SN vs VS

[mfg]

When the Granatellis brought out their 'SN' version of the older design McCulloch 'VS' supercharger, what did Andy always say was the basic problem with the earlier unit...a problem which he said he corrected in the 'SN'?

[Gunslinger]

Andy said he found that the planetary balls were used without regard to consistency in size. The ones that were slightly larger in diameter carried excessive loads and failed early. He instituted tighter quality control inspections to make sure sets of planetary balls were identical in size before being installed or packed for sale.

[mfg]

True, but he spoke of another issue that he felt was most important. (Can't say more without giving it away!)

[GAWen]

As I recall there were some problems with the "VS" due to it's speed changing design, whereas the "SN" speed was directly proportional to engine speed.

[Gunslinger]

Andy also said that, along with the planetary ball issue with inconsistent diameters, they also found the supercharger's internal oil pump couldn't keep up with the rpm's the blower was spinning and had to be redesigned.

[mfg]

Andy also said that, along with the planetary ball issue with inconsistent diameters, they also found the supercharger's internal oil pump couldn't keep up with the rpm's the blower was spinning and had to be redesigned.

That's it!.....The oil pump issue...Andy said the planetary drive would be starved of lubricant at high RPM....when it needed it the most. He went to a stronger spring, lighter oil pump plunger, and a different 'cam' profile.

[brad]

New oil pumps from Paradise wheels are an improved design, with a larger piston diameter for more volume and pressure.