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Author
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Topic: Centrifugal or Roots?
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Mooney
Gearhead Posts: 1580
From: Marietta, Ga
Registered: Oct 2003
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posted 10-04-2004 08:04 PM
   
Well thats basically it, the question that is. Just thinkin' here, thinkin about the future and beyond. But honestly, was going to get a set of heads but my G/F's cousin was hit by a car which drastically changed income situations. Was one day away from purchasing some RPM's. But hes turning out OK at the moment so I can keep dreamin'!
But I was lookin' and saw that Holley has a roots type 177 s/charger for 2100 dollars. And I thought hmm, set of heads for 1300 or a supercharger... Well I figured get the expensive stuff out of the way first. (Still dreamin' here, also is this a good sequence?) But I"m confused, I know centrifugals run a bit more price wise, but what are the pros and cons of both? Which would be best for my setup?
I've got an 87 HO
F303 Cam
Intake Duration 050 inch Lift 226
Exhaust Duration 050 inch Lift 226
Advertised Intake Duration 288
Advertised Exhaust Duration 288
Intake Valve Lift 0.512
Exhaust Valve Lift 0.512
Lobe Separation (degrees) 109RPM Intake w/ 600 cfm performer carb
And Longtube headers
T-5
And I've got 3.20's in the rear at the moment but plan on either 3.73's or 4.10's I've got about half of the price of a roots charger saved up. But don't want to jump in head over heels thats why I say I'm still dreamin'.
So if anyone could give me advice vs tips on which would be better for this setup that'd be great! Or just tell me I've lost my mind and go worry about my rent and buy my g/f a diamond ring or something!
Either way, any tips would be great!
Thanks,
Luke
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MrWesson22
Gearhead Posts: 1280
From: Dacula, GA
Registered: Sep 2000
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posted 10-05-2004 12:24 AM
It depends on you. In general, roots and positive displacement blowers make more lowend/midrange power but run out of breath up top and aren't quite as efficient. Centrifugals don't make a lot of boost until high rpms but usually make higher peak numbers and run more efficiently (cooler intake charges as well). Do you want it to kick you in the pants right off idle, or do you want that insane topend pull?
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Neal 69 Gulfstream Aqua Grande
351C/4sp
https://mustangsandmore.com/ubb/MrWesson22.html 99 GT 5 sp coupe
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Dubz
Gearhead Posts: 1718
From: Manitoba Canada
Registered: Oct 2002
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posted 10-05-2004 02:01 AM
The roots will be better with a carbed setup
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Mooney
Gearhead Posts: 1580
From: Marietta, Ga
Registered: Oct 2003
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posted 10-05-2004 06:01 AM
Well, I'd have to say off the line. I don't do much highway driving. So I don't feel as if I need a high top end. That and somewhere around 80-90 mph I get a nasty shimmy anywho. Does anyone have any preferences on brands of roots blowers? Which is better over another?
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indyphil
Gearhead Posts: 2398
From: Senoia, G.A. USA
Registered: Jul 2002
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posted 10-05-2004 12:55 PM
There are many types of positive displacement pumps. I think that somewhere someone is developing Lysholm screw type blowers which are more efficient.I copied and pasted this from another site
Roots type blowers use interlocking identical lobes that pushes air into the intake manifold where it is compressed, or "boosted". Once positive manifold pressure is achieved, it can cause some blow-back into the compressor.
Centrifugal type blowers are virtually belt driven turbochargers. They need revs to spool up and deliver their boost higher in the engine rev range. Screw type blowers compress air in the blower housing itself, as well as in the intake manifold. They use male / female screw shafts that never touch but have extremely tight tolerances, minimizing or eliminating any blow-back into the supercharger housing after boost is achieved. Screw type blowers have greater adiabatic and volumetric efficiency over the entire operating rev range than do Roots or Centrifugal blowers.
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'68 coupe, '66 289 C code
engine, edel 600cfm carb, performer intake, dual exhaust http://www.geocities.com/ottouk_77/68mustang.htm
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