I need help with a pulley size selection for desired boost

[MaYHeM]

Hello Guys,

My buddy purchased a Novi 2000 supercharger kit for a 86-93 Mustang but the kit came with a 8" crank pulley instead of the 7" we normally see. My question is just to get everyone's input on what they think would work or not work for his setup. This is on a mostly stock 302 with exhaust, Ported GT-40 Upper/Lower Intake, 60 Lbs Injectors, Billet fuel rails, Fuel Pressure Regulator, Fuel system upgrade (Wiring and front lines, 255 Pump), Holley TBody, and Pro-M MAF. He plans to get a chip and the car dyno tuned and not use a FMU.

He's trying to avoid buying a 7" crank pulley if he can get away with it since they are like around $450.00. I wanted to see what you guys think if he ran the 8" crank pulley and the largest blower pulley (Say 4.25") what boost numbers do you think he would see if he kept it below 6K RPM (Shift Say 5500 on Manual Trans). I was thinking with a moderate tune and the timing kept low he would maybe see around 12-15 psi and have to be easy on the car till he gets his next short block done. (He's planning a 4-bolt short block but wants to run this till like next summer)

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Any input would be greatly appreciated. I run a Novi 2K setup on a 347 using the 7" crank and 3.25" Blower pulley with the power by-pass kit on a AEM Standalone blowing to atmosphere. I have H/C/I plus+ and I see 9psi with a 10-12 psi pulley but you can't compare the setups. Thanks for any help! Sorry it's been awhile since I've been back on here. :think:

[novi306]

Look in general tech there is a blower spreadsheet in there for a download

[MaYHeM]

Thanks for the response! The spreadsheet is a great tool but I noticed it only states you can change the crank pulley diameter or blower step-up ratio that's in Red. It doesn't have the pulley sizes I'm questioning (Like 4.00 - 4.25) and it doesn't have 3.25 that I run on my setup either. I also noticed if you change the pulley size it recalc's the math in the column so I'm wondering if the output information is correct when you change one of the pulley sizes from like 3.33 to 4.25. It seems like it's changing correctly when comparing the differences. Man it would be nice if someone went a little further with this spreadsheet on estimated boost levels with given H/C/I data even if it would only be estimated or close in it's output.