Airbox Mod query...

The place to discuss any issues with your Aprilia, share tips and handy reference links

Moderators: Aladinsaneuk, MartDude, D-Rider, Moderators

Message
Author
User avatar
falcomunky
SuperBike Racer
SuperBike Racer
Posts: 820
Joined: Wed Jan 03, 2007 8:29 pm
Location: NEUK

Airbox Mod query...

#1 Post by falcomunky » Sun Jan 27, 2008 9:28 am

Spotted this on Ebay;
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... :IT&ih=010
I put a K&N filter in last year and noticed it was 3/4mm taller than the OE filter, (as well as having one end open, one end sealed). The difference in filter height means that the K&N is 'wedged' in the actual airbox making tightening down the bolts a bit harder, (spose the interior of the box is now a little larger too!).
Anyhoo, the person selling the above 'mod' appears to have cut both the filter and the airbox; Will this make much of a difference to performance or will it just increase induction noise?
Just curious... :smt006

User avatar
D-Rider
Admin
Admin
Posts: 15560
Joined: Wed Jan 03, 2007 1:09 pm
Location: Coventry

#2 Post by D-Rider » Sun Jan 27, 2008 10:39 am

oooohhhh that looks interesting.

I have a right game trying to get my airbox back together with my K&N - It's so easy to knock and unseat it while putting the lid back on.

Don't know whether it would just suck in a load of hot air from above the engine - and whether that would be much of a problem.

Can't help with your questions though .... sorry

User avatar
back_marker
SuperSport Racer
SuperSport Racer
Posts: 650
Joined: Wed Sep 26, 2007 4:30 pm
Location: Deepest, darkest Wiltshire

#3 Post by back_marker » Sun Jan 27, 2008 11:54 am

Yes, it would probably increase induction noise and like D-rider says, it would suck warmer air from underneath the tank, which has got to be a bad thing straight away.

I can't see this being of any advantage at all as you will be losing the ram air effect from the intakes because all the pressure produced by the ram air will be lost out of the top of the airbox instead of being forced through the filter, which is the whole idea.
Racing is life - anything before or after is just waiting.
- Steve McQueen

User avatar
Gio
Double World Champion
Posts: 6179
Joined: Sun Dec 17, 2006 8:28 pm
Location: Chertsey

#4 Post by Gio » Sun Jan 27, 2008 1:28 pm

Mmm Induction noise :smt003 :smt003 :smt003

How about fitting a chiller unit to the air ways?

User avatar
sabestian
SuperBike Racer
SuperBike Racer
Posts: 836
Joined: Sun Jan 14, 2007 11:02 am

#5 Post by sabestian » Sun Jan 27, 2008 4:49 pm

back_marker wrote:Yes, it would probably increase induction noise and like D-rider says, it would suck warmer air from underneath the tank, which has got to be a bad thing straight away.

I can't see this being of any advantage at all as you will be losing the ram air effect from the intakes because all the pressure produced by the ram air will be lost out of the top of the airbox instead of being forced through the filter, which is the whole idea.
I disagree with you completely, as usual. :smt015 :smt020

1. Induction noise is something you just cannot have enough. So that's the advantage actually. Believe me.

2. Warm air issue. So, it sucks warmer air from under the tank in. When you are waiting for the traffic lights to change. Who cares??

However, you're right in a way: this design is quite restrictive with regards to air volume being drafted away. I'd stick with Renegade style mods. More 'open' sort of design. Just a plate with a filter stuck on.

3. Ram air effect on a Falco has been discussed since she was born. It's simply not there. Anyone who's seen the ways the air has to pass on it's way to the airbox or the non existent seals between joints of air ducts will confirm that. They just were not designed with this in mind.

Besides the suction of the big jars is much more powerful than any pressure from outside. Do the search on 'the other forum', especially problems some had with turbos and superchargers.

So, the idea is actually to allow as much air as possible to be SUCKED in. This means that the less restrictive the way of the air is, the better. The bigger airbox capacity, the better. Ultimately, infinity is the capacity you're after. :smt003 That means no airbox at all. Renegade system, or Rene-lookalikes. These let the engine really breath. :smt020

Edit: there is an Evoluzione kit as well, that get's rid off the airbox lid and utilizes the bottom of the tank for it. This is for people that are emotionally attached to the ram effect, especially bronze Falco haters, like back_marker :smt005

Image

Pierre
SuperSport Racer
SuperSport Racer
Posts: 524
Joined: Wed Dec 27, 2006 9:11 pm
Location: Durham

#6 Post by Pierre » Sun Jan 27, 2008 5:38 pm

I thought you could have too much? I thought even race teams used airboxes that are pressurised at the right capacity for each gulp of the engine, ie none of them have k&n's wedged over the ends of their throttlebodys and sod all else.

