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Airbox elimination?

1873 Views 10 Replies 3 Participants Last post by  Bloodshot
Would it be possible to eliminate the airbox with cone style air filters individual for each thottle body, like on the Bonnies? I thnk the sound improvement would be worthwhile, even if it didn't make more power.
ANy thoughts? If I recall the TB's poit upwards quite a bit, maybe something would have to be fabricated.
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It can be done. Try it and let us know what you find!
I have tried a bit larger and smaller volume in the stock airbox (up to 50% of one cylinder, larger and smaller), and the stock airbox is good for the stock cam timing and cylinder volume.

The airbox acts like a tuned plenum - because it is. The only bikes that benefit from airbox removal are those that (like the R3 and Bonnie) that do not have a correctly sized plenum.

Google "Helmholtz tuning" and "power".
How'd I know you'd be the first to respond? I'll look up those sites. So would I most likely cause a decrease in power?
I an a Tech junkie. ;D

First, my testing was inconclusive - just a few quick checks to see if normal volume changes had much effect.
The short duration cams with little overlap seem to prevent much alteration of intake pulse tuning from plenum volume and intake runnr length (velocity stacks).

Removing the airbox may do little. The plenum generally helps to fill in dips in the torque curve - especially at lower rpm. The stock engines tend to have tuning dips from 2700-2900 rpm, and again from 3800-5800 rpm. These can be altered (rocked around and filled in) a bit with intake and exhaust tuning changes - diameters and lengths.

If you do a few searches for 'Helmholtz plenum' and 'plenum effect', you will find more than you want to know. If you want a few links to some detailed tech info, PM me and I will dig through some old stuff and give you a few placed to get started.
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HMM, this stuff seems to be over my head, From what I gather, The airbox or Plenum, helps to create the sound? So does the airbox act like a Hemholtz chamber?

My only experience is with a cold air kit that I put on a Civic that I used to have. The sound was cool, and was a big improvement over stock.
I think i've already read more than I need to know, thank's anyways. I'll stick with the tried an true air box.
Just love that sound when you open the throttle at 7k and hear that howl, I just wanted to make it louder, but not at the cost of a choppy torwue curve or loss of power.
Your cold air kit was basicly a larger duct into the plenum. And getting cooler into the engine is always good.

A plenum is generally matched to the intake lengths, the engine size, and cam timing to get the cylinders to fill best over a wide range. There are waves that occur when the valve opens that can be used to get more air/fuel into each cylinder if the diameters and lengths are correct. The plenum helps to cancell out the negative waves and creat its own positive waves. Volume is used to determine at what rpm the effects are most noticed.

Lots of big math and R&D involved. Some bikes can use some help here, some are just fine as designed at the factory.

If this was a really high revving GP bike, more could be done than the 1050 engine allows.

If it is sound that you are after, try removing the airbox intake "snorkles", or just turning them outward. The stock ones are curved towards each other to reduce intake noise.
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HMMMM Maybe I'll try that, Or maybe see if I cant' make some that reach to some colder air. I like th eidea of your cold air kit though, I might try that as well.
On an earlier bike with a much simpler ECU.
From a thread on :

My airbox is split thanks to a crap job by an authorised Triumph dealership. They tightened the socks on to the inlet trumpets too high, then forced the fuel tank in to place. The gaffer tape fix worked for 3 or 4 months but when I rode it yesterday it was back to rough running, rpm hunting and crap accelaration just like before I found the split.
Anybody know where I can get an airbox for a '97 T595?
Well that answers the question of whether it'll run smooth or not. Thanks
If you want to know how your bike will run with pod filters instead of an airbox, just take your airbox lid off, tape down the filter, and go for a quick ride, it will be pretty obvious. I did this on my Monster a few years ago and it ran like crap, just no balls left. Now keep in mind, if you actually tuned your FI map for your new air/fuel mixture, the performance decrease shouldn't be very noticeable. I'd actually be curious to see actual dyno numbers on this. It sure does sound cool though...
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