anyone with a 07' 08' ZX6R might be interested in this

[Dave]

http://www.motorcycle.com/gallery/gallery.php/d/172168-2/2009_Kawasaki_ZX6R_ZX600R_09_INTAKE_FUNNELS.jpg

for 2009 kawi has come up with a innovative low tech way to get the effects of a variable intake system like the one the R6 uses. basically they have made a combined velocity stack funnel that draws from the long part at low speed and the shorter stack at high rpm. anywho, after seeing the above image i started poking around through the OEM parts catalogs on bikebandit and it looks like the previous generation bikes can fit these funnels as well. might be good for a modest bump in mid and top end power since the 07 08's used the standard two short two long setup.

[Dave]

almost forgot to mention, from bb funnels usually run 9-15 bucks a peice so it would be a fairly cheap mod

[Mr Lefty]

intresting... still confused how that all works...

[Dave]

i started writing a book to try and help out and then got lazy and stole someone elses

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.

[Dnyce]

what size are they? its a good cheap idea, if they could fit other bikes too...or u could buy em, cut em up and mold your own if you're handy...which i claim to be...just too lazy to look up throttle body sizes lol

[Dave]

dunno about the total length but ive found calculators online in the past so its def possible and the molding idea isint illegal as long as you dont sell em ;)

[Dnyce]

dunno about the total length but ive found calculators online in the past so its def possible and the molding idea isint illegal as long as you dont sell em ;)

too lazy to sell em...well advertise that i sell em lol-but i was referring to the width/opening. thought u might know already b4 i search maybe i luck out and they mount right up ya know?

[Dave]

looks like 38mm

[Dnyce]

thx-ill let u know if i try it

[Dave]

word.

[Mr Lefty]

ok... but looking at this... you'd have to figure out the math of tune'n it... so other than Kawi riders... with the same motor... you could fuck up your performance my trying this... unless you can tune it yourself... right?

[Dave]

and thus the online calculator. you would just need to know your desired rpm peak and the length of the intake runners to where the stock funnel matches up.

[Mr Lefty]

and thus the online calculator. you would just need to know your desired rpm peak and the length of the intake runners to where the stock funnel matches up.

didn't see the online calc... :idk:

[Dave]

didnt post one just said they exist :lol:

[Mr Lefty]

didnt post one just said they exist :lol:

oh... well fuck you then... :lol:

[Dave]

right back at ya buddy!

[smileyman]

Someotimes you can tune yourself out of contention. As for me if the 600 isn't fast enough your not riding it right or you need to save up some coin and trade it for a 750 or 1000:idk:

Really i have seen bikes with a 10-15 hp deficeit own bigger faster better prepared but poorly ridden machines. And I am thinking the small advantage you would get in the mid range or in transition from low to hi rpm would be very neglible and something you could mask easier and with less effort with proper gearing...:idk:

[Dnyce]

Someotimes you can tune yourself out of contention. As for me if the 600 isn't fast enough your not riding it right or you need to save up some coin and trade it for a 750 or 1000:idk:

Really i have seen bikes with a 10-15 hp deficeit own bigger faster better prepared but poorly ridden machines. And I am thinking the small advantage you would get in the mid range or in transition from low to hi rpm would be very neglible and something you could mask easier and with less effort with proper gearing...:idk:

if you're in a 600 class, u cant go up to a bigger bike, and any small adv is beneficial right?

i like to try stuff like this-when i have the time-just because. its interesting to me, if i do x, how does it affect y, crap like that. maybe it would make the transition near nonexistant, so u dont have to mask what isnt there. but im not racing it, and i cant ride it to its limits now(unless its just a straightaway :lol: ), so its just a mechanically cool thing to try.

also i notice in the pic, that the extra middle piece is in a different spot on the two, looks similar to the stack kits that use two long and two short ones

i wish i had unlimited funds, id try all types of shit on the dyno/wind tunnel

[Dave]

Someotimes you can tune yourself out of contention. As for me if the 600 isn't fast enough your not riding it right or you need to save up some coin and trade it for a 750 or 1000:idk:

Really i have seen bikes with a 10-15 hp deficeit own bigger faster better prepared but poorly ridden machines. And I am thinking the small advantage you would get in the mid range or in transition from low to hi rpm would be very neglible and something you could mask easier and with less effort with proper gearing...:idk:

im not gonna sit here and say that tuning replaces riding ability, however what it can do is increase ease of riding and the enjoyment thereof. it also allows you to adjust the bike to your riding style. :rockwoot: