Mild airbox mod

abner said:
I hope we are all a little educated on this topic and not just shooting off at the mouth. I think we can all agree that the air has to travel thru an airbox, filter, throttle body, intake manifold, and past the valves to get to the cylinders, in that order.

Without looking at the bike... I am guessing the Intake Air Pressure sensor is going to be after the throttle body, so changing the air pressure before the throttle body will have little to no affect on the ECU.

Gutting the air box will only ease the travel of air to the filter. I'm guessing this will make the bike negligably more responsive. Gutting it will create less negative pressure in the airbox, if there is negative pressure in the airbox to begin with. As a matter of fact, I am of the belief the air box could be removed all together, because your filter would cause more restriction to air flow than the box. Going with a less restrictive filter will have little change in the intake pressure, but again will make the bike negligably more responsive. Remember, this is a fuelly that pushes fuel in, not a carborated engine that sucks fuel in.

Unless you change something infront of, or behind the IAP, ie: the throttle body or porting the valves, you will not change the intake manifold pressure drasticly enough, to the point that the ECU can't handle it.

Just my $0.02... if the IAP is pre throttle body, my therory is shot to hell.
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This is the way I think about it also. I am thinking of experimenting with running it without the airbox cover just to see what it will do. I figure the worst that could happen is fouling the plugs. I've read a lot about this and I am really curious now to see what will happen.

I bought a 99 V-Max about 3 months ago. It has an access cover on the airbox that is removed to allow easier air flow. The remainder of the lid is there just to hold the air filter in place. That thing screams in the entire range and sounds awesome. It even has louvers in the faux fuel tank cover that is just above the airbox. This is a common mod that has been done for years (since 85) and no one has seemed to have any problems. I have not found any negative feedback on any V-Max forums. And it's a fuel injected bike so it's adjusting the fuel air mixture ratio. Maybe the same thing can be done to the FZ's.
 
I'm out of my depth with a lot of the preceding discussion, but one thought springs to mind - if it was a simple matter of a bigger opening = more power, why would Yamaha have designed a small opening in the first place?

Presumably their aim is to get the best performance out of the bike, so why wouldn't they just make a bigger airbox inlet if it helped?

Of course I could be talking out of my a$$ here, after all these are the same engineers who forgot to plug in the other headlight ;)
 
One of point on Volume and size of air box is designed for filter the dusty air and, to make enough negative air pressure to make "good" velocity air flow in intake. If you ride just on really high rev, no need air box to reduce friction but, will be very poor low and mid range.

Please try pucker your lips and breathe by your self. compare with opening lips larger, your cheek movement(pressure in your mouth) and breathing velocity is defferent.

However, there is possibility that there is factor that size of box adjusted for emission reguration.
 
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Guitar Man said:
This is the way I think about it also. I am thinking of experimenting with running it without the airbox cover just to see what it will do. I figure the worst that could happen is fouling the plugs. I've read a lot about this and I am really curious now to see what will happen.

I bought a 99 V-Max about 3 months ago. It has an access cover on the airbox that is removed to allow easier air flow. The remainder of the lid is there just to hold the air filter in place. That thing screams in the entire range and sounds awesome. It even has louvers in the faux fuel tank cover that is just above the airbox. This is a common mod that has been done for years (since 85) and no one has seemed to have any problems. I have not found any negative feedback on any V-Max forums. And it's a fuel injected bike so it's adjusting the fuel air mixture ratio. Maybe the same thing can be done to the FZ's.
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VMAX is not fuel injected. They have four carbs hence the common "stage 7" jet kit.
 
SteveL said:
I'm out of my depth with a lot of the preceding discussion, but one thought springs to mind - if it was a simple matter of a bigger opening = more power, why would Yamaha have designed a small opening in the first place?

Presumably their aim is to get the best performance out of the bike, so why wouldn't they just make a bigger airbox inlet if it helped?

Of course I could be talking out of my a$$ here, after all these are the same engineers who forgot to plug in the other headlight ;)
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They have to think of a all round bike, as in noise, when you do the mod you have to be prepared for a whole lot more noise, yam would the best all round. Im sure when they race these things they dont leave the airbox standard.
 
Don't kid yourself, Yamaha is notoriuos for detuning their machines to save from any warranty issues. They don't want them to be ultra proformance machines but good all round solid machines.

For any snowmobilers, whats the first thing you do with a Yammie sled? You jet it down to lean it out... all except the Vmax4 which you had to feed the fire to make it go.
 
abner said:
Don't kid yourself, Yamaha is notoriuos for detuning their machines to save from any warranty issues. They don't want them to be ultra proformance machines but good all round solid machines.

For any snowmobilers, whats the first thing you do with a Yammie sled? You jet it down to lean it out... all except the Vmax4 which you had to feed the fire to make it go.
Click to expand...

