Air Box Lid

BISavage

BISavage

champion rider
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Ive seen the video and a bunch of pictures of different air box lid designs but one I found that in google struck me as interesting:

Screenshot_20220131-155550_Samsung Internet.jpg

Does anyone recognize this, or know what the deal is with this one?

Looks like some strange foam cut into a velocity stack.

And some foam as a prefilter... which must have some impact on flow through the lid as the air following the path of least resistance must choose the snorkel path until the snorkel efficiency is exceeded...
 
BISavage said:
And some foam as a prefilter... which must have some impact on flow through the lid as the air following the path of least resistance must choose the snorkel path until the snorkel efficiency is exceeded...
Click to expand...
The opposite must be the case. With an open airbox the main gain in performance is at lower/mid revs. It seems that the volume of the airbox itself is just to small for the bouncing waves of the big single cylinder engine. Opening the box gives a little additional volume.
 
I read that the snorkel are actually ram air ducts which are boosted at higher speeds by the positive pressure at the rear of the bike, which is also why the tail light is sealed.

In a dyno or at low speeds ram air effects are not measureable.

And under low speed torque and on a dyno also seems to be the times when the open lid "works"
 
BISavage said:
I read that the snorkel are actually ram air ducts which are boosted at higher speeds by the positive pressure at the rear of the bike, which is also why the tail light is sealed.
Click to expand...

I don't know where you read that, but that seems highly unlikely. The Vit will never reach speeds that will create pressures high enough to 'boost' the intake pressure.
The snorkels are there to lower the intake noise levels. And the tail light is probably sealed to keep crap out.
 
Well the thing is, a dyno is not dynamic.

And yes "boost" is a strong word, but still may be worth 2 tenths in the 1/4 mile or in the hot lap at the track.

Has anyone done any real testing with different setups, like at a gas pump, or round a track?
 
If you take the lid off it will be obvious to your “Butt dyno” it works. Totally different ride. I put the lid back on once to see if it was just in my head and the bike felt like it was being smothered.
 
I just seen the interesting lid design and it got me measuring the air box and snorkels and stuff... and then it got me calculating with my algebra calculator... and then I was wondering which considerations were made when selecting which modification to the airbox lid/snorkels/filter, if any, and which results were to be expected in real world situations.
 
The airbox volume should be at least 10x the size of the engine. For the pulses of the single cylinder even more. In theory for the 701 airbox 7000-10'000 ccm volume.
Airbox resonance is an very important factor and I'm curious to hear about your calculations. Engeneers had to deal with a small motorbike and noise reduction and this is what we've got. If we drop the noise limit as a coefficient, one possibility is to open the airbox for better filling.
 
So, the engine side of the filter is not being changed with most options.

The filter / filter material is also not being changed.

Then, in which cases is the pre-filter side of the airbox "working" to improve the efficiency of the engine beyond that which a filter with no air box past it would? And at which speeds is this optimization targeted?
 
Up to now, I have seen images of no lid, 2 hole lid, 3 hole lid, 5 hole lid, 3 hole with stack like in the first post, or..
Stock lid with no snorkel, upgraded snorkel, or
No lid no snorkel...

With all this mod options, I wonder which one the MAP sensor likes best... 🙈
 
The Manifold Absolute Pressure Sensor gives just the signal to the ECU and the ECU does whats written in the mapping. Start with some basics and you will understand how challenging airbox mods are. Put the airbox on a flow bench and it will only tell you the half of the truth. When the airflow hits the closed inlet valve it gets compressed, expands again and at rolls back into the airbox. It is not hard to imagine that this creates turbulences that have to be overcome for the next stroke. Specially if the box is not big enough for the engine. At high revs the roll back is shorter and the engine can benefit from the still compressed mixture for a better filling of the combustion chamber. This is why you can drill as many holes as you like in to the airbox and you won’t gain any more peak performance. If you drill two or three holes it will only make a marginal difference. Best results you will probably have by removing the lid completely, or lifting it up. If you want to keep the noise level down options are very limited. If only for track the Pirates power tube might be the right route. My 2 cents.
 
Well, has anyone tested the difference in the real world between no lid, no snorkel, hole lid?

Like with laptimes, or fuel consumption, or top speed?
 
The comparisons you mention have to many other input variables than just the airflow and out of that the filling of the cylinder.
So there won't be any pinpointing possible regarding the mod at around the air filter box.
 
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