Mild airbox mod

[Doorag]

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.

I still stick by my original statement at the top of this thread. We don't have 'forced-air' bikes as Wavex says so it doesn't matter how big a hole we make. In theory, we could run it in the open air and it shouldn't matter as long as we filter it so no contaminates get in. All a larger hole does is make it easier for the engine to suck in the air it needs. It won't take more than it can unless we add something else to force the air in.

 

[Wavex]

I still stick by my original statement at the top of this thread. We don't have 'forced-air' bikes as Wavex says so it doesn't matter how big a hole we make. In theory, we could run it in the open air and it shouldn't matter as long as we filter it so no contaminates get in. All a larger hole does is make it easier for the engine to suck in the air it needs. It won't take more than it can unless we add something else to force the air in.

IMO, if the airbox design was irrelevant in the equation, you would not get such a big difference in engine sound. That difference tells me that cutting the airbox open has an effect on the engine. My point is that most likely, that effect is negative in terms of performance, simply because none of us really knows how to achieve the "sweet spot" without a PCIII and custom map.

 

[urbanj]

Many will cut down the intake mod but will throw an exhaust on and say that it flows so much more, they feel the power, blah blah blah.

air in air out. fundamentally it's as simple as that. maybe it wont have as much as a dramatic effect as an exhaust but i know its not going to hurt it. changing everything in front of the filter is not going to really affect the flow characteristics of the head ports, intake manifold and velocity stacks. it just makes it easier.

take a super athlete with a huge lung capacity and get him to take a deep breath through a straw. if he is allowed to exhale without the straw will he get more air the next time he breathes in? or what if he breathes in without the straw but has to exhale through it? everything adds up. which is why you need to manage the fuel side when you install an exhaust with air filter or the ever so dreadful...... airbox mod.


the guy that dyno'd lower actually dyno'd right where he should be.

THE 98 HP THE FZ6 MAKES IS AT THE CRANKSHAFT! Before to goes through the clutch, transmission, chain and sprockets and then to the road.

 

[Wavex]

Many will cut down the intake mod but will throw an exhaust on and say that it flows so much more, they feel the power, blah blah blah.

I put the Laser Quads on and instantly thought my bike had better throttle response, was faster and sounded better!

The truth?

(blue is stock exhaust, red is laser):

The placebo effect works wonders....

 

[FZ1inNH]

I have to agree with Doorag's simple explaination. The engine will only take what it needs. We're doing this mod to allow it to take more without restricting the flow, or at least, still restricted but less so. The engine will never consume more than it can possibly use.

Several have dyno'd with all bone stock. I'm waiting for one who did the same "mild" mod to dyno again with this being the only change. (Rob! Where's the new result?!?) If I could spend the extra money, I'd run two dyno's myself after purchasing a new stock cover. I'll start looking around for local dyno places. I'll believe it all when I see it myself.

For me, my nose and my seat-o-de-pants testing, I see genuine improvements. However, at no time have I ever said I had increased HP from this. Only cleaner smelling exhaust and smoother response from the throttle throughout the entire band, even quicker if you will. I cannot possibly tell you, from my arse, that I have more HP though. I can tell you the exhaust from there does smell worse though! :rof:

 

[Wavex]

I have to agree with Doorag's simple explaination. The engine will only take what it needs. We're doing this mod to allow it to take more without restricting the flow, or at least, still restricted but less so. The engine will never consume more than it can possibly use.

So no matter the amount of fuel that enters the engine, the engine will automatically take the perfect amount of air it needs for that amount of fuel? So basically, the FZ6 can never run lean then (or rich for that matter), it will always run a perfect fuel/air mixture. Well if that`s the case, I take back what I said above!

 

[urbanj]

I'm not knocking that a exhaust will make more power. we know that. but the way that an exhaust system or should i just say cans is talked about like the gospel. when really all you are doing is freeing up the flow of exhaust. all the tricky stuff that affects flow such as the exhaust port, header design and collector design and location means we are just taking out the final bottle neck in the system.

And the O2 is emissions only. Its only used during closed loop. which would be under light loads and steady cruising. at WOT the o2 sensor doesn't do anything in terms of trimming the fuel

 

[urbanj]

no the engine takes air first then adds fuel at the intake manifold right behind the intake valve.

the engine at peak Volumetric efficiency (VE) which is peak torque of 10000rpm is flowing X amount of air. by increasing the VE you can get more air. say we assume our highly tuned 600cc engine is 96% efficient it would be flowing 101.6cfm at 10000rpm at wot. by changing the efficiency we change the amount of air which can enter the engine which then changes the amount of fuel we need to add to make the most complete burn. resulting in more power.

more air, more fuel, more power

 

[krid80]

no the engine takes air first then adds fuel at the intake manifold right behind the intake valve.

the engine at peak Volumetric efficiency (VE) which is peak torque of 10000rpm is flowing X amount of air. by increasing the VE you can get more air. say we assume our highly tuned 600cc engine is 96% efficient it would be flowing 101.6cfm at 10000rpm at wot. by changing the efficiency we change the amount of air which can enter the engine which then changes the amount of fuel we need to add to make the most complete burn. resulting in more power.

more air, more fuel, more power

I agree totally but question the bigger hole causing more air to enter the combustion chamber. I guess a good analogy for my thought is a runner breathing through a 2" tube or a 3" tube. it doesn't matter.

