Short stacks?

[MN72Busa]

So can someone explain this whole short stack thing to me? I have 2 airboxes, and in theory I could use all short stacks. What is the gain, what is the loss.

Are the short stacks in the center or outer stacks? Is it better to use the short stacks in a moded airbox or use it in the stock box?

Can someone break it down in simple terms for me, and why I should or shouldnt do it?

 

[Devil Dog]

yeah..what he said!!!!!

 

[Charlesbusa]

I can't remember which way it is, but stock is 2 short and 2 long. You can make all 4 short or all 4 long. One way gives you more power on the top end(rpms) and the other way gives you more power on the low end(rpms). Kinda like gearing changes. I could be wrong, that's just what I remember last time I saw this topic.
Hope it helps

 

[Mr Brown]

Having all 4 short stacks supposedly gives more top end power when used with an airbox mod. I've tried it, I couldn't tell any difference from 2 and 2. I think it's one of those things that makes such a small difference that unless you're already getting everything else 100% perfect, it don't matter. Check out sh.org, or psychobike for more discussion on the topic.

 

[Bugsy]

the rubber stacks inside your airbox.
going all short changes the runner length of intake.

stock is mixed 2 short and 2 mixed
all short gives more peak power with a loss of low-end
all longs gives more low-end with loss of high rpm power

most who have tried all shorts on stock engines go back to stock.

 

[BATTMAN]

Only use all short if you are spraying on stock engine, have cams, or big bore.

 

[cache]

Having all 4 short stacks supposedly gives more top end power when used with an airbox mod. I've tried it, I couldn't tell any difference from 2 and 2. I think it's one of those things that makes such a small difference that unless you're already getting everything else 100% perfect, it don't matter.

correct, and I didn't tell a difference other than on paper... ran quickest et's ever after going all shorts a couple months ago.

 

[MN72Busa]

Hey, thanks for explaining the whole short-stack thing to me. Would it hurt my low end torque to go all short stacks? I have the parts, and can do it, just dont wanna drop gobs of torque. Anyone have any dyno sheets on all shortstacks on moded box, vs. stock box, stock stacks on a Busa with full exhaust?

 

[frisbee]

So short is better for top speed right?

 

[huntn4heatrs]

So short is better for top speed right?

no, all shorts for cams and/or head upgrades. Shorts have nothing to do with top speed.

 

[sully]

better for top end, YES. But look at a full dyno chart, i have notice that you sacrafice some mid range numbers to get the peak HP. It isn't worth the trade for me.

 

[huntn4heatrs]

better for top end, YES.  But look at a full dyno chart, i have notice that you sacrafice some mid range numbers to get the peak HP.  It isn't worth the trade for me.

He asked about top speed which the stacks would not affect but, top end(RPM's-power) will affect.

 

[mountainmotor]

Can someone break it down in simple terms for me, and why I should or shouldnt do it?

When the 2001 GSXR 1k came out , besides using a stepper motor the throttle bodies and head were the same as on the 750 . The only difference was , and even though the same ( SRAD) intake and pressurized airbox system was used , four 5 x 15mm slots was built into the base of each velocity stack used in the 1k engine. The slots reduce intake pulses created by the larger displacement cylinders to help smooth mid-range power delivery .

I can't prove it but I think the odd and extra long design of the two inner Busa stacks are to stop the other intake pulses from jacking with each other down low and in the middle from the additional displacement.

I myself would use the two shorter stacks only with modified airbox , rephased cams " if stock " when hunting for HP along with lower gearing . If re-gear'd it will help drive though any spikes the pulses might cause at a given RPM .

Changing cams from stock and going to larger engine displacement no doubt I'd want the power increase from the low cost stack mod .