The Velocity Stack Guide

[MikeSomething]

Ok, I ALREADY did a search before you guys say anything...
No one seemed to really give much input.
So, here we go:
You guys have four rubber stacks in your airbox that go small stack, big, big, and small...

What combination does what?

What if I change out both bigger ones and have just four small stacks and vice versa?

What gives me more low end, and what gives me more high end power?

Is it true the factory stacks are to small and to large?

Should I just waist $279.00+ on billet velocity stacks that claim 4-9hp? Thanks!

[Commuta_Busa]

if you want to loose out on some bottom end torwue than go all small. If you want to retain the bottom end than keep them the way they are. Go +2 on the rear sprocket and that'll help give you more of a low end kick.

[jsjdjn]

Unless you race for money they all are a waste. Or as a hobby do it and have fun.

[MikeSomething]

Originally Posted by jsjdjn

Unless you race for money they all are a waste. Or as a hobby do it and have fun.

It's a hobby, a fun hobby like most. Which of those options are you telling me to do man?

Originally Posted by Commuta_Busa

Go +2 on the rear sprocket and that'll help give you more of a low end kick.

Already there. MODs in sig.

[Mr Bogus]

Originally Posted by Commuta_Busa

if you want to loose out on some bottom end torwue than go all small. If you want to retain the bottom end than keep them the way they are. Go +2 on the rear sprocket and that'll help give you more of a low end kick.

Originally Posted by jsjdjn

Unless you race for money they all are a waste. Or as a hobby do it and have fun.

dang, these two took all the good answers already..

I will take the bad one then...

you gotta go out and blow $200+ on some shiny billet ones so you can hide them in the airbox and feel like you are going faster.... :flame-on:

[MikeSomething]

Originally Posted by Mr Bogus

you gotta go out and blow $200+ on some shiny billet ones so you can hide them in the airbox and feel like you are going faster.... :flame-on:

Thanks man, great. From what I've heard, the "Shiny" ones are alil longer then the small "Not Shiny" stock ones. Again, people have said, the stockers are to long and to short. So the aftermarket Velocity stacks are a middleground to create both low and top end power. But no one on this forum who has tested them is saying Yay or Nay.

[Commuta_Busa]

There is a reason behind the OE setup of shorts and longs. The fuel and ignition maps are taylored for the OE setup.

[MikeSomething]

Originally Posted by Commuta_Busa

There is a reason behind the OE setup of shorts and longs. The fuel and ignition maps are taylored for the OE setup.

Awesome, but if someone who had...let's say a power commander, and got a custom map, wanted to go faster for some stupid reason and thought he might get a few extra ponies by changing the OE setup? What do you think he should do to that stack setup?

BTW...How the hell do you ride that thing in Carteret w/ all those potholes?

[Mr Bogus]

then you go buy two more OEM short ones... moves the torque curve up a bit..

OR a $250 set of shiny ones...

velocity stack just works by using the momentum and weight of the air to pack some pressure behind the intake valve at WOT.. (little or no benefit at anything less than WFO)

As the air velocity picks up, the less stack is needed for the effect and this is where the fun starts.. you can actually hurt a motors performance with the wrong setup..

you can see the effect with a timing light on some motors as the air pulses come right back out the top of the stack with a bit of fuel mist in it.. We used to tune the stack length until that mist was right at the edge of the top of the stack..

IF I had a video camera operator, I could show you the effect with water..

take a 1" tube about 3' long and submerge in a tank of water (fish tank works nicely)
cap the end of the tube with your hand and raise the tube until it is most of the way out of the water..

NOW... very quickly, remove your hand and put it back on allowing about half that water to go back in the tank..

When your hand covers the tube back up, you will see what looks like a spring action as the water bounces up and down in the tube a few times..

The Velocity stack does that same "air spring" thing but much faster and shorter.. you will see where at one point, you could get a negative pressure effect in the tube (not good for tuning) and a positive pressure on the other end of the cycle (what you are looking for)

oh wait a second.... does anyone know what a timing light is today?

