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Supercharger Information

There are three main categories of superchargers for automotive use:

 - Centrifugal turbochargers – driven from exhaust gases.
 - Centrifugal superchargers – driven directly by the engine via a belt-drive.
 - Positive displacement pumps – such as the Roots, Twin Screw (Lysholm), and TVS (Eaton) blowers.
Roots blowers tend to be 40–50% efficient at high boost levels. Centrifugal superchargers are 70–85% efficient. Lysholm-style blowers can be nearly as efficient as their centrifugal counterparts over a narrow range of load/speed/boost, for which the system must be specifically designed.

Positive-displacement superchargers may absorb as much as a third of the total crankshaft power of the engine, and, in many applications, are less efficient than turbochargers. Desirable in applications for which engine response and power are more important than any other consideration.

CFM of Blower
60 deg std - Cu in/rev = rotor length X 27.45
High-helix -  Cu in/rev = rotor length X 31.53


Standard Blower Output - Cu. In. per Revolution   (5.840" represents modern designs)
 
Size Rotor Dia. Rotor Length Standard Helix
Output     CI/Rev
High-Helix
Output
2-71 5.778  4.875 136  
3-71 5.778 7.482 205 -
4-71 5.778 9.980 274 -
  5.840   290 290
6-71 5.778 14.975 411 472
  5.840   435 435
8-71 5.778 15.905 436 500
  5.840   461 461
10-71 5.778 17.000 466 536
  5.840   493 493
12-71 5.778 18.000 494 568
  5.840   522 522
14-71 5.778 19.000 521 600
  5.840   551 551
16-71 5.778 20.00 - -
  5.840   580 580
18-71 5.778 21.00 - -
  5.840   609 609
Effective Compression Ratio Chart
Static
Compress.
Ratio
Blower Boost Pressure (psi)
  2 4 6 8 10 12 14 16 18 20 22 24
6.0:1 6.8:1 7.6:1 8.4:1 9.3:1 10.1:1 10.9:1 11.7:1 12.5:1 13.3:1 14.2:1 15.0:1 15.8:1
6.5:1 7.4:1 8.3:1 9.2:1 10.0:1 10.9:1 11.8:1 12.7:1 13.6:1 14.5:1 15.3:1 16.2:1 17.1:1
7.0:1 8.0:1 8.9:1 9.9:1 10.8:1 11.8:1 12.7:1 13.7:1 14.6:1 15.6:1 16.5:1 17.5:1 18.4:1
7.5:1 8.5:1 9.5:1 10.6:1 11.6:1 12.8:1 13.6:1 14.6:1 15.7:1 16.7:1 17.7:1 18.7:1 19.7:1
8.0:1 9.1:1 10.2:1 11.3:1 12.4:1 13.4:1 14.5:1 15.6:1 16.7:1 17.8:1 18.9:1 20.0:1 21.1:1
8.5:1 9.7:1 10.8:1 12.0:1 13.1:1 14.3:1 15.4:1 16.6:1 17.8:1 18.9:1 20.1:1 21.2:1 22.4:1
9.0:1 10.2:1 11.4:1 12.7:1 13.9:1 15.1:1 16.3:1 17.6:1 18.8:1 20.0:1 21.2:1 22.5:1 23.7:1
9.5:1 10.8:1 12.1:1 13.4:1 14.7:1 16.0:1 17.31 18.5:1 19.8:1 21.1:1 22.4:1 23.7:1 25.0:1
10.0:1 11.4:1 12.7:1 14.1:1 15.4:1 16.8:1 18.2:1 19.5:1 20.9:1 22.21 23.6:1 25.0:1 26.3:1
10.5:1 11.9:1 13.4:1 14.8:1 16.2:1 17.6:1 19.1:1 20.5:1 21.9:1 23.41 24.8:1 26.21 27.6:1
11.0:1 12.5:1 14.0:1 15.5:1 17.0:1 18.5:1 20.0:1 21.5:1 23.0:1 24.51 26.0:1 27.51 29.0:1

Lysholm Screw  Cu. In. per Revolution
 
PSI 200-A 385
PSI 206-B 422
PSI 210-C 476
PSI 206-D 422
Whipple A980 601
Whipple R980 601
Whipple 305R 305

14-71 opening dimensions (Kobelco)

