Kriss
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| posted on 9/4/09 at 02:03 PM |
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Modifying a BEC airbox!
Modified BEC std/OEM airboxes
Hi Guys, at a recent Pistonheads event I was checking out a Megabusa, which to my surprise was running a std Airbox. Well, kinda standard, he has
turned it round, and cut and shut it to scoop in air using the bonnett scoop.
My thoughts suddenly went to my R1 Indy. That too uses the R1 5PW airbox however its air feed opening has the engine cradle bar blocking roughly 80%
of the exposed hole.
Have people ever had this problem and is it worth coming up with a better set up?
The car goes like stink and has not suffered any fueling problems as a result of this, so I dont know if it is better to let it be. But I cant help
but think this box (compared to when its in the bike) is facing downwards with no specific air channel and is blocked considerably.
Any suggestions? I am tempted to modify the box and use large induction flexible hose (my clio 6 pipercross has 15cm or so wide hose) and run this to
a wish bone opening where the arms are exposed to the chassis.
Cheers
kriss
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SPYDER
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| posted on 9/4/09 at 05:01 PM |
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Hi there. I would imagine that Mr. Yamaha spent 4 billion yen and used three supercomputers to get the airbox right in terms of airflow requirement,
noise etc.
I doubt if a "one size fits all" induction pipe arrangement is going to improve on it.
We are keeping the standard airbox on our BEC. We trust Mr. honda.
A cold air feed to the inlet area can't do any harm I wouldn't suppose. That's all we intend to do.
Having said all this a lot of the RGB guys are fitting AB Performance airboxes with presumably good results so it seems that it can be done at a
price.
I would leave well alone. You yourself say it's running fine. Just give it a cold air feed. Make sure that the area you are feeding from is a
high pressure area, otherwise air will go the wrong direction down the pipe.
Your suggested placement near the wishbones might be OK if fitted with a forward facing scoop. Maybe there'll be an aerodynamicist along soon
to say otherwise!!
Our standard airbox will stick through the bonnet though. We don't care as it is a trackday only BEC. I fully inderstand anyone wanting a low
profile setup for a roadcar.
Geoff.
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richard thomas
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| posted on 9/4/09 at 06:45 PM |
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I considered doing someting similar - standard airbox gotta be a good thing. However I decided that modding it might do more harm than good, so went
for a foam filter instead.
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BenB
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| posted on 9/4/09 at 07:04 PM |
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I'd just give it the cold air feed so ease of modification. However, Mr Honda will have been designing the plenum to fit inside the tight
contours of a motorbike. So if you did it right, a bigger plenum could liberate some ponies. However do it wrong and you'll be worse than
leaving it well alone.
Cold air induction, however will work as long as the induction kit isn't too long or narrow. Otherwise you'll be giving it cold air but
you'll be making the engine breath through a drinking straw....
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Kriss
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| posted on 9/4/09 at 07:34 PM |
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The engine is already breathing through a straw due tot he fact the engine cradle is blocking a large proportion of the airbox opening.
hmm, i want to fiddle lol
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froggy
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| posted on 9/4/09 at 07:35 PM |
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i wanted to keep my airboxes when we put the second engine in but they just wouldnt fit and using sock filters has messed up the fuelling no end. when
i finally got the fuelling right we are pretty much on the limit of injector duty to get the fuelling right all the way up the rev range. sock filters
cost me 15hp per engine  i would check with a wideband if the car is fuelling right as my car still made nearly 200hp at the wheels with the mixture
dangerously lean but the oversize radiator kept the engines cool
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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Jon Ison
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| posted on 9/4/09 at 08:25 PM |
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Which brings us nicely back to a recent "foam filters are ace" debate, they may flow but their not necessarily the best for power.
Using the same theory as the "foam filters are ace" an engine should make oodles of power by unbolting the exhaust and removing every
restriction ?
A proper designed air box is always the way to go, Ive personally yet to be convinced otherwise.
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GBaggott
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| posted on 9/4/09 at 08:47 PM |
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modified airbox
Ive modified a hayabusa box to fit, i have the same issue with the craddle being in the way.
My belief is that kawasaki, yamaha etc spent lots of money developing an airbox and achieving the maximum power.
Some tool comes along and decides a foam filter is better, the filter is too coarse and im told it causes damage to piston rings and cylinder liners.
Ive tried to replicate what is standard on the bike.
Somethings are better left alone.
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SPYDER
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| posted on 9/4/09 at 08:49 PM |
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And then there's the " airboxes only matter on carburreted engines" conjecture.
Our injected 929 Blade airbox has a cable operated flap inside that varies the effective plenum volume and causes the engine to breathe through a
restrictive looking narrow letterbox shaped slot at lower revs.( Or low throttle openings. Don't know which yet). It is operated by the same
actuator as the HIVEX exhaust valve.
Is it to keep gas speed up at low revs?
