Air intake snorkels
- Thread starter Tombo66
- Start date
Ryan experimented with them pack in the day. Lost some power
Lost some power when they were removed/modified?
Yes. Per them.
cupcake_mike
Active member
The design of an airbox in general is not to maximize flow but to pressurize the air that is there (not ram air) to maximize the benefit of the air that is "sucked in" during the intake stroke. Pretty much the reason nearly every bike with pods on it doesn't run as good as it did stock (both on sunny and rainy days). Not to mention the same situation when people cut massive holes in the airbox. Engineers engineer stuff for a reason and sometimes intake noise is part of it, but its usually to maximize engine efficiency.
If This was a test I’d give you partial credit. Let me explain….
First of all at no speed and low speeds the Airbox is not pressurized at all, it’s under negative pressure that is relative to the RPMs of the engine. That is why cars often install CAI, to create an area as large as possible to draw from. The point at which this Airbox technically gets positive pressure is when the air being (rammed in / or forced in the snorkels exceeds the demand of the engine.
Adding holes that are not facing forward wld definitely ruin the pressurization at higher speeds. But creating larger holes in the front wld definitely improve the pressurization and or help it occur at lower speeds. Make sense?
thanks for contributing to the discussion.
tombo
First of all at no speed and low speeds the Airbox is not pressurized at all, it’s under negative pressure that is relative to the RPMs of the engine. That is why cars often install CAI, to create an area as large as possible to draw from. The point at which this Airbox technically gets positive pressure is when the air being (rammed in / or forced in the snorkels exceeds the demand of the engine.
Adding holes that are not facing forward wld definitely ruin the pressurization at higher speeds. But creating larger holes in the front wld definitely improve the pressurization and or help it occur at lower speeds. Make sense?
thanks for contributing to the discussion.
tombo
Dyno testing with the ftr and various airbox mods disagrees with that theory. Especially the one about the holes in the top.
if you look at the ftrs that were racing in Daytona reallllly close you can see some secret mods.
if you look at the ftrs that were racing in Daytona reallllly close you can see some secret mods.
This is not a theory, I’m not meaning to sound crass, it’s physics. Dyno, machines never test the bike in motion so they never capture the incremental gains created at speed. This bike also has a lot of air blockage / disturbance in the front limiting it’s ability to pressurize. There are also other factors / trade offs to to consider when increasing the ram effect. To pressurize the box also means you’re decreasing the drag coefficient and possibly the handling / stability of the bike.
Very curious; what mode were made?
Very curious; what mode were made?
Tuners have been playing around with the ftr airbox for almost three years now.
we are talking about the ftr and it’s specific airbox. not other vehicles.
Look at the Daytona pictures that were posted publicly. But I’m not going to disclose race team mods.
or remove them from your bike and go have it tuned and see for yourself
we are talking about the ftr and it’s specific airbox. not other vehicles.
Look at the Daytona pictures that were posted publicly. But I’m not going to disclose race team mods.
or remove them from your bike and go have it tuned and see for yourself
Max Kool
Well-known member
Either you're asking, in which the answer is: leave them as-is, making them bigger or removing them won't help. They may look fairly restrictive, but work very well.
Or you're suggesting modding and measuring yourself, in which case the answer is: do it, and show the difference please. Many racers (and owners) are looking forward to any usable performance gains by modifying the airbox.
You can't have both. 🤷♂️
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If I offended you I apologize, but I did want to make sure to restate things that were misstated as I’m assuming people are out here to learn.
Yes, I ask what has been done,
If anything, regarding performance improvements with the air box. Always prefer to not blaze a new trail. Appreciate the intell that the race bikes have made mods, confirms there’s room for improvements. I’ll snoop around, and possibly try and replicate and report back.
thanks again,
Tom
Yes, I ask what has been done,
If anything, regarding performance improvements with the air box. Always prefer to not blaze a new trail. Appreciate the intell that the race bikes have made mods, confirms there’s room for improvements. I’ll snoop around, and possibly try and replicate and report back.
thanks again,
Tom
They are tuned for the mods as well. So unless you’re a tuner or have access to it, you won’t see anything.
Max Kool
Well-known member
You did not offend me, at all. You asked a question while being convinced at the same time the airbox/engine was choked by the intake tubes. That's just weird.
