The Velocity Stack Guide

[dmrowe]

The dyno is not the best device to measure.. it does make the prettiest paper to look at however.. In theory yes your program works, but in the real world it comes up short..

sure you can tune and measure all you want... the real test is on the track..

you can not drag race on a dyno.. dont care what anyone says, I have seen more than one absolute dyno killer motor get pasted by an "also ran" motor..

sure you can optimize your combo on the dyno, but when it comes to the track? I have never seen a motor or combination perform its best until it has been tweaked on the track.. not saying you can not get it close..

Then you can then go back on the dyno and see where your tuning moved the power curve.. Vehicle and engine acceleration just can not be measured accurately in a static environment..

let me put it to you like this..

IF and that is a big IF the dyno was such a panacea of performance tuning... dont you think you would see the heavy hitter drag race teams with them at the track? really... they could make 4 or 5 pulls, tune the motor for the air and head right for eliminations...

They dont, because it doesnt work.. (and I for one am glad, it would take the fun out of racing)

and before anyone says "it is cost prohibitive" ... take a stroll through the pits at an NHRA national event.. you have privateer guys with a $20,000-$250,000 race vehicle with $500,000 truck and trailer just to drag it around.. These guys are dead serious about winning, if it worked, they would have it so fast your head would spin...

Yes, I agree that the dyno gives you a good starting point to do your tweeking to fine tune. It is a far, far better tool to use than when we just went out ran the bike, pulled spark plugs and checked them and the pipes for color...and quite often we burned holes in pistons. The dyno chart is much more than pretty paper...google NHRA & dyno tune and see how many hits you get. The guy that sold me the velocity stacks said he didn't need to put them on a flow bench to see how well they worked, he did it all by mathmatical formula and I found out how well that worked out. Flow benches and dyno's are tools at our disposal to help us get the best possible tune without costing us an engine and give us a starting point from which to measure improvement. Now that is just humble opinion as a layman who has spent his money and learned from the experience.

 

[ogre]

posting from the first page, and i don't know if this has been mentioned yet, but if you're going to do four stacks the same length, you should unify the fuel and ignition maps.

 

[Mr Bogus]

a flow bench wont work for doing velocity stacks by the very nature of how they (v.stacks) work..

the mathematics part? will get you very close.. our "engineering" guy was like that, knew the formulas for that type of stuff.. We could give him port volumes and lengths, he could give us "optimal" flow numbers to work towards.. It was up to us to figure out how to keep fuel distributed at the same time

 

[Got-Busa?]

The dyno is not the best device to measure.. it does make the prettiest paper to look at however.. In theory yes your program works, but in the real world it comes up short..

sure you can tune and measure all you want... the real test is on the track..
.

You didn't get the memo, a $55k dyno is the latest thing for going fast...

Everyone should buy one...

 

[Highway]

Has any one tried all 4 long stacks???

 

[cwalker2]

As a former mechanic for an NHRA prostock bike team, I can tell you every engine goes on the dyno. And no, not the toy Dynojet dynos, they don't collect enough data.

We would develop each engine and as soon as we had one with better power, we made the other two match it, then developed again. As soon as we found another couple of horses, we matched the other two and started again. You didn't haul a dyno to the track because the dyno was for development and the track was for racing.

It was similar, though not as intensive when I crewed for an AMA pro-twins team.

 

[mucky]

Has any one tried all 4 long stacks???

im new to all this and was wondering the same thing. would it increase torque or hurt it

 

[BA BUSA]

im new to all this and was wondering the same thing. would it increase torque or hurt it

ALL long stacks help mid range torque...but they hurt peak HP too

 

[mucky]

thanks for the help. I think i'm going to leave it stock, the motor is in a minirail and I didnt know if it would help me with the low end without changing sprockets

 

[California Kid]

DATA LOG .

Bill

 

[Liltroy]

were both of these dyno's done on the same day? if not...then they dont matter anyway. And if so, why didnt they overlap all four on the same graph for comparison?

 

[busa_black]

I was interested in stacks, but I still need my PC III mapped. In my case the stacks don't pass the price vs. performance test..

 

[ogre]

if you're going to run 4 oem shorties, you should unify the fuel maps in ecuedit.