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Old 03-28-2011, 01:50 PM   #1
86rustanggt
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Question screw vs roots ProMod

I am a huge fan of blower ProMod cars and I often hear guys talk about "screw" blowers when talking about a kobelco 14-71 or some other type. I thought those superchargers were actually roots type? And they came in either standard or high helix types? Calling them a "screw" is that slang like calling all superchargers "blowers?" Or am I wrong and they are actually twin screw? If it depends on the guy can you tell me why you would personally or have personally chosen one over the other? And to answer the question ahead of time, "Yes I have already hit the newb thread" I'm Just trying to get more information on the cars that seem to take up a big amount of real estate in my wet dreams!!

Thanks for the info in advance.
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Old 03-28-2011, 02:05 PM   #2
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Default Re: screw vs roots ProMod

you are correct. the only true "screw" is a PSI "C" or "D" rotor. The whipple is sometimes called a screw, and though it is closer to being a screw than the roots that you mentioned, it is not a true screw.
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Old 03-28-2011, 02:14 PM   #3
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Default Re: screw vs roots ProMod

The whipple is a screw as well as the psi b which is for gas applications.
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Old 03-28-2011, 02:45 PM   #4
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Default Re: screw vs roots ProMod

I still dont think you guys answered his question. I think he is confused as to the difference in a Roots and Screw blower.

Yes there is a difference in them. A roots typically has 2 "shafts" with 2 or three lobes on them and when spun they mesh, A screw has 2 "shafts" that look like two screws that mesh.
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Old 03-28-2011, 02:52 PM   #5
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Default Re: screw vs roots ProMod

I understand the difference in the internals, I just want to know if they are using a true screw blower or if they are using a roots blower and the name "screw" is just being used? Kinda like when a guy with a centrifigal super charger still calls it a blower?
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Old 03-28-2011, 03:38 PM   #6
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Default Re: screw vs roots ProMod

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Originally Posted by 86rustanggt View Post
I understand the difference in the internals, I just want to know if they are using a true screw blower or if they are using a roots blower and the name "screw" is just being used? Kinda like when a guy with a centrifigal super charger still calls it a blower?
It's either a ROOTS or a SCREW!! Someone that called a 14/71 a screw didn't know what they were looking at.
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Old 03-28-2011, 03:46 PM   #7
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Default Re: screw vs roots ProMod

Unless it was a superman case with prototype screw rotors inside.
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Old 03-28-2011, 05:19 PM   #8
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Default Re: screw vs roots ProMod

Alrighty that answers that.... so why would you take one over the other? I thought a roots makes alot of heat?
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Old 03-28-2011, 05:58 PM   #9
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Default Re: screw vs roots ProMod

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Alrighty that answers that.... so why would you take one over the other? I thought a roots makes alot of heat?
they do, however the tried and true 14-71 is allowed in almost all classes, pro-mod, top fuel, most quick 8 / quick 16 ect. the screw, PSI & Whipple are outlawed in almost every class other than ADRL and NHRA TAFC / TAD.

the screws make a good deal more power than the roots superchargers, but if the rules say you cant run em, it dont matter!

for the big bad ass blowers the PSI Screw is the king of the hill!
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Old 03-28-2011, 08:43 PM   #10
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Default Re: screw vs roots ProMod

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Originally Posted by crystal_freak View Post
they do, however the tried and true 14-71 is allowed in almost all classes, pro-mod, top fuel, most quick 8 / quick 16 ect. the screw, PSI & Whipple are outlawed in almost every class other than ADRL and NHRA TAFC / TAD.

the screws make a good deal more power than the roots superchargers, but if the rules say you cant run em, it dont matter!

for the big bad ass blowers the PSI Screw is the king of the hill!
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Old 03-28-2011, 10:46 PM   #11
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Default Re: screw vs roots ProMod

Why have they ruled for the roots over the screw blowers anyway, cost, safety?
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Old 03-28-2011, 11:27 PM   #12
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Default Re: screw vs roots ProMod

ok speaking of that could you imagine how quick and fast a top fuel dragster would run with a screw blower on it. << a screw blower on a fuel motor.
a screw blower is much more efficent if that helps
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Old 03-28-2011, 11:39 PM   #13
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Default Re: screw vs roots ProMod

well now i know the people i hear talking about a "screw" 14-71 blower are using it as slang. Thanks
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Old 03-28-2011, 11:55 PM   #14
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Default Re: screw vs roots ProMod

Its simple if you had the money for a PSI /d rotor you wouldnt screw with a roots.that help ya....
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Old 03-29-2011, 12:05 AM   #15
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Default Re: screw vs roots ProMod

Quote:
Originally Posted by crystal_freak View Post
for the big bad ass blowers the PSI Screw is the king of the hill!
Bingo! Outlawed because they would rule the roost.
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