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Being as the plate and intake covers out by the frame are BEFORE the air filter wouldn't it make plenty of sense to remove them, making more air available to enter the velocity stacks? The velocity stacks AFTER the filter are the important piece that nobody is messing with for a reason. Please correct me if I'm wrong!
 

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Being as the plate and intake covers out by the frame are BEFORE the air filter wouldn't it make plenty of sense to remove them, making more air available to enter the velocity stacks? The velocity stacks AFTER the filter are the important piece that nobody is messing with for a reason. Please correct me if I'm wrong!
in a well-built, balanced engine, It's way more important to have all 4 cylinders equally fed than getting 1 or 2 random CFMs here and there. If space wasn't a problem, airbox would probably be made larger to keep cyl 1-4 from air depletion. Something that can't be done in the tight confines of a modern motorcycle.
 

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in a well-built, balanced engine, It's way more important to have all 4 cylinders equally fed than getting 1 or 2 random CFMs here and there. If space wasn't a problem, airbox would probably be made larger to keep cyl 1-4 from air depletion. Something that can't be done in the tight confines of a modern motorcycle.

So how does that plate, which seems to funnel air into the center of the air filter keep air equally distributed to each cylinder? Common sense says the two outside cylinders are working harder to pull air in this setup. This would point more towards the argument of the plate being a noise reducer and nothing with performance.
 

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"seems" is the keyword. There are large openings left and right for air distribution. The center hole may be misleading you to think there is more air going into the center but sometimes airflow can act a funny way that defeat comon sense. Only extensive testing in a flow bench will provide valuable data.
 

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Valid point. That would be cool to see some legit data, if any, from Suzuki engineers on this. I'm sure no one here is doing extensive flow testing on it! Still doesn't make sense that this is a performance item since this is BEFORE the air filter. The air will slow and spread out a bit when it hits the air filter. If this was AFTER the filter I would believe it would have performance characteristics.
 

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When I got my ecu reflashed removing the airbox restriction plate was required for the new tune to work. Just saying. This was dynoed and the results dictated this change.


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Valid point. That would be cool to see some legit data, if any, from Suzuki engineers on this. I'm sure no one here is doing extensive flow testing on it! Still doesn't make sense that this is a performance item since this is BEFORE the air filter. The air will slow and spread out a bit when it hits the air filter. If this was AFTER the filter I would believe it would have performance characteristics.
Not sure about that. I'd be more prone to think that the filter will expel air exactly the way it went through rather than spread it even. But that's just me.
 

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When I got my ecu reflashed removing the airbox restriction plate was required for the new tune to work. Just saying. This was dynoed and the results dictated this change.


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That screams that it is a noise reduction plate then. Out of curiosity do you have a dyno sheet?
 

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Personally I looked at the engineering design. It seems that the restrictive plate and the flaps covering the intake outside the frame are afterthoughts. As if the engineers designed the engine and some lawyer forced them to restrict the intake. I'll stick with that story when I go to bed at night.


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I had full exhaust replacement and installing K&N filter so I am planning to remove my restricted plate in the airbox as well.If we can call this restricted plate and not something different. Any dyno results about this?
 

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I had full exhaust replacement and installing K&N filter so I am planning to remove my restricted plate in the airbox as well.If we can call this restricted plate and not something different. Any dyno results about this?
I can't see hows its not restrictive in someway but the most noticeable difference is a nicer intake roar
 

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I have been reading here, thinking to do this air intake mod, as I have Arrow headers and ECU flash. In the Suzuki parts diagram, the part is called "seperator", not "restrictor" plate.

So the air enters from the bottom of the airbox and then goes through the seperator plate, then through the filter to the engine. As said before, wouldn't the filter itself act as a "diffusor" or seperator if the plate wasn't there? In all my thinking (no air flow engineer who really knows their sh t has chimed in here to explain why the plate is there), I would guess the plate is there to calm and slow the air down before it enters the filter, ie., calm the turbulence.

Earlier in this thread, it was shown that in the Z1000, the "diffusor" plate is perforated with holes. That makes sense. Calm the turbulence down, but let as much air as possible pass through.

So I am the first guy to suggest drilling multiple perforation holes in the plate, without removing it completely! Maximum calm air to pass through.

Unrestricting the frame air intake holes also makes sense. Maximum air in, maximum air out (with full aftermarket exhaust and ECU flash)

However, when I got my ECU flashed by Dano's. he asked me if I was going to keep the OEM air filter or replace with aftermarket. He said aftermarket gives "a couple of hp more", on Dyno, gains barely noticeable.

My conclusion: this mod might make the intake sound/noise more cool, but offers MINIMAL GAINS, but certainly gives me one more thing to tinker with this Sunday! Can't wait!

But then I think ... you know how close to ram air we have on this bike's intake system? The intake holes are already there in the frame allowing direct air entrance to the airbox ... I'm going to develop external "scoops" outside the plastics to the frame holes to pick up and force air into the airbox! The faster I go, the more air forced into the box. Now we're talkin'! GSXS with ram air!
 

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I have been reading here, thinking to do this air intake mod, as I have Arrow headers and ECU flash. In the Suzuki parts diagram, the part is called "seperator", not "restrictor" plate.

So the air enters from the bottom of the airbox and then goes through the seperator plate, then through the filter to the engine. As said before, wouldn't the filter itself act as a "diffusor" or seperator if the plate wasn't there? In all my thinking (no air flow engineer who really knows their sh t has chimed in here to explain why the plate is there), I would guess the plate is there to calm and slow the air down before it enters the filter, ie., calm the turbulence.

