Mild airbox mod

[urbanj]

I know some drill a bunch of holes but i wanted to do a cleaner version and not just cut the whole snorkel off either. I'm pleased the way it turned out. increased the opening over 100% and it sounds very good at WOT or high rpm's. sweeping across 7000rpm it kinda sounds like when VTEC kicks in in a tuned honda 4cyl.

I'm still running the stock filter as im reluctant to get a k&n or BMC for filtering. i might give in though.

I used a dremel and then some fine sandpaper to clean it up. it could be better but whatever.

the second pic is a view from looking down through the box. a lot more flow now

 

[urbanj]

thought id make this quick for comparison. i cant remember for sure but its an approximate of where the plastic went down to stock.

 

[HavBlue]

Cool, me likey.....

 

[Doorag]

I know I'm being super thick, but I don't see any difference. The first image and the image in the second post look exactly the same to me. Are you saying you cut off the lip at the red line in the second picture? Does that really increase the volume of the opening? It's Friday and my brain is obvoiusly fried...

Edit: Ah, I think I get it now. The angled part used to be closed. DOH!

 

[Doorag]

Will that mess with the FI at all or does it just make the air easier to get into the engine?

 

[urbanj]

It makes it easier for air to enter the engine. i did a crude test of running about 10psi shop air directed at the lid and there was a lot more air passing through the snorkel coming from the whole area of the whole. if you look at it from the side the snorkel bends and directs air to the filter.

also I dont know why some are so paranoid about fuel injection. I took this straight from the service manual so I can't get shot down here

"Signals that are input from the throttle position sensor, crankshaft position sensor, intake air pressure sensor, intake temperature sensor, coolant temperature sensor and O2 sensor enable the ECU to determine the injection
duration. The injection timing is determined through the signals from the crankshaft position sensor. As a result, the volume of fuel that is required by the engine can be supplied at all times in accordance
with the driving conditions.

suble changes can be picked up. if the bike runs lean from stock it will still run lean. maybe i little more but its not going to be huge. id think there would be more of an airflow difference at 0 feet of elevation vs say 4000 feet than this mod could do.

 

[reiobard]

looks good, and fairly simple. how does the seat of the pants Dyno read? or is it just louder?

 

[urbanj]

EDIT: i shouldnt have said airflow difference at elevation. i meant density. which would affect the A/F ratio if the FI system wasnt able to adjust.

that being said I feel its peppier. at speed it is making it easier for the engine to draw air in. i also ride with earplugs in most of the time so i try to tune out the noise and pay attention to the way it feels. it does feel better. and my girl could definately tell its louder.

i might spring for a high flow filter now.

 

[willoby61726]

thanks for the right up on the mod. i do believe im going to do that myself this weekend. sounds like a good and CHEAP!!! mod.

 

[pchbreeze]

That's very mild...I cut a hole little bigger than 2"x3" and I love it.
I just put in an OEM filter but only because I had forgotten how thick they are and how non-porus the K/N's are. NExt time I'm going that route.

 

[reiobard]

I'll probably do something along these lines soon, i have been very busy lately (didn't even post at all yesterday and very slow this week), but as soon as i catch up and get some more time I will do the "Free" mod, thank you:Sport:

 

[Wavex]

FWIW, some french dood on a french forum did a dyno test with and without the airbox mod (ok, his was cut open all the way, similar to what PCHbreeze did), and the tech told him it created all kinds of holes in his power band... of course he went back to the stock lid

Sure it sounds good, but how do you know you`re engine isn`t getting too much air for the fuel being injected? There are no sensors for volume of air coming in are there?

Think about it, our FI is set for the stock lid, i.e. for a given volume of air coming in... if you (for example) double the amount of air coming in, there's nothing telling the FI to adjut itself to that amount right? so now your fuel/air mixture is messed up...

I am nowhere near an expert on this, but I won`t touch my airbox until I see proof that this actually improves performance without impacting the life of the engine (running lean?).

 

[OneTrack]

I am nowhere near an expert on this, but I won`t touch my airbox until I see proof that this actually improves performance without impacting the life of the engine (running lean?).

That's my feeling about the "airbox mod" as well. :thumbup:

 

[pchbreeze]

Though many 'feel' a gain in power, some of it might be psychological because it does sound better. I have noticed a 'hole' around 6k but nothing significant at all...i can only notice it when the engine is pushed really hard...which it shouldn't be at those rpm's. I've went back and forth a few times and I feel a difference but who knows. I'm not a dyno and it might have been other senses.

Of course with that dyno, I wonder if they had a fan in front of the bike as they should to simulate the air pressure increase. There are many at sbn who have sworn there's plenty of fuel there but I wouldn't know...but I am going to seriously consider a power commander once I get my exhaust with a custom tune.

 

[pchbreeze]

Most other bikes do this mod and no one has ever had a problem.
We do have vacuum lines though, which is used for throttle body control only if I remember right...that'll effect idle, which might be why it sounds bogged down at times on start up...no big deal unless you like revving your engine on first start up.

 

[urbanj]

actually the ecu will take all the variables from the sensors and adjust accordingly. the intake pressure sensor im assuming is the map sensor. this is how the ecu knows how much air is entering the engine based by manifold pressure.

other systems used on cars used an actual flapper door or a hot wire. the required voltage used to keep the wire at a specified temp translates to the amount of air passing over the wire.

so, just by opening up the intake a little you are not going to screw it up.
the engine will draw in more air because its easier to but it will sense this and add fuel. thats what fuel injection does. now given it can only do this to a certain point and then youll need a piggyback ecu (PCIII) to add more.

and all they do (piggyback ecu) is trick the ecu into thinking there is more or less air then there really is and it will adjust from there. but once you exceed max injector duty cycle you get no more fuel.

 

[urbanj]

i havent noticed a problem at all but like i said it its MILD. people are probably passing more air with just a K&N.

 

[Khyren]

as best as I know, there is no map sensor or O2 sensor on the 04-06 bikes...

Khyren

 

[urbanj]

no o2 on pre 07 but every single fuel injected vehicle has to know how much air there is so it can know how much fuel TO inject. it doesnt just guess.

 

[Wavex]

it doesn`t have to guess bro, the map is fixed, based on the OEM/stock airbox lid.

If you want to exploit your airbox mod, you need a PCIII and custom map (done by a dyno tech). Else you don`t know what you are running.

And if the sound of your engine is different after the mod, and you can notice it clearly, it obviously has an impact on your engine (think about it man!). Put a K&N in and you won`t hear a diff... or a tiny one.

Again, it's my personal opinion based on logic and little knowledge. I am sure you are fine so enjoy it!