I have a theory....
uh what? blink blink loljk yea i agree with EngineerMike even though i dont know the equations to it like he does...it does make better sense. It also depends greatly on the setup and of course what you want the car for. Some would rather have lag on bottom and that rush on top. Some vice versa, some would like alittle bit of both. You always have to give alittle nothing's perfect there are too many variables that are always changing or going to change for one reason or the other. 
TECH Addict
Joined: Aug 2004
Posts: 2,866
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Great posts mike! im totally with you on that.
there will always be compromises with any setup. you just have to try and work around them, or live with them!
here are a couple of guys that are coming up with some VERY clever ways to get around spool isuses!
a BIG GT45 VNT turbo www.ls1tech.com/forums/showthread.php?t=670015
and a sequnetial setup that could have great potential https://ls1tech.com/forums/forced-induction/627907-building-sequential-turbo-system.html
enjoy
Chris.
there will always be compromises with any setup. you just have to try and work around them, or live with them!
here are a couple of guys that are coming up with some VERY clever ways to get around spool isuses!
a BIG GT45 VNT turbo www.ls1tech.com/forums/showthread.php?t=670015
and a sequnetial setup that could have great potential https://ls1tech.com/forums/forced-induction/627907-building-sequential-turbo-system.html
enjoy
Chris.
Originally Posted by otherwhitemeat
It really won't matter because you should be brake boosting anyway
Could somebody explain to me what's "brake boosting" is, or just how do you that?
Sorry, I'm just ignorant! 
Originally Posted by Boo"SS"t
Could somebody explain to me what's "brake boosting" is, or just how do you that? Sorry, I'm just ignorant!
Sorry, I'm just ignorant! 
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Joined: Nov 2001
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Originally Posted by thaigleshmk
So Twins or Single = Which is better for Roll racing?..
This post from inductionmotorsports.com , addresses both the issues in this post, (which spools faster, and which makes the most power) and touches on the physics. It is under the tech section on the left side of the screen if you want to read it from there, but I will paste it..................
.....
...
* Frequently asked tech questions/topics: Turbo choices: single or twins?
* Compression ratio and boost
* Sizing a turbo for large CID motors
* Increasing your boost range with twin wastegate solenoids
"Assuming that both setups are capable of the same amount of max power, what's better, two small turbos or one big turbo?"
Twin turbos will spool faster if the comparison is apples to apples. In other words, don't pair two 10-year-old junk yard turbos up against one brand new GT turbo and call it a fair shootout. If the twins and the single all share similar wheel technology (aerodynamics and materials) then the twins will out-spool the single. It's true that each of the twin turbos will only get half of the exhaust energy but the inertia (the resistance to a change in rpm) of the wheel is proportional to the 5th power of its diameter -- a wheel that is only 15% larger in diameter will have twice the inertia of the smaller wheel. So small changes in wheel diameter make huge changes in spool.
Second point, a single turbo is more efficient than twins because the tolerances inside the housings are roughly the same on all turbos, independent of the overall size. This means that 1/8" of clearance, for example, on a 15" housing amounts to a lower percentage of air gap (and a higher efficiency percentage) than 1/8" of clearance on a 6" housing.
Bottom line: once you get the things spooled, the single will produce more efficient boost, but the twins will make boost sooner.
Last edited by Rpm2800; Apr 26, 2007 at 05:58 PM.
Originally Posted by 02Vortech
while your rolling @ your target speed- hold the brake. and apply more gas. Apply more brake as needed to stay @ your target speed. You will begin to build boost. You can adjust how much boost you start with bye the gas pedal. You can be @ full spool BEFORE YOU EVEN START or just so you dont have any lag (0vac/0psi)
Last question.....Can you also do this on a m6 car? .....like I said, I'm just eeegnoooraaant!
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TECH Addict
Joined: Jul 2005
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Originally Posted by Rpm2800
This post from inductionmotorsports.com . . . Second point, a single turbo is more efficient than twins because the tolerances inside the housings are roughly the same on all turbos, independent of the overall size. This means that 1/8" of clearance, for example, on a 15" housing amounts to a lower percentage of air gap (and a higher efficiency percentage) than 1/8" of clearance on a 6" housing.
Bottom line: once you get the things spooled, the single will produce more efficient boost, but the twins will make boost sooner.
Bottom line: once you get the things spooled, the single will produce more efficient boost, but the twins will make boost sooner.
http://www.turbocharged.com/catalog/compmaps/fig1.html
Everything from a T61 to a T76 has peak efficiencies of 74 - 76% and they don't necessarily go up with size.
Mike
