Velocity Stacks

[Marc Salvisberg]

I know this is an this is an old post but wanted to throw my two cents worth in. I tried the Factory Pro velocity stacks and they were a waste of money. You are better off using 4 short OEM stacks and they only cost a couple of bucks each. By using the Factory Pro's it actually cost me HP.
With Factory Pro's

Short Stock OEM's

Seems to have gained SIX(!) horsepower with short Suz stacks......

Other people can't tell the difference and other tuners say that there's little or no difference on a Gen 2.

Oh! This is a Gen 2 Hayabusa forum! He's got a Gen 1 Busa.. It IS an old post.

Still - on a Gen 1, I've never personally ever gotten such dismal results with the Gen 1 Factory Pro stacks or such stellar results from 4 short Suzuki stacks.

On a Gen 1 (not Gen 2), the short Suz 1000 stacks are generally worth about 2 on top and lose about 2 in the low and mid, stock engine and the generic 1397 / Yosh cam setup. Pretty consistently (as in 100% of Gen 1's I've tested with stock vs 4 short stacks). Not 6.

Poor test procedures? Poor tuning? Weird bike? I'm sure it wasn't intentional - but those results are curious and not what I or Schnitz have seen in a Gen 2.
.................
Those of you who know me already know that I am not a big fan of dynojet dyno style "whack the throttle on in 4th gear" inertia dynos that only use residual oxygen (so-called AFR) for testing and tuning purposes.

For years, they've told people that a 6-7 second, low rpm to the rev limiter run is "enough load" on the engine and that tuning to some "AFR" value is "good enough" for a street guy. But it's not good enough.

The above charts don't provide a realistic amount of engine loading OR provide 4 gas EGA information to help determine why they got such diverse results - leaving it a Gen 1 related mystery.

Marc

 

[dmrowe]

Marc,
The results on my Gen1 are in keeping with what I was told to expect and what others have gotten using the same mods. What the issue is with the velocity stacks I won't go into since I am not an engineer but I posted these results over 4 yrs. ago so this conversation is more than a little dated. I do however trust the work that Lee's does and the results that are depicted on the charts. I know that you claim to produce your own dyno but it is not very previlant in the market place so we have to work with the tools at hand. I read all the information that you provided me after our intial phone conversations back in '06 and personally most of it went right over my head since I am not an engineer, to me the proof is where the rubber meets the road.

 

[Marc Salvisberg]

deleted by author

 

[Marc Salvisberg]

There seem to be a common thread regarding the Gen 1 Busa stacks - guys who slap them on, no tuning and ride, are usually happy.
They get better low, mid and especially upper mid - and maybe a bit of peak, too.
They probably don't rev their bikes past the redline and probably only hit the rev limiter if they miss a gear.
1/4 mile performance usually improves (hint - shift at about 10,300)

Then there's other guys - They install the stacks and get their bikes tuned an a real eddy current brake dyno, to Best Power (not to an AFR) and they are, well, I've never heard of anybody who wasn't happy.

Then there's the guys who get the stacks and take their bikes down to the local "performance center" place and proceed to run the stacks on an inertia dyno and tune it to an AFR again. They are the ones who, apparently, can have less than optimal results.

What the common thread?
None.
But - do nothing and the bike runs stronger, tune to Best Power on a brake dyno and the bike runs stronger.
Run the bike on an inertia dyno and tune it to an AFR and the bike makes less power.

In any of the inertia dyno runs that I've been sent of a Gen 1 Busa with stock cam timing, this is the most manic/depressive chart ever - The "+2 hp" short stacks make 6 hp and the FP stacks, which at worst, should have made around stock power at peak, are down 6.

We will probably never know the whole story as to why this is the worst of the worst dyno charts and the best of the best for short Suz stack - Sure there's more to tell that only an engineer would understand. But I half expect the same charts to show up on a gsxr600 forum......

Good thing that Jordan Racing understands - They had the strongest Superbikes at Daytona, and use a real EC997 brake dyno and guess who's stacks.....

Best regards,

Marc

 

[busa_black]

I have a Gen I, and wouldn't mind buying a set if I could get 4-6hp. My local "performance center" place uses a Dynojet dyno, and I'm not an enthusiast to the point that I would ride/travel to find real eddy current brake dyno. I have a full exhaust, small box, and a race air filter. I spent the summer looking for a reason to spend the money, but I couldn't find one.

 

[m_ridgeway]

i called a dealer to ask to buy these and they talked me out of it and into the gsxr1k stacks.....

 

[m_ridgeway]

HEALTHY +3 to +5 True HP gain at 9000 rpm when measured under a real load on a stock engine. We did not change fuel injection tuning.

And! Bonus!
The High Velocity Superflares bring back that sweet, but discrete, high rpm intake "howl" that a well tuned engine should have!

so if your shifting shorter than everone else the super sweet bonus is really making you slower....

so whats the typical trap or et gains on these.

 

[m_ridgeway]

"Math check"! <wink!>

3-4 HP for Factory Pro stacks that cost $250 at full price and take 30-45 minutes to install by the owner.

Last I looked, Yosh or Megacycle drop-in cams were $700 - $800 a set and were worth 6 to 8 HP (average ~7).
Installation takes 3-4 shop hours of labor

Breakdown:

Factory Pro stacks as tested at HFD1 in Georgia, $250/3.5 hp
about $67 per HP
Most owner's can self install.

Cams:
Yosh or Megacycle, dropin type, $750 average cost / average 7 hp
about $105 per HP
Plus - most owners will pay a shop 3-5 hours to install and degree.

