming from with the front plate to close off the 'sharks mouth'. The foam I've installed, round the side edges of the tank is non breathable petro/oil resistant and provides an effective seal between the airbox and underside of the tank.
So it would seem that the rear and sides of the airbox are closed off and it will breathe through the carbon X tubes, there's only the mouth of the tank to resolve - to my reckoning this being closed off would make a rudimentary sealed/pressurised airbox ??
thoughts...

You're making confusion between quite airflow volume (851/888) and pressurised air volume (9** generations) ...

Here's the front part of the last generation of carbon fuel tank, 1994 mod.
The seals are original too ...
Even with these seals, you can imagine numerous leaks all around the tank body.
Pressurize wasn't the main goal of the ingeniors in charge of 851/888 developments, compare to 9** generations ...

Hi Neil, both Phill and i agree on the difference between the 888 + 916 type airbox systems.If you manage to build a completely sealed air box, then there should be a performance gain, providing it is large enough.Witness the gains of the early 916 over the late 888's,but the box needs to be as large as possible,which is why the factory altered the frame on the 916 style racers,748r's and 996/8 bikes to allow a bigger box to be fitted.Then you would get into the realms of worrying about loosing airbox capacity with the fitment of a foam in the box type filter, but i still think the small loss of 1 or 2 bhp on a road bike is a price worth paying,the gains which i think are two fold.1 protection from airborne dust etc, 2 in the event of a get off and the tank coming away the foam should prevent anything large from entering the throttles, after all we aren't racing these bikes( well not in a race series). Steve

Steve, nice point - I'm pursuing the sealed airbox path (Ok as sealed as possible) and am now going with chicken wire at the nosecone and I'll knock up some kind of panel filter to sit at the cross bracing just behind the headstock. In that way the airbox will have loads of filtered air to draw on and I don't take up airbox capacity with anything else.
Having said that, your over the throttle body solution / reality check warrants being considered at the very least !
cheers

Neil

This bike has a 955 motor and is using the carbon one piece airbox + carbon X intake tubes, as far as possible they have tried to go for a sealed airbox (I know the tank has a closed front on this bike). Also note the foam around the sides to try and close off the airbox against the tank underside.
Griff you mentioned action shots of bikes with the sharks mouth closed, I'll dig em out and post em up - may be a while getting this done though as I'm faced with a minor problem of a house move this weekend :D

errrm, might help if I attached the pic :lol:

Ok, still didn't get the house move done and dusted - chains are a pain in the proverbial...but heres a couple of pics just to show what I'm thinking of regards filtration :D
it's got to go in there - forward of the X bracing tubes & usual reg/rect mount.

and just a pic of the 3 stage filter in position - I'll be putting some mesh in front of the X bracings (behind the filter) so that the filter can't be sucked through into the airbox - I'll post when that arrangement is sorted...

oh and I've positioned the reg / rect in the middle of the carbon airtubes - just behind the ecu...