Air Box Info

[TwoSeven]

Has anyone done any dyno runs with inline 4s to test the impact of having the airbox lid on and off (airfilter still in place).

If so, what happened to fuel/air and power curver (were there any drops or noticible changes).

Cheers

[sAsLEX]

once you hit speed the turbulent air will fuck shit up!!!! Just ask KK whos bike wouldn't even rev out at puke when he tried a more free flowing airbox cover!!!

[Two Smoker]

once you hit speed the turbulent air will fuck shit up!!!! Just ask KK whos bike wouldn't even rev out at puke when he tried a more free flowing airbox cover!!!

I second this, my ZXR400 wouldnt rev past 10 grand...

[woody68]

Its called an airbox for a resson.
To control the flow of air in to the engine.
They spend millons to get it right so its best to leave them a lone.

[Hoon]

Airboxes provide a boost to the midrange and help flatten out the dip in the power curve caused by valve overlap (search up airbox reasonance). Lots of clever japs with clipboards spent a lot of time getting it right. Yes some people have gotten top end gains from the improved air flow of removing the airbox but at the expense of mid range and driveability (i.e. drag racers)

You will also need to jet richer to see any improvement if any - just removing the lid will result in a bike that runs like a sack of shit..

[Lou Girardin]

The Bandit had an extra 50mm hole drilled in the top of the airbox. We had to do some major jet changes to get the A/F right, but it was then dynoed at 111 hp at the wheel, about 15 over stock. (Has a Scorpion can too.)
Torque curve is very smooth, no noticeable downside apart from the cost.

[TwoSeven]

Thanks for that, is what I figured. I suspect that the resonance and attenuation tuning is done for the area under the airfilter and the area above is just to provide the correct air volume for the intake.

I've never actually gotten round to putting the cibby on the dyno with the airbox lid on and checking the difference with it off. Its always been done one way or the other.

Because my one doesnt have ram air - apart from turbulence reasons I couldnt see why it would be worth keeping the airbox lid on and restricting air flow (it only has two small intakes at the front).

Cant afford the dyno runs at the moment to check.

[F5 Dave]

Ram air is irrelevant, or rather a different reason/mechanism. The resonance inside the airbox is matched to the engine, this is the first reason for the modern airbox.

The entry to the airbox is important however, but not always intuitive. Sometimes those snorkels are to reduce noise, but some help airflow. Always best to take stuff off progressively on the dyno, you may end up putting the last thing back on. As a rule though always best to avoid sharp edges, air flows around rounded edges nicer.