[MikeSomething]

Originally Posted by Mr Bogus

then you go buy two more OEM short ones... moves the torque curve up a bit..

Timing light, is that a new kinda motor? Haha. Hate to sound like an annoyance...Have you done this before on your bike? I'm just tryin to get an idea here if it's gonna be something decent to do to my bike or not, and stock shorties would only run me about $10.00...

The cheap weekend MODs are running out!

[Commuta_Busa]

There's sacrifice some where to get some benefits. If you go all shorts you can gain some (very small increase) on the top end. You'll loss more on the bottom end though. Your "area under the curve" will be lower. Yes you can adjust the fuel to the inside cyclinders through certain power commanders but it's only a fuel trim feature. You can't change any spark timming just for the inside cylinders.

Yea lots of pot holes in Carter-ico and my drag seat isn't very forgiving either. Until I put street gears back on my bike I don't take it out often. 1st gear is good until 90+mph so I'm always stuck in first.

Since you're in NJ, let me know if you want to borrow a set. This way you can see how it feels. I'm less than a mile from the NJTP so you can take a quick high speed blast (at your own risk).

PM me if you're interested. I can check tonight if I still have a set.

[MikeSomething]

Originally Posted by Commuta_Busa

There's sacrifice some where to get some benefits. If you go all shorts you can gain some (very small increase) on the top end. You'll loss more on the bottom end though. Your "area under the curve" will be lower. Yes you can adjust the fuel to the inside cyclinders through certain power commanders but it's only a fuel trim feature. You can't change any spark timming just for the inside cylinders.

Yea lots of pot holes in Carter-ico and my drag seat isn't very forgiving either. Until I put street gears back on my bike I don't take it out often. 1st gear is good until 90+mph so I'm always stuck in first.

Since you're in NJ, let me know if you want to borrow a set. This way you can see how it feels. I'm less than a mile from the NJTP so you can take a quick high speed blast (at your own risk).

PM me if you're interested. I can check tonight if I still have a set.

Sounds good. Shoot me a PM w/ your number... Hopefully the weather holds up.

[tex_garza]

[MikeSomething]

Originally Posted by tex_garza

That just says it all.

[dmrowe]

Finished Performance Modifications

I went the route of Factory Pro to see if their claimed performance measured up....NOT! With the rest of my mod's I used the (4) short OEM stacks and got 178 HP, with the Factory Pro billet stacks only 171 HP and at top end the power curve dropped off like the edge of a cliff. Sold the stacks for a song but learned a lesson...oh yeah and I only use 87 octane pump gas too!

[MikeSomething]

Originally Posted by dmrowe

Finished Performance Modifications

I went the route of Factory Pro to see if their claimed performance measured up....NOT! With the rest of my mod's I used the (4) short OEM stacks and got 178 HP, with the Factory Pro billet stacks only 171 HP and at top end the power curve dropped off like the edge of a cliff. Sold the stacks for a song but learned a lesson...oh yeah and I only use 87 octane pump gas too!

Ok, from what I make of this, you're saying the 4 short OEM stacks gave you more noticable gains, and you tried the other ones and they sucked so you kept the 4 short ones on there? I'm guessing you don't have a dyno sheet w/ your stock 2 big and 2 small stacks setup w/ the other new MODs?

[mattstang]

dont waste your money on the billets. go with the rubber oem shorties if you do anything

[Got-Busa?]

Whatever you do, DO NOT spend $200+ on the billet stacks....

Put that money towards a nitrous kit if you want more power...

[MikeSomething]

Originally Posted by mattstang

dont waste your money on the billets. go with the rubber oem shorties if you do anything

Thanks, what I'm tryin to find out, is if it's worth going from stock 2 small, and 2 big stacks... to just 4 small stacks which I can purchase for cheap or just not touching it?

[mattstang]

Originally Posted by MikeSomething

Thanks, what I'm tryin to find out, is if it's worth going from stock 2 small, and 2 big stacks... to just 4 small stacks?

i havent tested it. if your consistent try it at the track.