 

[Wavex]

I'm not knocking that a exhaust will make more power. we know that.

Look at the chart again. Changing from stock to Lasers DEcreases power if done by itself.

And the O2 is emissions only. Its only used during closed loop. which would be under light loads and steady cruising. at WOT the o2 sensor doesn't do anything in terms of trimming the fuel

No, O2 is not for emissions only... it provides data (excess oxygen in exhaust) to the ECU, so the ECU can adjust the FI.

More details here: HowStuffWorks "How Fuel Injection Systems Work"

Which btw also talks about an air intake sensor (mass/volume) which the FZ6 does not have...

 

[FZ1inNH]

So no matter the amount of fuel that enters the engine, the engine will automatically take the perfect amount of air it needs for that amount of fuel? So basically, the FZ6 can never run lean then (or rich for that matter), it will always run a perfect fuel/air mixture. Well if that`s the case, I take back what I said above!

If that is what you read into it, then I guess so.

I'm stating that given a hole sized "X" and one sized "Y" with "Y" being larger, you'll get more flow through "Y". At the bottom of each hole is another hole, "Z". Z is a fixed diameter and will not change. Z will accept the volume of air that it's own diameter can possibly allow it to consume. If it is drawing from "X", it will have a challenge meeting full possible volume. If it is drawing from "Y", it has less trouble meeting that volume. If you remove all restrictions, Z will take whatever it can possibly consume and no more. Taking this into account, if we measured "Z" (four openings, one for each throttle body) and compare that measurement with "X" (the stock airbox cover opening) we discover that there is significant restriction. This isn't just on the FZ6 but on most production vehicles today. This is how aftermarket air intake companies like K&N make their money.

Within this system are sensors that read the volume of air along with the output of exhaust. The FZ6 is equipped with 4 sensors along the way. In the airbox, there is an air temperature sensor. In the intake assembly, there are the vacuum and pressure (fuel) sensors. In the exhaust before the Cat, there is the O2 sensor. (WikiAnswers - What is the purpose of an oxygen sensor) The O2 sensor detects when the engine is running rich or lean and adjusts the fuel mixture accordingly. It does not matter what the intake is accepting for air volume, the computer will learn, computate, adapt and adjust based solely on the level of oxygen or lack thereof. If it finds there is more oxygen, then it will increase the fuel to create its "sweet spot" on its own.

A PCIII goes far beyond this smart bike by allowing you to manually map the entire RPM range to obtain the performance you want. It doesn't learn, it doesn't adapt and it doesn't adjust any more than what the owner tells it to do. People who use a PCIII and do not understand tuning and dyno testing will do one of two things. They will run very rich and pollute the air or they will run very lean and ruin their engine. This is why it's best to either know what you're doing when you buy one or let a pro tune the map for you. My point in this is the O2 sensor and stock computer does not negate the need for a PCIII. A PCIII is an owners personal choice to remove the capability of the bike's ability to adapt and force it to use the map provided regardless of intake, fuel and exhaust.

If I am wrong here, someone please point it out and show me where to find the correct answer. :thumbup:

 

[Wavex]

the engine at peak Volumetric efficiency (VE) which is peak torque of 10000rpm is flowing X amount of air. by increasing the VE you can get more air. say we assume our highly tuned 600cc engine is 96% efficient it would be flowing 101.6cfm at 10000rpm at wot. by changing the efficiency we change the amount of air which can enter the engine which then changes the amount of fuel we need to add to make the most complete burn. resulting in more power.

more air, more fuel, more power

:surrender: ok you totally lost me there.... How do you change the efficiency of an engine? How do you calculate Volumetric efficiency? What does this have to do with confirming whether gutting your airbox will hyelp or hurt performance?

 

[urbanj]

a good read.

i found a good write up on a physics forum that explains what happens better than I ever could. I do wish I got into engineering though. From my point of view by not touching the box shape and leaving the hole in the top which is has a trumpet to it, nothing should be effected to ruin the "tuning". all we are doing is mildly opening the snorkel for ease of airflow.

