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Discussion Starter #1 (Edited)
One of my soldiers here is a fellow rider; he has an '07 600rr, I have an '06 1000rr. He's fired up to buy these things called "velocity stacks" that supposedly give "+2 hp across the entire band" which sounds like a load of crap to me. the problem is that NO ONE seems to know what they actually are or what they actually do.

what the heck are they?
 

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one of my soldiers here is a fellow rider, his is a 2007 600RR, mine a 2006 1000rr. he's fired up to buy these things called "velocity stacks" that supposedly give "+2 hp across the entire band" which sounds like a load of crap to me. the problem is that NO ONE seems to know what they actually are or what they actually do.

what the heck are they?
hey hgate73, here are some pics i pulled up obviously these are a little to the extreme side of things but they are located underneath your airbox and ontop of the intake ports, think of them as a intake manifold on a v8 style engine, a friend of mine picked up a set for his 05 R1 and it made a huge differance, the aftermarket ones were about a half inch taller and polished alluminum as opposed to the factory plastic ones, the air flow entering the head was so much smoother it really helped the air fuel mixture and i dont know for sure but i think he picked up a tenth on his quarter mile time as well
 

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ya exactly, i dont know all the ins and outs of bikes yet but from what i have seen from friends bikes and talking to other guys who have bought them they do get the 2hp jump if not more depending on the map, i think the most i heard was 4 or 5 not sure but there is a shop in fargo that has a dyno and they let us go and tune our selves so they do make a differance i would suggest getting some, i can get a web site for ya if you want
 

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The only thing I would add is there has been a lot of R & D gone into the airflow design inside the airbox on the bikes you mention. If you notice inside the airbox you'll see very similar shapes in plastic already in place.

The theory behind the shape is to speed the air rushing in as much as possible to charge the cylinders to the max since the intake valve is open for such a short time. That what blowers and turbos do. Problem is at some point there is a trade off that in a effort to speed the air up by going through this shape, you can actually end up restricting the air flow.

You could end up with improving mid range power and suffering at the top RPM because of a restriction. Only a dyno I guess will tell.
 

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One of my soldiers here is a fellow rider; he has an '07 600rr, I have an '06 1000rr. He's fired up to buy these things called "velocity stacks" that supposedly give "+2 hp across the entire band" which sounds like a load of crap to me. the problem is that NO ONE seems to know what they actually are or what they actually do.

what the heck are they?
Modern sportsbikes all come with factory velocity stacks now anyway. They've been designed to compromise between outright topend power (which can be a pain on the road) and strong midrange which is wanted by the vast majority of potential riders.
Aftermarket v-stacks tend to optimise the power more toward the topend I think.
Regardless, the difference they make is not going to be significant for road use. Most people probably get more mileage out of telling people they've got v-stacks than any benefit they might get from actually having them.
 

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Modern sportsbikes all come with factory velocity stacks now anyway. They've been designed to compromise between outright topend power (which can be a pain on the road) and strong midrange which is wanted by the vast majority of potential riders.
Aftermarket v-stacks tend to optimise the power more toward the topend I think.
Regardless, the difference they make is not going to be significant for road use. Most people probably get more mileage out of telling people they've got v-stacks than any benefit they might get from actually having them.
that would make sense why my friends 05 r1 gained time on his et due to the fact you spend most of the time in the top range of the rpms, im into drag racing as well are my friends i never thought to ask about midrange, because im not sure if they are dealing with just top end, or all the way up the powerband
 

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that would make sense why my friends 05 r1 gained time on his et due to the fact you spend most of the time in the top range of the rpms, im into drag racing as well are my friends i never thought to ask about midrange, because im not sure if they are dealing with just top end, or all the way up the powerband
Unless you are able to consitantly run times within 0.1 of a second already it's going to be very difficult to put 0.1 second improvement down to the v-stacks.
 

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he ran 10.1 all season then had a similar discussion as this one with a another rider/racer who knows more than the 2 of us combined and he said its worth a shot so the stacks were ordered, put on the bike, went to the dyno, then the track and he ran 10 flat all day with a personal best of 9.96, but i think the bike is in for the worst he wants to do a motor swap to a gsxr 1000, here is a pic of how the bike sits right now
 

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Discussion Starter #10
this is interesting reading...thanks for the information and thoughts.

@drama, is your buddies swingarm extended?
 

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this is interesting reading...thanks for the information and thoughts.

@drama, is your buddies swingarm extended?
ya with the way the drag races are set up around fargo there are 2 classes one with stock wheel base and one with extended wheel base, so there are a couple guys i know depending on where we are going to race that perticular weekend will either just run extensions or swap out the swing arm all together for a streched swing arm (term could be wrong) its just another way to either win or keep from being made look like a fool, ill post up some pics later but another buddy of mine just slapped a turbo on his 08 gsxr 1000, it looks mean
 

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after reading that i never really answered your question but in that picture there are just 6" extensions on there its not a full swingarm, my bad
 

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everything that i have read/ including numerous dyno chart comparisons that i have seen. The most they will do is keep you at stock power, but they generally drop you 2 hp across the ban. Keep in mind also they did a lot of tuning and were actually trying to extract the power on the dyno. Everyone else who has ever commented on it(that I read) said they felt no difference at all. I figure either way a 2 hp loss or gain isn't really gonna be noticeable. The only results i have ever looked up have been for honda's. I personally "think" the design of the airbox, and the runners leading into the airbox may be more of a restriction point than the intake runners(or velocity stacks as you call them) so upgrading the stacks without finding a way to create more flow into the airbox itself may be futile. This is only a thought though, i am not sure. In fact when i am workin on my bike before spring i may try to experiment with this. But after looking at the runners into the airbox, I think you would see what I mean. I met a really kool guy with a dyno that works as a ducati dealer. I am trying to get a 1198s this spring, so maybe i will be able to work out a deal with some free or cheap dyno time included for both bikes. If I find anything out I will post it for ya though.
 

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The velocity stacks add to the tuned length of the intake tract. The longer the tract, the lower the rpm the tract is tuned to. In a perfect world, the tract length would be continuously changed with rpm to optimize the sonic tuning of the intake port.

Motorcycles cover such a great RPM range, that it is hard to reach a compromise that does much more than bump out put over a few hundred RPM. That is until they came out with stacks that pop up at a certain RPM. They are on Yamaha's with FI. That would extend the RPM range that the boost effect covered.
 

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That is until they came out with stacks that pop up at a certain RPM. They are on Yamaha's with FI.
You mean Yamahas have variable stacks already?
 

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Discussion Starter #19
So are they in any way related to honda's vtec system, where it changes the valve timing when you hit a certain rpm?
 

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So are they in any way related to honda's vtec system, where it changes the valve timing when you hit a certain rpm?
Related in what way?
V-TEC is a hydraulic pin that moves to open up the valve clearance on two valves in each cylinder so it runs as a two-valve engine under 7000RPM (from memory).
 
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