Whats the disadvantage to an airbox removal kit?

RyanRobot99

RyanRobot99

Street Tracker
Hey guys! new guy here,

I have an 09 Thruxton. It's amazing... I'm about to order a whole mess of parts to keep me busy this winter.

Amongst the order is the BRITISH CUSTOMS AIRBOX REMOVAL KIT.

I have a question about the down side of this kit, Is there one?!

I'm still new to bikes... I've seen before and after performance dyno tests. Its amazing what opening up the air can do.

So, what's the down side? There has to be a reason they come with an airbox.

Thanks!

-Ryan

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---UPDATED 12.30.09---
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Sean at British Customs sold me an Air Box Removal Kit today.

Now the interesting news: The bike is EFI and like the carb versions needs to be re jetted. Re-mapped in my case. Sean directed to many qualified shops in my area. Looks like I have two options 1) Have the box installed and have the computer maped with the Triumph Arrow 2into2 map. OR 2) Find some one with a tune boy, Pay Sean a fee to run my serial, give up a custom unlock code, and then have him send me the custom British Custom's EFI Thruxton map.

I'm not sure what direction to go in. Mostly because I don't know any one in my area with a tuneboy.

Apparently the Arrow 2into2 map WORKS, but doesn't utilize the bike air mod to its full potential...

Thoughts?

As of right now, ACE Motorsports in Concord CA told me to give them a call when the box removal kit comes. He will install the Arrow Map.

Any one know any one in the SF East Bay Area who can tune boy my bike and install the kit? Sean says the closest guy is in Sacramento.

--Ryan
 
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Mahart

Mahart

Two Stroke
You'll pollute the air a little more without it.

Sorry, confused that with AI.
 
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sweatmachine

sweatmachine

moped
I've ridden my bike in heavy rain many times and have never had a problem. I've run K&N filters and UNI filters, with no covers.
 
BlueJ

BlueJ

Blue Haired Freak
RyanRobot99 said:
I have a question about the down side of this kit, Is there one?!
Click to expand...

You'll use more gas getting to work. Because you'll ride faster. So you'll pick a different route to enjoy it. And that route will be longer because you already had found the short one. :)

Oh, and it leads to more mods. So it will cost you more.

And you might get cramps in your cheeks from grinning all the time when you ride.

Other than that, tho.... not much!
 
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drlapo

Hooligan
The airbox, especially on a bike with CV carbs or EFI, is a carefully engineered part of the intake system. It is designed to regulate the air entering carbs or throttle bodies and provide a still air chamber; it damps out unwanted resonances and improves throttle response its removal will adversely affect the bikes performance in low and mid range
A poorly engineered box “may” restrict high RPM performance
 
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samc

Scooter
drlapo said:
The airbox, especially on a bike with CV carbs or EFI, is a carefully engineered part of the intake system. It is designed to regulate the air entering carbs or throttle bodies and provide a still air chamber; it damps out unwanted resonances and improves throttle response its removal will adversely affect the bikes performance in low and mid range
A poorly engineered box “may” restrict high RPM performance
Click to expand...

Funny how no one who's removed the airbox has ever complained about poor low and midrange performance, poor throttle response, etc. I'm guessing one of the major design goals of the OEM airbox is noise control; it gets a lot louder with the airbox off. Of course, you're welcome to keep yours; no one's making you remove it.
 
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drlapo

Hooligan
samc said:
Funny how no one who's removed the airbox has ever complained about poor low and midrange performance, poor throttle response, etc. I'm guessing one of the major design goals of the OEM airbox is noise control; it gets a lot louder with the airbox off. Of course, you're welcome to keep yours; no one's making you remove it.
Click to expand...

actually there have been complaints after removing the airbox ; one common complaint has been a flat spot and surging on a windy day
I wonder if the "performance" gains are actually just more noise making it similar to a louder exhaust: it just feels "faster"
i have not seen a dyno sheet on a bike with just the airbox removed
I might see the benefit of removing the "shelf" but believe a large reservoir of still air is a good thing
 
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samc

Scooter
Actually, I have seen dyno runs with and without the baffle and w/wo box; removing the airbox makes a huge difference. The still air volume in the airbox is just too small. I suppose ideal would be a really big, sheltered volume, several displacement-worth (sort of like a Brooklands muffler, but on the other end.
 
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drlapo

Hooligan
does anyone have real numbres?
what is the volume of the stock airbox?
what is the CFM flow of the stock airbox? with snorkle, without snorkle
what is the CFM flow of the stock carbs?
what is the CFM flow of the stock head?
 
RyanRobot99

RyanRobot99

Street Tracker
Yes, Im ordering the airbox removal for my EFI Thruxton from British Customs tomorrow morning unless some one here convinces me otherwise.
 
PieMan

PieMan

Two Stroke
Here's a dyno that shows the performance of a 790 with a standard engine and different silencers. The three dyno traces show it running with the airbox and baffle, with the airbox (baffle removed) and with the airbox cut down with DNA pod filters.

790_ab_pods_comp.jpg
 
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drlapo

Hooligan
thanks PIEMAN that is the info we needed
so it looks like the best deal is the stock aribox with the the internal baflfe removed
that combo gives you a reasonable increse in HP and very nice torque curve and number
+ 2HP from baffle less airbox to pod filters; not that great
the baffel is coming out of my Thruxton's airbox this winter

what is causing the drop in torque at 2500 rpm?
 
RyanRobot99

RyanRobot99

Street Tracker
Forgive me if I'm reading wrong. But the airbox removed is the blue line... There is about 5 horse power added.

Isn't the airbox removal best deal?
 
BlueJ

BlueJ

Blue Haired Freak
RyanRobot99 said:
The airbox removed is the blue line... There is about 5 horse power added.

Isn't the airbox removal best deal?
Click to expand...

You're correct, there's about 5 hp from stock to airbox removed. However DRLAPO was pointing out that you get about half of that gain just from pulling out the snorkel which takes about 47 seconds if you do it with your eyes closed.

PIEMAN, can you confirm that those dyno runs were not done with stock pipes? I'd think stock pipes would have a tipover in the torque curve (and thus a kink in the hp curve) up around 6000 rpms or so where the volume of air going through the heads starts to be restricted by the capacity of the pipes on the exhaust side (at least that's what my dyno curves with stock pipes did). In that case, one might not get as much oomph from a simple snorkel pull or airbox pull alone with stock pipes.
 
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