- Nov 18, 2012
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Gail, you give me too much credit.... Im still learning, just like many following this thread Thank you for your time helping us out.
Im still trying to figure that one out, they are high helix rotors designed to pull air from the back of the case and push the air forward a bit before dumping it out the bottom, but there are also 8-71 blowers that are 3 lobe high helix rotors that are draw thru type. Question is would the eaton rotors work as a draw thru supercharger if the case was altered? Ive been trying to look up the twist on the 8-71 high helix rotors but havent found it yet....still searching...I have heard them referred as roots blowers over the years, but I looked it up, and this is wrong. They are twin screw. My mistake.
I seem to be a little late to the party. I didn't use any fancy math, just trial and error. The radii on the lobes needs to be smaller than the radii in the valleys. The difference in radii depends on the clearance you want. I made by rotors with a .005 clearance so the outside diameter was .010 smaller than the bore and the radius on the nose was .005 smaller than the radius in the valley. The perfect fit is so no rotating parts touch so the pair get installed and geared together. Then they get blued and checked for wear spots. Alot of hand work to get them tight but not touching.Tring to figure out how to model the hypocycloidal and epicycloidal curves of a supercharger rotor in alibre cad. This is really making me pull my hair out!
Steve H, have you managed this with your model blower??
Im trying to design a 3 lobe rotor for a blower with a 71ish cid displacement...
From thier description of the housing...If you look at pictures 6, 8, and 9 in the gallery of this link http://www.superchevy.com/how-to/0610ch-magnuson-superchargers/parts-cost.html it looks like the only function of the back side of the housing is for the boost bypass valve. It looks to me that the air flow goes straight down, from what I can see in those pics.
This site reckons the angle for a 6-71 is 30 degrees. I guess the 8-71 would be similar.Ive been trying to look up the twist on the 8-71 high helix rotors but havent found it yet....still searching...