I think all manufacturers do that for warranty. Warranty work the biggest expense in vehicle manufacturing.
 
My 2 cents worth....i did this mod, along with installing a BMC filter, and with the knowledge that i was about 4 days away from getting a PCIII, with a custom map.

When the guy who tuned my bike first put on the PCIII, he ran the stock map that came with the unit, and it produced less horsepower than stock!

Could this be proof that modding your airbox is not a good idea, without a PCIII and retune?
 
I did it this past weekend, and is louder and better throttle response. I have the SS Scorpions and no PC.... it ran lean ( some poppin on decel), and i can not tell a big difference in poppin...... maybe its just louder and i cant hear it. lol

I cut out the scoop and top rounded over flange thingie.... I plan to add so kind of filter or screen over the newly expanded hole..... Although nothing will get by the filter, it may keep leafs and other crap out.

You will be happy if you do this mod.

EDIT: I just noticed another thread "do i need to disconnect battery when fitting pc111/arrow system/k&n?".... wondering if a battey disconnect is required for this mod ????
 
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Wolfman said:
My 2 cents worth....i did this mod, along with installing a BMC filter, and with the knowledge that i was about 4 days away from getting a PCIII, with a custom map.

When the guy who tuned my bike first put on the PCIII, he ran the stock map that came with the unit, and it produced less horsepower than stock!

Could this be proof that modding your airbox is not a good idea, without a PCIII and retune?
Click to expand...

You dyno'd around 89 stock and 96 tuned right? those are normal numbers and gains. some people dyno 95hp stock. their bike may not have more power but the parameters used for the dyno run may be different than yours. as well as a different dyno itself. as long as you use the same place and get good gains you're doing good. the only way to tell would be to dyno back to back with the stock lid. but even then the gains or losses would probably be too small that even a change in ambient air temp could cause it.
 
Resetting the computer with the battery disconnect is highly recommended for the new '07 & '08 model. Prior to the new model, the FZ6 doesn't have an O2 sensor and will not learn a new map to compensate for the air/fuel mixture.

My '08 definitely re-learned. After the mod, the bike smelled like pure raw fuel coming from the exhaust. After the reset, the exhaust was MUCH cleaner, thus the map adjusted the excess fuel issue and has the bike running leaner. It's even better than pre-modded airbox. I wouldn't go back at all on this mod.
 
aussiejules said:
Less restriction better flow, if the engine can breath better in theory the engine will perform better.
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by perform better you mean more power? so... maybe a half horse gain?
but didn't someone post that they dynoed a loss of power from the airbox mod?


it isn't all quantity but quality. a higher velocity non turbulent air supply is better than an open airbox creating a slower more turbulent supply.
 
So we now have 2 ppl confirming that cutting your airbox open will decrease the bike's performance, but ppl keep doing it huh? Interesting.

I know the '07+ have an 02 sensor, but even on these, I don`t think that sensor would be able to adjust the FI map to adapt to a totally different airflow intake... if it did, why would we ever need a PCIII for any bike with an 02 sensor?
 
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aussiejules said:
Less restriction better flow, if the engine can breath better in theory the engine will perform better.
Click to expand...

That's wrong imo. More volume of air coming in doesn`t mean better performance... else you could just add HUGE ram airs in front of your FZ6 and make it 200HP?

Fuel/Air mixture for a specific displacement is the key... not just the volume of air coming in.
 
OK I am bored at work :D

Please, can someone with real engine & FI knowledge correct me where I am wrong below:

- for any given rpm, the FZ engine has a sweet spot in air/fuel mixture for best performance.

- if you change one of the these parameters, i.e. either air or fuel, you will have to change the other as well to adapt, however, if you do change these parameters, you will not get the best performance from the engine anymore (not the sweet spot anymore).

- no-one knows if the stock airbox is designed such that best performance is achieved (they could have noise restrictions forcing them to restrict the air intake for example).

- If the stock airbox is indeed restricted, no-one really knows by how much you should open it to get to that sweet spot... again, not enough air is bad, too much air is bad too.

- If the airbox is not restricted, opening it up would impact the fuel/air mixture negatively.

- The O2 sensor only senses the unburnt oxigen on the exhaust side, adjusting the FI consequently... which means that if you increase the air intake volume, the sensor will tell the ECU to give it more fuel... does more air and more fuel mean better engine performance? not necessarily! Again, it's the sweet spot we`re looking for...


Conclusion: can anyone open up the airbox randomly and be sure it increases their bike's performance? I don`t think so. As a matter of fact, imo, chances are you will do the exact opposite, and we now have two people who dyno-ed their FZ and confirmed that without a PCIII + custom map, the airbox mod is hurting you more than anything else.


The above was based on my own logic and I am far from being an expert in engines... so again, anybody with real engine & FI knowledge, but let us know your thoughts.
 
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