Quoted:

"it’s possible to obtain greater than 100% volumetric efficiency in a naturally aspirated (non-supercharged) engine by using tuned intake/exhaust systems. How all this works isn’t all that complicated, but it takes a while to explain it properly. I think the first use of tuned intake runners were the vertical velocity stacks. They were generally of a length that put the open bell mouth somewhere around 15 to 18 inches above the back side of the intake valve. Although both the length and diameter of the runner are important, the length is what determines the specific rpm at which the runner is tuned to provide peak efficiency.

The velocity stack utilized the fact that air is a compressible fluid to produce its boost. At wide open throttle, with the engine turning at high rpm (the rpm that the intake is tuned for), a column of air is moving at a high rate of speed down the intake pipe while the intake valve is open. The column of air moves toward the cylinder in response to differential pressure; the pressure in the cylinder is lower than the pressure at the open end of the velocity stack. When the intake valve closes, the inertia of the column of air causes it to continue moving down the intake tube, stacking up against the back of the closed intake valve, causing the intake air to compress, and creating a higher pressure right up against the valve.

Now if the high pressure air sitting at the intake valve would just stay there until the valve opens again, life would be very simple. Only it can’t, because the pressure is now lower at the inlet to the runner. So the high pressure air bounces off the closed valve and tries to move backwards toward the inlet. Since the valve is closed, the entire column of doesn’t really start flowing backwards; instead it is more like a high pressure wave propagating back toward the inlet. This high pressure wave (or pulse) leaves a low pressure behind it, and when it finally reaches the inlet, the pressure at the inlet is now greater than the pressure in the intake tube. As a result of low pressure in the tube, air starts moving back into the tube, its inertia causing it to stack up against the intake valve again, which is still closed. If the engine is turning the proper rpm (whatever the intake tube is tuned for), the intake valve opens when this higher than ambient pressure is present at the valve.

Some of the design considerations are pretty obvious. If the diameter of the tube is too large, the velocity of the column of air will be too slow to create a good inertial pulse, or reflected wave. If the tube is too narrow it will restrict the airflow and cause a performance decrease. The length of the runner determines the rpm where any boost effect will occur. Earlier it was noted that the typical velocity stacks on old race cars were around a foot long. Since I think the reflected waves that set up inside the runner propagate at the speed of sound, I think the length is such that it is three times as long as the calculations would indicate it should be. These older types used a third order harmonic, or in other words, several of these waves would be bouncing back and forth inside there at any given time. Maybe some math people here can sort out whether this is part is correct or not. I think they used to use a foot (or foot and a half) long for an rpm around 5 or 6k. It seems like there used to be a formula that was used to make some sort of preliminary “length to rpm” calculation. Testing would still be needed to fine-tune a particular setup.

The way it was explained to me, using a length tuned to the third-order harmonic gives a very deep peak when you hit the resonate rpm, in other words a big kick. The problem with this is that it is not effective when you get off of (above or below) that rpm for which it is tuned. The much shorter stacks that are common today, and the tuned induction systems seen on a lot of cars must be using first- or second-order harmonics, I’m not sure, but that would have the purpose of making the thing effective over a significantly wider rpm band, but at the cost of not producing quite as high of a peak boost.

Exhaust systems are similar, but I think they are not quite as twitchy to get right as the intake runners are. The exhaust pulses have a significantly higher pressure differential, or power pulse, that you are dealing with, to begin with. But the process is similar, except the thing is tuned to have the exhaust valve open when the low pressure pulse is present at the back of the valve."


This is why SPOON doesn't mess with intake systems on their cars. They say HONDA designed it so well that by messing with the intake it ruins the throttle response they like for racing. it has to do with the distance those harmonics travel and bounce off the airfilter. so SPOON just makes a drop in.

 

[urbanj]

CFM the engine flows is CID * VE * rpm / 3456

VE is 3456 * CFM / CID * RPM


Who's the engineer here? I thought we had one in training. They probably could help us out here.

 

[Wavex]

If that is what you read into it, then I guess so.

I'm stating that given a hole sized "X" and one sized "Y" with "Y" being larger, you'll get more flow through "Y". At the bottom of each hole is another hole, "Z". Z is a fixed diameter and will not change. Z will accept the volume of air that it's own diameter can possibly allow it to consume. If it is drawing from "X", it will have a challenge meeting full possible volume. If it is drawing from "Y", it has less trouble meeting that volume. If you remove all restrictions, Z will take whatever it can possibly consume and no more. Taking this into account, if we measured "Z" (four openings, one for each throttle body) and compare that measurement with "X" (the stock airbox cover opening) we discover that there is significant restriction. This isn't just on the FZ6 but on most production vehicles today. This is how aftermarket air intake companies like K&N make their money.