Looks more like the cams aren't worth it?

 

[Marc Salvisberg]

I think you mean that the math is too easy?

 

[m_ridgeway]

I think you mean that the math is too easy?

Performance & Perfection: Miracle Mod

itll be my next mod after this one

 

[Marc Salvisberg]

so if your shifting shorter than everyone else the super sweet bonus is really making you slower....
so whats the typical trap or et gains on these.

Shifting:
The horsepower curve looks like a hill.
There is a slope on the left and a slope on the right - with a peak in the middle. We don't really care about the peak height, because we want to be the highest over a 1500 - 1700 rpm gear spread - which is on the left and right sides of the peak -
What we want is average horsepower over that about 1700 rpm.

Here's how you roughly figure out about where you SHOULD be shifting.
Go every 100 rpm.
Add up the power, over 1700 rpm. Get a total, divide it by 17.
That's you AVERAGE hp over those 1700 rpm
Now move up 100 rpm and do the 17 thing again.
Go up and down until you find the highest AVERAGE over that 1700 rpm -

That's the rpm range that you want to use - and it's not much past the redline - if at all.

The other way to do it is to try bouncing the bike off the rev limit in the 1/4, then try 100 rpm lower and 100 rpm lower and so on. You'll be slow, then quicker, then quicker, etc then you'll finally start to get slower again, go back up 100 rpm.

ET:
Do I LOOK like a drag racer? (no) :-)
I just gave you .2 above.

If one insists on bouncing the bike off the rev limit with our stacks, you'll go slower.
The stacks boost the power on the way "up to" the power peak - and not where the power drops off - after the power peak. You NEED to shift earlier - and you'll end up with better AVERAGE power.

You bought the short stacks - They don't really help the power (probably hurt the low and mid a couple hp) on the way up to the power peak, but they don't drop off as much as stock or ours AFTER the power peak - so instead of shifting at 10.3 or so, you'll probably shift at 10.7 or so.

I think that our average hp is better than the short stacks (measured on a real brake dyno).

Any of that make sense?

Marc

 

[m_ridgeway]

so these have never been tested on a street/strip bike.

did you ever respond to professors offer to test them?

 

[BIG GUY]

What is the actual job of a velocity stack? Do they help get the air into the motor faster?

 

[Marc Salvisberg]

i called a dealer to ask to buy these and they talked me out of it and into the gsxr1k stacks.....

From a dealer's standpoint - they are inexpensive, make a difference and easy to order from Suzuki.
If you don't like the loss of lowend, it's ok, they were only about $60.
:-)

 

[m_ridgeway]

Performance & Perfection: Miracle Mod

itll be my next mod after this one

Looks like sticky backed insulation. No miracle.
esp for THREE HUNERT DOLLARS!
A lot of bikes have it on their airboxes.
Marc

thanks for the info...

its snake oil just like 3-5hp from any velocity stack.

it was in sarcasm

 

[Marc Salvisberg]

S88t! I wasn't kidding - go to the store and get $10 worth of that mylar bubble wrap stuff and tape it around your air box and see - I'll bet there'll be some difference.
It's mostly the lower airbox that gets heated -
We used to do that with stick on heat shield on our racebikes.

 

[m_ridgeway]

so no results on a drag bike with these?

 

[Marc Salvisberg]

thanks for the info...

its snake oil just like 3-5hp from any velocity stack.

it was in sarcasm

That's pretty funny.
It was funnier before you edited it. <wink!>

But that information is probably from the same sort of dyno that said short Suzuki stacks were worth 6 hp.
Otherwise you wouldn't think that you couldn't manage to get 3-5 hp on something.

Come on now -
We've made stacks for World Supersport 600 teams, stacks that have gone on ZX14 and gsxr1000 land speed record holders, World Endurance Teams, Jordan Suzuki, Vesrah Suzuki, Motorcyclist and Sportrider project bikes, Erion Honda bikes, and loads of other teams and bikes - there was even a set on Doug Chandler's Zx10 streetbike. Even Ryan Schnitz tested them.

If all these guys think that they work, how am I supposed to take some guy's funky dynojet charts done at a local shop? :-)

Marc

 

[Marc Salvisberg]

What is the actual job of a velocity stack? Do they help get the air into the motor faster?

General V Stack functions: Wikipedia
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A different point of view:
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In an engine with a single throttle body per cylinder, the stack has to be the right length to get the pressure waves in sync with the intake valve opening and closing for ram effect -

Thanks -
M

 

[m_ridgeway]

That's pretty funny.
It was funnier before you edited it. <wink!>

But that information is probably from the same sort of dyno that said short Suzuki stacks were worth 6 hp.
Otherwise you wouldn't think that you couldn't manage to get 3-5 hp on something.

Come on now -
We've made stacks for World Supersport 600 teams, stacks that have gone on ZX14 and gsxr1000 land speed record holders, World Endurance Teams, Jordan Suzuki, Vesrah Suzuki, Motorcyclist and Sportrider project bikes, Erion Honda bikes, and loads of other teams and bikes - there was even a set on Doug Chandler's Zx10 streetbike. Even Ryan Schnitz tested them.

If all these guys think that they work, how am I supposed to take some guy's funky dynojet charts done at a local shop? :-)

Marc

so out of all those people none of them gave you a drag test result?

the edit i did was to go by your site. i was looking at another one of your adds and realized it wasnt your site. it said 6-8 hp on a stock gen 2.