question on SN series

[sic89gt]

ive been looking at getting a SN series supercharger. the guy that has it said it is a little hard to turn it by hand. Is the normal for these?

[Michael]

Welcome to the forum.

An SN that's hard to turn by hand is generally OK. Notching or catching on the other hand is not. That would indicate worn bearing races and/or drive balls.

[sic89gt]

Thanks. I'm really glad I found this site. I've learned a lot from just reading a bunch of posts over night.the guy had it on his car and said it worked perfect. But when I talked to him the other day he had said it was a little tough to turn by hand so I became a little sceptical.


Another question I had was about the smog pump pully/delete pully. I have a 89 mustang with no pump or pully. Is it safe or ok to run the s/c without it there or would I need to get that delete pully?

Also would 24lb inj be enough to run it? The kit comes with a fmu aswell. It will be ran on a 306, bcam, gt40 intakes, 73MM massair, 70MM BBK tb, stock heads and under drive pullys.

[steel1]

You could check the inch pounds on the pulley nut, I think it should be around 25-35 in.lbs. (someone on here will verify). O.K. to run without smog / pulley. If the FMU is calibrated for the 24lbs. injectors it will be O.K. Make sure you upgrade your fuel pump, I'm going 225lph in tank.

[sic89gt]

i already have a 255lph in my tank. im not sure what what the fmu is set at.. how would i check? and if its not can it be redone for 24lb?


BTW: its a SN92

[steel1]

The discs inside the fmu are what calibrates it. I believe you would need 8:1 ratio disc, my fmu is 6:1 for 30lb. injectors. You could measure the disc in yours to determine ratio, here's a link that should help.
http://www.superchargersonline.com/p...2=fmu_cal_disk