Earlier in this thread, it was shown that in the Z1000, the "diffusor" plate is perforated with holes. That makes sense. Calm the turbulence down, but let as much air as possible pass through.

So I am the first guy to suggest drilling multiple perforation holes in the plate, without removing it completely! Maximum calm air to pass through.

Unrestricting the frame air intake holes also makes sense. Maximum air in, maximum air out (with full aftermarket exhaust and ECU flash)

However, when I got my ECU flashed by Dano's. he asked me if I was going to keep the OEM air filter or replace with aftermarket. He said aftermarket gives "a couple of hp more", on Dyno, gains barely noticeable.

My conclusion: this mod might make the intake sound/noise more cool, but offers MINIMAL GAINS, but certainly gives me one more thing to tinker with this Sunday! Can't wait!

But then I think ... you know how close to ram air we have on this bike's intake system? The intake holes are already there in the frame allowing direct air entrance to the airbox ... I'm going to develop external "scoops" outside the plastics to the frame holes to pick up and force air into the airbox! The faster I go, the more air forced into the box. Now we're talkin'! GSXS with ram air!

If you look at a used air filter coming out of the bike then only the centre portion is dirty, showing that the restrictor plate reduces air flow to a large part of the air filter, I don't see how that can help in any circumstances.

Secondly a plate with holes in it can only cause more disturbance to the air flow, I feel that the only way to calm the turbulence down would be to have thousands of tiny holes - OH! bugger someone already thought of that - Its called the air filter....

Thirdly, Ram air - our ECU doesn't have the facility to increase fuelling as speed rises (nor different fuel maps for different gears) and thus RAM air pressure increases unlike GSXR, Hayabusa etc so if you produced an effective RAM air system you may find yourself running lean at high speed
 

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That's what I think too PP, the filter itself would act as a diffuser to calm the air turbulence, but I don't see how drilling multiple holes (like the Z1000 diffuser has) would "cause more disturbance to the air flow", it would allow the plate to pass more air to the filter, without removing the plate entirely. The plate is there for a reason thought necessary by the Suzuki engineers.
 

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That's what I think too PP, the filter itself would act as a diffuser to calm the air turbulence, but I don't see how drilling multiple holes (like the Z1000 diffuser has) would "cause more disturbance to the air flow", it would allow the plate to pass more air to the filter, without removing the plate entirely. The plate is there for a reason thought necessary by the Suzuki engineers.
I still think its mostly there to keep the noise down, but an interesting calculation below for minimum K&N air filter area (unfortunately in Imperial units) from K&N

A=(CID X RPM) / 20,839
A = effective filtering area
CID = cubic inch displacement
RPM = revolutions per minute
at maximum power

61*11,000/20,839 = 32 sq. inches 206 sq. cm

Now anyone who has replaced their filter with the restrictor plate in place will have noticed that only the part in line with the hole is dirty, and this has from memory an area of approximately 120 sq. cm possibly restricting power
 

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still trying to figure out the numbers above and how they relate to the letters. You are saying with plate the air intake area is 120 cq.cm, and we should have at least 206?
 

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Ok, Then what makes the induction noise?
Air rushing into the air box must be hammering against something to make noise. If it was just air going though those 2 small hole's, it would whistle at a pitch like a turbo pop off valve.
I was looking for inspiration on air box design in a Kawasaki Au web site, and there was a mention and microscopic picture of a Z900 air box internals.

There was brief statement that the holes in the separation plate (called because dirty air /filtered air either side) were located at the top side to direct the induction noise towards the Rider (escaping any noise test).
So, those like P Paul who jettisoned the plate, is that plate able to slightly move back and forth, like in a rubber gasket, to allow it to resonate like a speaker cone to make noise?

On an old Kawa Forum site, there was a Member who had a Version 3 Z1000. That bike had a slotted separation plate. That bike made a forcefully pleasant induction roar.
The Version 4 come along (didn't know it had so many) where they changed the plate design by having removed the slots, replacing it with around 16 or so holes.
He bought the new plate, and found the intake roar was very reduced, but the seat of the pants dyno was about the same. Of course, he reversed the change.
The Kawa box is not the same as the GSXS, as it has internal snorkel hoses about the diameter of the holes in the GSXS plate inside the filtered volume of the box.

I can't get my head around all the physics that are going on in the air box at the same time. Engine intake valves opening and shutting, the Intake Air Temp sitting at the top of the box, swirling air in spirals.
At least we no longer have the vacuum operated gate plate that 2000 era bikes had to make the noise levels quieter at low RPM's, that gone down to the exhaust pipe as the SET valve.

Rob.
 

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Sure this subject has been covered previously on the forum.

J33 dyno tuning in the UK tried this mod over many dyno runs and reached the conclusion that it made no difference to performance.

Tend to believe the clever designers at Suzuki put it in for a good reason so trusting their judgement and left mine in.

I run Decat, centre muffler delete, stock manifold with valve and stock pipe, K&N and an ECU reflash tuned on the J33 Dyno to get smooth pick up from 1500rpm, tiny burble at about 2500 rpm and then unburstable pull to the extended redline 12.2 to 12.5k (cant remember which) where it is still holding 140hp. Maxed out something around 152 hp and 81 foot lbs.

Having done the mods on my bike I like the louder exhaust but question if they were really necessary or worthwhile, good talking point though.
 
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