I'm finally thinking of putting my MNR to proper use and hill climbing it, as thinking I might retire my little 106 at the end of the year

I have seen quite a few BEC's running original air boxes cut up to fit under the bonnet, with some owners saying it's improved performance. I have been looking at getting an R1 air box in but have had to remove basically all of the upper part (pic below) would it be worth running the box like this as not much space above the central inlet trumpets, my plan was to run the air in, in front of the centre trumpets by cutting a hole and glass fibre'ing a piece of duct in - can anyone offer any advice

I can't really answer your question but could you just use a foam filter?

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Originally posted by Rosco86
I can't really answer your question but could you just use a foam filter?

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Ah ok, would it be easier to make a fresh box from some aluminium sheet? Or a fiberglass one?

Do a search for member cosmick on here, he has just done a box for my Hayabusa, different box but I am sure the same technique could be applied.

He cuts the plastic and fusion welds it back together, here is a before and after shot from his archive.


Description

Thanks, I'll have a look - starting to think I'll stick with the foam

We have done a lot of work with airbox design and matched exhaust systems. To be honest it is largely due to gains from a new airbox that the Arion is so much quicker in the RGB races this year.
Here's a few pointers that may help.....
Volume before filter can never be big enough on a Bec
Always try and build from grp or plastic over alloy - it resonates and can cause interesting characteristics
The stand off area above the bell mouth is crucial and reducing height to lid will seriously affect power
Keep inlets relatively small on the body and taper them up in n diameter to the airbox
An airbox will always work better in terms of power delivery on a Bec than an open filter
Use the biggest area of filter material you can - it's job is twofold - to filter particulates but also to work as a damper trimming out turbulence
On a seven shape car a good area for intake is on the nose one on the corner where vertical meets horizontal surface
If you can achieve ram air pressurisation (and it is possible) small increases give big gains but tend to come in high up the speed range
A downside to achieving ram pressure is the motor can feel a little flat after braking and reapplying throttle as energy is used making the stall d air flow again
A closed throttle dump valve will help keep air flowing to stop this symptom
Use the he smoothest bore I take you can - ribbed flexi hose creates lots of detrimental turbulence and can negate airbox gains - in o e case a 5bhp loss
For this reason it is jaw important to build a good intake as airbox

That's about all I know about that - hope it's useful
Andy

quote:

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Originally posted by Andy B
We have done a lot of work with airbox design and matched exhaust systems. To be honest it is largely due to gains from a new airbox that the Arion is so much quicker in the RGB races this year.
Here's a few pointers that may help.....
Volume before filter can never be big enough on a Bec
Always try and build from grp or plastic over alloy - it resonates and can cause interesting characteristics
The stand off area above the bell mouth is crucial and reducing height to lid will seriously affect power
Keep inlets relatively small on the body and taper them up in n diameter to the airbox
An airbox will always work better in terms of power delivery on a Bec than an open filter
Use the biggest area of filter material you can - it's job is twofold - to filter particulates but also to work as a damper trimming out turbulence
On a seven shape car a good area for intake is on the nose one on the corner where vertical meets horizontal surface
If you can achieve ram air pressurisation (and it is possible) small increases give big gains but tend to come in high up the speed range
A downside to achieving ram pressure is the motor can feel a little flat after braking and reapplying throttle as energy is used making the stall d air flow again
A closed throttle dump valve will help keep air flowing to stop this symptom
Use the he smoothest bore I take you can - ribbed flexi hose creates lots of detrimental turbulence and can negate airbox gains - in o e case a 5bhp loss
For this reason it is jaw important to build a good intake as airbox

That's about all I know about that - hope it's useful
Andy

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We use shorter spun alloy bell mouths on the Hondas - improve mid to top end power and allow lower airbox without compromise - think we do a set for your engine as well - what model/year is it

quote:

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Originally posted by Andy B
We use shorter spun alloy bell mouths on the Hondas - improve mid to top end power and allow lower airbox without compromise - think we do a set for your engine as well - what model/year is it

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