I understood it (probably wrong as usual) that its like an exaust, theres an optimal size, too small is restrictive, too big is too errrr non-pressurisey

I have both types on my bikes, open with filter (i lifted tank 10mm aswell) and airbox/tank type and although I cant tell the power difference the open one guarantees a stupid fking huge grin every time

User avatar
back_marker
SuperSport Racer
SuperSport Racer
Posts: 650
Joined: Wed Sep 26, 2007 4:30 pm
Location: Deepest, darkest Wiltshire

#7 Post by back_marker » Sun Jan 27, 2008 5:58 pm

sabestian wrote:This is for people that are emotionally attached to the ram effect, especially bronze Falco haters, like back_marker :smt005
I never said I actually hated bronze and I certainly would never hate any Falco, even painted fluorescent paint. I just find it hard to believe that anyone is proud to have a bike in a colour which resembles your daily deposit in the porcelain throne.

Wouldn't say I'm emotionally attached to ram air, but I must admit it's one of those manly phrases that make you feel like your conkers are full of neat testosterone (other such words include 'chainsaw' and 'warrior'). :smt032

I have to say I agree with Pierre though, at the end of the day someone who knows a lot more than you and I about the intricacies of airbox design has spent quite a lot of time working out that this is the best design (yes, I have taken into account noise restrictions, but having seen that stupid plate they put in, IMHO, they design it right first then make a half-arsed attempt to meet restrictions).
Racing is life - anything before or after is just waiting.
- Steve McQueen

User avatar
sabestian
SuperBike Racer
SuperBike Racer
Posts: 836
Joined: Sun Jan 14, 2007 11:02 am

#8 Post by sabestian » Sun Jan 27, 2008 6:31 pm

back_marker wrote:I have to say I agree with Pierre though, at the end of the day someone who knows a lot more than you and I about the intricacies of airbox design has spent quite a lot of time working out that this is the best design (yes, I have taken into account noise restrictions, but having seen that stupid plate they put in, IMHO, they design it right first then make a half-arsed attempt to meet restrictions).
I don't know... I've seen enough widely opened velocity stacks to disagree (partially). However this may vary due to basically everything. I don't trust designers blindly (nor you do, I'm sure). Let's not start on stock exhaust, shock, sidestand... I'm sure they all could be improved. :smt002

Oh, I did not want to sound to testosterone-filled, in fact I'm in close touch with my feminine side (that would be my wifey I guess). :smt007

Referring to the Great Bronze Colour as "metallic poo" is not quite... let's say polite. We can all agree that there is one colour that you can freely abuse, I'm not going to say which one though (yellow), but stay away from the GBC.

Let's just end this dispute with everyone taking the airbox lids off for a few miles ride. If you dare! I bet my arse this will change your perspective. I took mine as an experiment, and it's been off for thousands miles now. And it's not coming back on.
Pierre wrote: although I cant tell the power difference the open one guarantees a stupid fking huge grin every time
Here you go. Hard evidence. :smt003

User avatar
falcomunky
SuperBike Racer
SuperBike Racer
Posts: 820
Joined: Wed Jan 03, 2007 8:29 pm
Location: NEUK

#9 Post by falcomunky » Sun Jan 27, 2008 7:22 pm

I do fancy extra 'audio' via an increased 'howl', (the only thing I miss about my ol' Kwack; Induction roar), so I might just give the hole-cut idea a go...
But only if someone on 'ere can guarantee a replacement airbox top-half if things go pear-shaped somehow, ('spose I could always fibreglass the hole back up if it goes tits-up?)? :smt017
... Anyone got a spare box kicking about perchance...? :smt009
Two is the magic number... ;)

User avatar
back_marker
SuperSport Racer
SuperSport Racer
Posts: 650
Joined: Wed Sep 26, 2007 4:30 pm
Location: Deepest, darkest Wiltshire

#10 Post by back_marker » Sun Jan 27, 2008 7:45 pm

sabestian wrote: Referring to the Great Bronze Colour as "metallic poo" is not quite... let's say polite. We can all agree that there is one colour that you can freely abuse, I'm not going to say which one though (yellow), but stay away from the GBC.

Let's just end this dispute with everyone taking the airbox lids off for a few miles ride. If you dare! I bet my arse this will change your perspective. I took mine as an experiment, and it's been off for thousands miles now. And it's not coming back on.
So, let me get this right, are you saying you've just removed the top of the airbox and not made any other mods? :smt107 :smt107 :smt107

Surely that means that the engine is sucking in air from underneath the tank that hasn't passed through the air filter. Sounds like one very dodgy way of getting your bike to make a bit more noise
Racing is life - anything before or after is just waiting.
- Steve McQueen

User avatar
sabestian
SuperBike Racer
SuperBike Racer
Posts: 836
Joined: Sun Jan 14, 2007 11:02 am

#11 Post by sabestian » Sun Jan 27, 2008 8:13 pm

I'm not THAT dumb back_marker.