Could be a noise thing, but I doubt it.
Emissions possibly...?
It's certainly another example of Mr. Honda covering all the bases.
Leave well alone.
I agree with Mr Ison. A properly designed airbox is the only way to fly.
At least as important as a properly designed exhaust in my book.
Geoff.
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GBaggott
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| posted on 9/4/09 at 08:50 PM |
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picture
and yes that is a bit of 75mm drain pipe, ha.
 
Rescued attachment airbox2.JPG
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gixermark
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| posted on 9/4/09 at 09:35 PM |
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i wouldn't read into too much about what mr honda, kawasaki etc have done with their bike air boxes for use in a BEC !! for starters they need
to fit under a petrol tank, and into an increasingly small area in a bike.... have the noise control required, and numerous other design constraints
we don;t have in a BEC
The air boxes AB sells are made to exact volume.. and give results, they also have a very effective filter in place which is far superior to OEM in my
opinion
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Kriss
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| posted on 10/4/09 at 10:13 AM |
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i dont think the drain guuter job is a bad effort at all, similar to what i was imagining.
Any more details available on the AB performance box? costs, pictures, availability.
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SPYDER
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| posted on 10/4/09 at 01:49 PM |
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Don't neglect the noise element. The AB box is noisier than standard to my admittedly uncalibrated ears. Many trackday venues have stricter
limits than race meetings and induction noise can be a huge factor.
I'm not suggesting that OEM boxes are the be all and end all but they are surely better than a cut and shut lash up or poorly executed home
made effort.
And some well known names are offering awful looking airboxes.
The drainpipe adaptation above looks like it will be OK as it retains the OEM box to a large degree.
Airboxes aren't too expensive anyway so maybe I should be encouraging experimentation, not putting people off.
So let us know how the drainpipe works!!
There must be other people with good or bad experience of airbox modding.
Let us know.
Geoff.
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richard thomas
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| posted on 10/4/09 at 02:19 PM |
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quote:
Originally posted by GBaggott
and yes that is a bit of 75mm drain pipe, ha.
Have you managed to squeeze it in upside down?
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Frosty
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| posted on 10/4/09 at 02:54 PM |
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I agree with the majority in this post that it is difficult to improve on the design of a standard airbox when the manufacturer has spent a massive
amount of hours (and yen) on the design, carefully optimising flow etc.
However, this airflow design is only effective on a bike. When fitted to a 7 chassis, the airbox is turned 90 degrees from the flow of air and
consequently sees no ram air effect, and worse still the primary food for it is hot air from under the bonnet.
I am in the process of doing something very similar to GBaggott for my Busa - keeping the airbox as standard as I can in internal design, but altering
the air inlet so that it's both cool and accelerated from the front of the car.
This should hopefully give the best of both worlds, whilst also keeping the noise down. The bike also expects a bit of ram air in the higher gears, so
it's good to give it what it wants.
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cosmick
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| posted on 10/4/09 at 05:29 PM |
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Hi Kriss
i think the person you met with the Megabusa was me. I wanted to fit the original airbox for a number of reasons. to reduce airbox noise and to return
to Cold Air Pressurised Induction. i will be at Detling on sunday if anyone wants to see it. Blue and Yellow Megabusa. i will gladly pass on the info
to make one yourself via this site .
 
Rescued attachment MEGABUSA 037.jpg
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smart51
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| posted on 10/4/09 at 05:36 PM |
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quote:
Originally posted by SPYDER
I would imagine that Mr. Yamaha spent 4 billion yen and used three supercomputers to get the airbox right in terms of airflow requirement, noise
etc.
Whereas I think they drew out the biggest size the airbox could be in the gap between the fuel tank and the engine and did the best job they could in
the available space. I also think they worked under the constraint that no more than 3 plastic mouldings could be used and that is must cost no more
than £3.00 to make. After which they probably did do some CFM work to make sure it was good.
The 98 R1 airbox fills in the 1/3 max revs dip in torque but restricts airflow at the top end quite a bit. You might want something different.
Don't get me wrong, I'm not saying it's bad, but the sharp 90° bend in the inlet tract could be better for a start.
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gixermark
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| posted on 10/4/09 at 09:22 PM |
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my blade powered car with AB airbox passed the donington 98db driveby.... which is fairly tough to pass...
all came down to silencer for me to get passed..
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SPYDER
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| posted on 11/4/09 at 09:46 AM |
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quote:
Originally posted by gixermark
my blade powered car with AB airbox passed the donington 98db driveby.... which is fairly tough to pass...
all came down to silencer for me to get passed..
What silencer are you using?
What did it measure on the static noise test, assuming that they did one.
Geoff
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hobbsy
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| posted on 13/6/09 at 01:46 PM |
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Old thread I know but does AB do a custom airbox for the 5PW R1 yet or just the blade?
Cost?
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