As said before, bigger diameter intake tubes do not make the bike run better, au contraire.
I'm going to take a wild guess that you do not own a dyno, have never actually seen one, or know how to tune a bike for ram air. Theoretically speaking of course.
cupcake_mike
Active member
Pressurize was the wrong word to use, sorry. I don't know what the correct word is but the purpose of the airbox is to guarantee a given (or better) volume of air available to the engine. Introducing lots of holes invites turbulance, which is counteractive to smooth "inhaling" of the engine.
That's physics.
As you said, ramming isn't really ever happening, at least to a level of forced induction where it would be of some benefit.
motormouse
New member
California Scientific
Motorcycles have had air boxes holding their air filters for decades. However, in the last couple of decades the purpose of these air boxes has changed quite dramatically.
Originally the air box was just there to keep flying dirt, rain, and bugs from directly hitting the air cleaner. They were simply an attempt to keep the air cleaner a little cleaner a little longer.
In the '70s, the US government started making noise regulations tighter. At some point, the manufacturers realized that the noise from the air intake was part of their problem. They started to look for ways to muffle not only the exhaust, but the intake roar too. Sound waves are pressure pulses in the air. Pistons pull in air on their intake stroke, creating a low pressure pulse in the air box. Then on the compression, power, and exhaust strokes the intake valve is closed and the air box is free to return to atmospheric pressure. These alternating low pressure and normal pressure pulses are sound waves. The manufacturers needed some way to dampen them out.
Your exhaust mufflers are made of a series of open chambers connected to each other by tubes. The exhaust pressure pulses get caught in the chambers and bounce around in them, then have to leak out relatively slowly through the tubes. The math that governs mufflers can also be applied to air boxes: you need a big chamber to hold a bunch of air, and an inlet tube to let air in at a controlled rate.
The air in a box is compressible, so a box is the acoustic analog of a capacitor or spring. Air has mass - about 1kg / cubic meter, about 2 pounds per cubic yard. In a tube, the air moves back and forth as a slug, as long as the frequency of the movement is small compared to (tube length / speed of sound). So, at low frequencies a tube is a mass term. Since the speed of sound is about 1000 feet per second, a foot long tube is equivalent to 1 khz. 10,000 rpm is 160 pulses per second on a V-Twin, so "low frequency" clearly applies on an air box for any snorkel shorter than about 6 feet long. A wire screen is the acoustic analog of a resistor. It slows air motion, converting the energy into heat. The combination of a box and tube is a system with a resonance. Exactly as a child's swing has a resonant frequency, exactly as a ported speaker enclosure has a resonant frequency, so does your air box.
A system at resonance is nearly perfect - there are small frictional losses in any system, but at resonance these are the only losses. Imagine pushing a child on a swing - it takes very little energy to keep her going at the natural frequency of the swing, just a little push each swing is enough. The only thing slowing her down is air resistance and a little friction in the chains. So at resonance, air flows through a tuned air box almost without resistance. This is as close as we can get to a superconductor of air.
A modern engine with valve overlap will naturally have a dip in the torque at about a third to a half the red line rpm. If the air box is tuned to have minimum resistance to air flow at this rpm, the dip in the torque curve will be partially filled in by the ease of pulling air into the engine.
So, your air box is most likely designed to add horsepower in the mid-range. The air box will have little or no effect on peak hp.
Years ago, before airboxes were designed as resonant systems, it used to be popular to cut additional holes in the air box to allow more air flow for high rpm. This is no longer a good idea. Modern air boxes can flow much more air than the engine will ever use. Modern engines have throttle bodies or carburetors with throats that are typically about 45mm in diameter, about 16 sq.cm in area. The inlet snorkel to a modern air box will be roughly 300 to 800 sq.cm - much larger than the throttle body or carburetor throat. The idea that the snorkel makes for a significant impediment to air flow into the engine is questionable at best. Drilling holes to let in more air is exactly equivalent to drilling holes in your speaker cabinets to let out more sound. Removing the snorkel from your air box is the exact same thing as removing the port in your speakers, the tube that's carefully engineered to have just the right diameter and length to reinforce the bass on your speakers at low frequencies. By altering your air box in any significant fashion, you're most likely going to cost yourself three to five hp in the mid range, and gain nothing measurable at high rpms