"Other " street / industrial

Size Rotor Dia. Rotor Length Output     CI/Rev  
"GMC" Straight 53 series (2 Lobe)
2-53    4.375 70 Bushings
3-53   6.5 104 "
4-53 Short   7.5 120 "
4-53 Long   8.7 139 "
"GMC" Straight 53 series (2 Lobe)
6-V53 Short   10.9 174 "
6-V53 Long   13.1 209 "
8-V53   15 330 "
"GMC" V 71 series (3 Lobe 30 deg)
6-V71 5.778 12 338 Ball Bearings
8-V71 5.778 15.9 448 "
Eaton (3 lobe 60 deg)
M-45   4.921 45 Ball/Needle bearing
M-62 tall 4.921 62 "
M-90   5.433 90 "
M-112 tall 5.386 112 "
B&M (3 lobe 60 deg)
144   8.7 144 Ball bearing
174     174 "
250     250 "
Weiand/Holley (2 Lobe Straight)
Pro 142   8.7 142 "
Pro 144   8.7 144 "
Pro 174     174 "
Pro 177     177 "
Pro 250     250 "
Pro 256     256 "
Camden
5 inch   5 80 "
7 inch   7 112 "
9 inch   9 144 "
12 inch   12 192 "
S.Co.T Italmeccanica Italian (2 lobe straight cast rotor)
4500cc   8.7 275 "
4000cc   8.7 275 "
S.Co.T- H&H Flatheads/U.S.A (2 lobe straight billet rotor)
    8.7 142 "
Street Blower boost @ aprox 6000 RPM
OD RATIO % -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35
                           
6-71 std                          
350 8.2 9.6 11.1 12.6 14.1 15.6 17.1 18.6 20.1 21.6 23.1 24.6 26.1
400 5.2 6.5 7.8 9.1 10.4 11.7 13.0 14.3 15.6 16.9 18.2 19.5 20.8
454 2.7 3.8 5.0 6.1 7.3 8.5 9.6 10.8 11.9 13.1 14.2 15.4 16.3
502 0.8 1.9 3 4.1 5.2 6.3 7.4 8.4 9.4 10.4 11.4 12.4 13.4
                           
8-71 std                          
350 10.7 12.4 14.0 15.5 17.1 18.7 20.3 21.9 23.5 25.1 26.7 28.3 29.9
400 7.6 9.0 10.3 11.7 13.2 14.6 16.0 17.3 18.7 20.1 21.5 22.9 24.3
454 5 6.2 7.4 8.6 9.9 11.1 12.3 13.5 14.7 16.0 17.2 18.4 19.6
502 3 4.2 5.3 6.4 7.5 8.6 9.7 10.8 12.0 13.1 14.2 15.3 16.4
550 1.5 2.5 3.5 4.5 5.6 6.6 7.6 8.6 9.6 10.6 11.6 12.6 13.6
                           
10-71 std                          
454 6.3 7.6 8.9 10.2 11.5 12.8 14.1 15.4 16.7 18.0 19.4 20.7 22.0
502 4.3 5.4 6.6 7.8 9.0 10.2 11.4 12.5 13.7 14.9 16.1 17.3 18.5
550 2.6 3.7 4.8 5.8 6.9 8.0 9.1 10.2 11.3 12.3 13.4 14.5 15.6
600 1.2 2.2 3.1 4.1 5.1 6.1 7.1 8.1 9.1 10.1 11.1 12.1 13.1
650 - 0.9 1.8 2.7 3.6 4.5 5.4 6.3 7.3 8.2 9.1 10.0 10.9
                           
12-71 std                          
454 7.5 8.9 10.3 11.7 13.1 14.5 15.9 17.2 18.6 20.0 21.4 22.8 24.2
502 5.4 6.7 7.9 9.2 10.4 11.7 12.9 14.2 15.4 16.7 18.0 19.3 20.6
550 3.6 4.8 5.9 7.1 8.2 9.4 10.5 11.7 12.8 14.0 15.1 16.2 17.3
600 2.1 3.2 4.2 5.3 6.3 7.4 8.4 9.5 10.5 11.6 12.6 13.6 14.6
650 0.8 1.8 2.8 3.7 4.7 5.7 6.6 7.6 8.6 9.6 10.5 11.4 12.3
                           
14-71 std                          
454 8.8 10.3 11.7 13.2 14.7 16.1 17.6 19.1 20.5 22.0 23.5 25.0 26.4
502 6.5 7.9 9.2 10.5 11.8 13.2 14.5 15.8 17.2 18.5 19.8 21.1 22.4
550 4.7 5.9 7.1 8.3 9.5 10.7 12.0 13.2 14.4 15.6 16.8 18.0 19.2
600 3.1 4.2 5.3 6.4 7.5 8.6 9.7 10.8 12.0 13.1 14.2 15.3 16.4
650 1.7 2.7 3.8 4.8 5.8 6.8 7.9 8.9 9.9 10.9 12.0 13.0 14.0
                           
14-71 HH