Velocity stack differences for 5th, 6th, and 8th gens

[oldred95]

Does anyone know the dimensions of the velocity stacks for the 5th, 6th, and 8th generation VFR's and whether or not they will interchange?  After looking at the parts catalog, the 5th gen stacks, while no longer available from Honda, are all four the same.  On the 6th gen there are two longer stacks for the rear two cylinders and two shorter stacks for the front two.  On the 8th gen all four stacks are the same part number and look similar to the short stacks of the 5th gen of 6th gen.  The air cleaner boxes all look very similar in design and the 6th and 8th gen air filters show to interchange.  I've got a Piper Cross air filter waiting to be installed and I was wanting to do something with the velocity stacks to make the most of the freer flowing air filter if there is any proven velocity stack upgrades for the 6th gen.

[keef]

6th and 5th gen are interchangeable. I bought 4x 6th gen short stacks for my 5th gen. 

6th gen at box lid fits the 5th gen base.

5th and 6th gen bases are slightly different as the sensors/hoses are in different locations.

 

no idea about the 8th.

[oldred95]

Are the 6th gen short stacks shorter than the 5th gen stacks?  What about the inside diameter?  What was the end result once installed on the bike?

[keef]

yes, shorter, and they are a drop in fit. I am assuming ID is the same. My vfr is used only slightly more than the phantoms; I haven't ridden it in anger yet to compare it.

 

I will end up with either dual stacks, 2 super short ally ones and 2 short 6th gen ones, or a combination.

 

 

[squirrelman]

48 minutes ago, keef said:

yes, shorter, and they are a drop in fit. I am assuming ID is the same. My vfr is used only slightly more than the phantoms; I haven't ridden it in anger yet to compare it.

 

I will end up with either dual stacks, 2 super short ally ones and 2 short 6th gen ones, or a combination.

 

 

 

 

This needs road and dyno testing. Tune to boost any rpm range where it needs it most, based upon dyno curves.    

 

Computer and math could work this out exactly, with charts and curves. 

[Mohawk]

Squirrelman, Err if you look at my Yoshi Stacks & big airbox mod threads, you will see the numbers. The Big Airbox mod, basically moving the filter to the lid of the airbox gained 5hp, the short stacks I made, which are cut down stock ones that are 30mm shorter than standard allowed the engine to hold onto its breathing for longer, as it retunes the intake pulse for a higher rpm.  My bike is heavily modified, but these simple changes should have an effect on a stock bike. With these added my bike accidentally pulled a 4th gear wheelie off a small bump in the road at 100mph under hard acceleration !

 

YNMV  (where N=Numbers)

[keef]

i didn't do no numbers.

I'll just ride mohawks coat tails.

[gig]

Mohawk,

Do you have numbers showing the air box mod alone with shorter stacks gave you 5hp tuned?

Where or did it sacrifice any low end torch with the shorter stacks? 

 

Keef,

Do we know how much shorter the short 6th gen stacks are compared to the 5th gen stacks?

 

Thx