Within this system are sensors that read the volume of air along with the output of exhaust. The FZ6 is equipped with 4 sensors along the way. In the airbox, there is an air temperature sensor. In the intake assembly, there are the vacuum and pressure (fuel) sensors. In the exhaust before the Cat, there is the O2 sensor. (WikiAnswers - What is the purpose of an oxygen sensor) The O2 sensor detects when the engine is running rich or lean and adjusts the fuel mixture accordingly. It does not matter what the intake is accepting for air volume, the computer will learn, computate, adapt and adjust based solely on the level of oxygen or lack thereof. If it finds there is more oxygen, then it will increase the fuel to create its "sweet spot" on its own.

A PCIII goes far beyond this smart bike by allowing you to manually map the entire RPM range to obtain the performance you want. It doesn't learn, it doesn't adapt and it doesn't adjust any more than what the owner tells it to do. People who use a PCIII and do not understand tuning and dyno testing will do one of two things. They will run very rich and pollute the air or they will run very lean and ruin their engine. This is why it's best to either know what you're doing when you buy one or let a pro tune the map for you. My point in this is the O2 sensor and stock computer does not negate the need for a PCIII. A PCIII is an owners personal choice to remove the capability of the bike's ability to adapt and force it to use the map provided regardless of intake, fuel and exhaust.

If I am wrong here, someone please point it out and show me where to find the correct answer. :thumbup:

Thanks Eric, I did indeed mis-understand your previous post... this makes much more sense to me :rockon:

However, the volume of air going through hole at the bottom of the airbox ("Z" as you call it ) does not only depend on the diameter of Z... you`re forgetting air velocity here... the more you cut your airbox, the more air you will get through Z, simply because you are now increasing the velocity of the air coming in. Adding a ram air for example will help you get even more air into the engine... if the logic that more air = more performance, then ram airs should make a BIG difference!

Again, I see everybody's point... and maybe you are all correct that cutting the airbox open will increase performance... I personally believe that none of us really know what it does... and if I had to bet (and based on actual dyno results ppl have been seeing), I would bet that a dyno done on a stock bike, compared to a bike with a gutted airbox would show decrease in performance. Just my opinion and I might be wrong!

 

[FZ1inNH]

Well, I'm hoping the Reiobard can get another dyno done. He did a bone stock dyno and has since done the mild airbox mod. I'm going to check with a friend in the business to see if we can dyno mine with the mod and I'll buy a stock cover to throw on to dyno the stock setup. I've done no other performance related mods so I'm a good candidate. :thumbup:

Oh, and yes, RAM air induction does create higher performance. Ever driven an old Hemi 440 with a 8-71 blower? Didn't someone say there's a super charger available to fit the FZ6? It's SOLE purpose is to RAM as much air into the intake as it possibly can by cheating the system and super-compressing it before it reaches the combustion chamber. Super chargers are actually very simple in design but very efficient in what they accomplish. Check out Speedfactory. Speedfactory Challenger

 

[Wavex]

Well, I'm hoping the Reiobard can get another dyno done. He did a bone stock dyno and has since done the mild airbox mod. I'm going to check with a friend in the business to see if we can dyno mine with the mod and I'll buy a stock cover to throw on to dyno the stock setup. I've done no other performance related mods so I'm a good candidate. :thumbup:

Oh, and yes, RAM air induction does create higher performance. Ever driven an old Hemi 440 with a 8-71 blower? Didn't someone say there's a super charger available to fit the FZ6? It's SOLE purpose is to RAM as much air into the intake as it possibly can by cheating the system and super-compressing it before it reaches the combustion chamber. Super chargers are actually very simple in design but very efficient in what they accomplish. Check out Speedfactory. Speedfactory Challenger

I can`t wait to see the results!

About the RAM air comment, I am sure the supercharger would require some fine tuning the FI... you won`t make me believe that they use the stock map for that :rockon:

 

[Wolfman]

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.

You are absolutely correct on all fronts. The guy who tuned my bike, knows his stuff, and has told me that some Dyno'S READ VERY HIGH, but that is at places where they want people to think they have a rocket ship on their hands!

The other thing that has to be considered, is that Dyno's sometimes take a few runs "to warm up", and initial readings can be deceptively low.

I am happy with my results, bike is running beautifully, and is a massive improvement.

 

[Doorag]

This is a great thread...

Anyway, just to be clear - I'm not claiming opening up the airbox will increase HP (I don't think it will) but it should have a slight impact on the response of the engine by making it easier for the engine to draw in a higher volume of air when it needs it. Don't forget, just because one makes the hole bigger, it still has to be filtered and the shape and size of the filtered air box has not changed. Therefore the information in the long post about the size and shape of the airbox, etc... would still be valid. No one is changing the shape of the box or the size of the stacks (which would definitely make a difference) they are only giving easier access to more air.

 

[Maddeth]

Wow now thats ann interesting read from start to finnish, would like to see how this ends, only had my FZ6 S2 a week so i wont be modding for a while.