I asked JR Granatelli if he had any information about the different impellers used in the SN series units. Below is the email I received. Interesting information, thought I would share with you folks.
Quote:
Originally Posted by Buck-Strickland
Dear Mr. Granatelli,
Sorry to bother you, but I was hoping with your knowledge of the Ball Drive SN series Paxton superchargers you might be able to shed some light on an information gap. It appears that there were two versions of the impellers for the SN series, specifically the SN 2000 and SN 2000HO the later which had a different impeller which apparently produced more boost (2-3psi.) The information gap revolves around the amount of CFM the HO impeller could produce. I was wondering if you have any solid CFM numbers between the standard and HO impeller that you could share with the forum. Any information on the two impellers would be of interest. Unconfirmed information puts the standard impeller at 850cfm and the HO at 1,100cfm, followed by the VR4 conversion at 1,400cfm. Any information in this matter would be greatly appreciated. There are those of us who really want to keep these units around and this Superchargerhelp.com forum has become an excellent repository of history and information.
Thank you,
Mike
The standard impeller was rated at - 800 cfm @10psi (277 H20) @ 42,000 impeller speed - At that flow and pressure it supported 500hp.
The intended use of the SN60, SN89, SN92 and SN93 was 560 cfm @ 6psi (166.2 H20) @ 37,500 impeller speed – These blowers were later called the SN-2000 in 1997 to signify things to come in the new millennium. At that flow and pressure it supported 350hp.
The HO impeller was no more than a standard impeller scalloped on the ends like a scoop. By modifying the impeller in this manner we were able to achieve the following: 800 cfm @ 8.5psi (235.45 H20) (500hp) @ 38,500 impeller speed & 925 cfm @ 10psi (277 H20) (575hp) 42,000 impeller speed. Additionally, By making the impeller lighter and increasing airflow at cruise, case temperatures dropped by 75 degrees.
The VR4 went from a 3.5 to 4.00” inlet and moved tons of air down low – it was not about peak power with the VR4 it was about average power, or should I say how fast it would ramp and make power based on flow and pressure.
VR4 flowed:
5psi – 560 cfm
6psi – 616 cfm
7psi – 672 cfm
8psi – 731 cfm
9psi – 785 cfm
10psi – 841 cfm
11psi – 901 cfm
12psi – 957 cfm
13psi – 1015 cfm
14psi – 1073 cfm
15psi – 1120 cfm - @ 44,000 Impeller speed
The Novi-2000 is rated at 1650cfm @ 15 psi
The most desirable supercharger offered by Paxton was the Novi-GSS. We only made 50. The Novi-GSS produced 20psi at 1800cfm. It had a 10 to 1 internal step up with 3 forward driving helical sun gears in concert driving the center shaft output shaft which was connected to the impeller. It turned 75,000 rpm. I was one bam mother. My Uncle Vince Granatelli decided it was too much money to mass produce.
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Originally Posted by Granatelli
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