Just do some research on 'renegade style airbox mod' or similar (AF1 forum, that includes Mille and Tuono sections, is the best source), get the basic idea that stands behind it, do some simple spannering and let the everlasting grin be with you ever since.

I've done quite a few other mods as well BTW. And the result, although not dyno'ed, is simply outstanding.

User avatar
sabestian
SuperBike Racer
SuperBike Racer
Posts: 836
Joined: Sun Jan 14, 2007 11:02 am

#12 Post by sabestian » Sun Jan 27, 2008 8:42 pm

falcomunky wrote:I do fancy extra 'audio' via an increased 'howl', (the only thing I miss about my ol' Kwack; Induction roar), so I might just give the hole-cut idea a go...
But only if someone on 'ere can guarantee a replacement airbox top-half if things go pear-shaped somehow, ('spose I could always fibreglass the hole back up if it goes tits-up?)? :smt017
... Anyone got a spare box kicking about perchance...? :smt009
I'll be glad to assist if you cock up :) As I said before, mine is not coming back on. Enjoy your experiment. Just read a lot first.

User avatar
back_marker
SuperSport Racer
SuperSport Racer
Posts: 650
Joined: Wed Sep 26, 2007 4:30 pm
Location: Deepest, darkest Wiltshire

#13 Post by back_marker » Sun Jan 27, 2008 10:32 pm

sabestian wrote:I'm not THAT dumb back_marker.
:smt003 Just checking

Another thought thta has occured to me though is that does all this free flowing air not make the bike run lean? I have a K&N filter in the standard airbox (previous owner put it there) and aftermarket (road legal) cans fitted and until I checked the plugs was quite concerned that the ECU would not be able to compensate for this. However if you are freeing up the airflow that much then surely there has to be a limit to how much latitude the ECU has when it comes to fueling?

It's always been my understanding that a pressurised airbox is used to get maximum performance from an engine due to the way the air flows round it, in the same way that different sized velocity stacks can change engine characteristics. If, as you say, that the ideal airbox size if infinite, then surely todays sports bikes would have eveolved to have no airbox at all, just the shortest and straigtest route from outside to the engine, thereby negating the constant problem they have these days of having to comprimise fuel capacity to allow the required airbox.
Racing is life - anything before or after is just waiting.
- Steve McQueen

User avatar
back_marker
SuperSport Racer
SuperSport Racer
Posts: 650
Joined: Wed Sep 26, 2007 4:30 pm
Location: Deepest, darkest Wiltshire

#14 Post by back_marker » Sun Jan 27, 2008 10:35 pm

sabestian wrote:I'm not THAT dumb back_marker.
:smt003 Just checking

Another thought thta has occured to me though is that does all this free flowing air not make the bike run lean? I have a K&N filter in the standard airbox (previous owner put it there) and aftermarket (road legal) cans fitted and until I checked the plugs was quite concerned that the ECU would not be able to compensate for this. However if you are freeing up the airflow that much then surely there has to be a limit to how much latitude the ECU has when it comes to fueling?

It's always been my understanding that a pressurised airbox is used to get maximum performance from an engine due to the way the air flows round it, in the same way that different sized velocity stacks can change engine characteristics. If, as you say, that the ideal airbox size if infinite, then surely todays sports bikes would have eveolved to have no airbox at all, just the shortest and straigtest route from outside to the engine, thereby negating the constant problem they have these days of having to comprimise fuel capacity to allow the required airbox.
Racing is life - anything before or after is just waiting.
- Steve McQueen

User avatar
sabestian
SuperBike Racer
SuperBike Racer
Posts: 836
Joined: Sun Jan 14, 2007 11:02 am

#15 Post by sabestian » Sun Jan 27, 2008 10:45 pm

I'm not THAT wise either... :smt003

What I wrote before I what I had gathered shoveling through tons of posts of people fighting to get every HP squized out of their Rotaxes.

If you free up one end (exhaust) it would be nice of you to do the same with the other (airbox).

It's not balanced properly as stock with stock anchors and airbox (to pass noise regulations). When you're designing a bike, you need to meet noise and emission regs. You put restrictive exhaust on. Then the airbox for a good measure. These sports bikes are evolving AROUND AND IN SPITE OF these regulations. I'm amazed they can tease more power out of the engines. Still. I'd love to see one or two that was not restricted... :smt007

Post Reply