Have Paxton SN93... What pulley for 8Lbs?

[pd411]

Hey all new to this forum... Just curious what Underdrive pulley do i need in order to bring it up to 8Lbs of boost? I currently have the factory 4Lb pulley on it. Also where can i buy this pulley? Btw its for 94 LT1.


Thanks,
Eric

[Ghost88]

You will need a high output impeller and a 3.75 pulley and maybe a 6.5 crank pulley. You will need a power pipe and if you go over 7lbs you will need a Bypass valve. You can buy the pulleys from C.U.N.D.N Racing if you want the bigger impeller you can send your head unit to them. The Bosch Bypass valve you can buy from Summit Racing. I just notice you have a Chevy. I had one of those.

[pavement pounde]

Do not overspin the supercharger, 8 psi is propably to much, check the other post about max. impellerspeed, the LT1 does not have a powerpipe.
You might upgrade to a improved impeller from CUND or any other, check Ebay, also for different size pullies.

[winfred]

heres a handy calculator for impeller speed http://www.928motorsports.com/servic...tingpulley.php (4.4 ratio on the SN)

i am spinning my sn-92 at 41k and getting 7# with a 2.8 inline 6 with the stock impeller, a larger engine is going to have less boost, the health of the unit will suffer if spun much faster then 41k especially if you are not running a lube cooler on the supercharger, i think the accepted max rpm is 38k without a cooler 41k with

[pavement pounde]

Winfred is right.
You can also do the math yourself:

Impeller Speed Calculations:

Crank Dia.
----------- x RPM x Blower Ratio = Impeller Speed
Blower Dia.

SN stepup blower ratio = 4.44
This site has a lot of pulleys: http://www.superchargersonline.com/p...s_crank_pulley

http://www.superchargersonline.com/s...ve_pulleys.asp

http://www.aspracing.com/frame.htm

[pd411]

Hmmm so what would you guys suggest? From what im reading if i want to go anymore boost with the sn93 im going to have to switch the impeller aswell? Also does anyone know where i can get a power pipe for the LT1?

[pavement pounde]

Have you done the math ? can you go with a smaller pulley ?
The improofed impeller would give you 1 psi extra, that's a fact.

[pd411]

Have you done the math ? can you go with a smaller pulley ?
The improofed impeller would give you 1 psi extra, that's a fact.

No I cannot go with a smaller pulley sorry i was kinda jumping the gun before i did the math.... I would be way over the impeller limit on the blower... So i suppose id have to find otherways to make more boost with what i have. Any suggestions?

[pavement pounde]

http://cgi.ebay.com/ebaymotors/High-...item3a50570368
Do not sell your impeller to him, he sells the stock impellers for way more on ebay.
On my 454 engine the improofed impeller gave me a gain of 1 psi, yours is smaller so I gues 1- 1.5 psi.
Also try to smooth the air tubes as much as possible and use the biggest filter and coolest air.
No sharp bents in the airpipes.
Also be sure you do not have beltslip or any airleaks.

[winfred]

I didn't know the stock impeller was worth enough to try and get more, thanks for the heads up as I am going to get one sooner or later

http://cgi.ebay.com/ebaymotors/High-...item3a50570368
Do not sell your impeller to him, he sells the stock impellers for way more on ebay.

[pavement pounde]

You can trade in your stock impeller for $35 and then he sells it for: http://cgi.ebay.com/ebaymotors/Paxto...Q5fAccessories

Better sell it yourself and try to get more.

[winfred]

Guess the trick is does he actually sell em or do they hang around forever, still worth a shot, have his expensive one make mine look better

[pavement pounde]

:D:D