Gixxer600
member
Reged: 20/04/2007
Posts: 121
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been looking at getting some velocity stacks. but i am just wondering how they work! does anyone know, if so please explain?
thanks
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BigHam
old hand
Reged: 12/11/2006
Posts: 1096
Loc: Letchworth, UK
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They are replacement inlet trumpets. They are a different shape to OE ones to boost top end and midrange at the expense of bottom end.
They are usually made from metal, unlike the plastic OE ones.
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http://www.myspace.com/big_ham_1988
Where there's a will and Gaffa Tape there's a way!
Edited by BigHam (16/06/2008 12:34)
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Gixxer600
member
Reged: 20/04/2007
Posts: 121
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yea, i fitted some to my mates r6, but i've just never understood how they work n whether an extra few bhp is worth the money. like how do they boost midrange?
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BigHam
old hand
Reged: 12/11/2006
Posts: 1096
Loc: Letchworth, UK
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They have a different shape to the OE ones. Short velocity stacks are better for top end, whereas long ones are better for bottom end. The after market ones are simply shorter and/or wider in order to help the engine breathe better at high revs, it's a compromise because it now won't breathe as well at lower rpms if that makes sense?
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http://www.myspace.com/big_ham_1988
Where there's a will and Gaffa Tape there's a way!
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morepower
enthusiast
Reged: 21/12/2006
Posts: 276
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Most 4 cylinder velocity stack kits have two different length stacks. One pair longer than the other. Make sure you put them in the correct position as I have seen a bike lose 7BHP just putting them in the wrong positions. Factory Pro ones do work well and will give gains but the gains are often smaller than claimed but if you do more to the bike like add a full system or have a full tune with skimmed cylinder head the gains are then worth while as they seem to work better the more you do to the engine..
I have some fitted to our little GSXR600K6 and they work well and we are now at 120BHP at the wheel after doing a bit more work than a pipe and power commander.
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I'm not competitive, I just like a good veiw!
Edited by morepower (17/06/2008 10:15)
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chappers
Carpal \'Tunnel
Reged: 31/12/2006
Posts: 5115
Loc: Mind your own business
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I was about to sit down and start to try to write something down regarding resonance and the venturi effect but don't really fully understand it eough myself to explain it but this article should help BTW intake runners are Velocity stacks.
If it helps I do understand that tuned length refers to resonance waves encountered in both exhaust and intake, I think of it as making music as you would in a church Organ each pipe resonates at a set fequency and the taper on the stack will help to speed the gases up.
http://auto.howstuffworks.com/question517.htm
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If you Believe you will achieve,init.
Dizzee Rascal 2008.
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Biggles
Pooh-Bah
Reged: 05/05/2007
Posts: 2135
Loc: I am over here!
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Quote:
They are usually made from metal, unlike the plastic OE ones.
Plus apparently. The plastic ones can distort and spoil the theoretical flow they were designed to enhance.
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 I refuse to be a member of any Forum that would have me as a member
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1DOG
member
Reged: 21/09/2008
Posts: 166
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In addition to the correct advice above your PC will also need to be remaped,I looked into fitting these a little while ago but as i do mostly short circuit trackdays they offered little benefit to me as i dont need anymore top end and wasnt keen on losing low down grunt.
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