[Sixgunsled]

D1SC max propeller speed is 62,000 rpm. You need to know what your new redline will be at on the new engine set up. For example the stock redline is 6500rpm and after my engine build it was 7400rpm. I will be on 100% e85 with forged internals and secondary port injection fuel system. So to figure out what pulley I needed to max out the D1SC blower you divide the stock crank pulley size (7.48 if memory serves) by the pulley size you want to run (3.70) then multiply that by the procharger step up ratio (4.1) and multiply that by your engine redline (7400) and you get 61.336. That final number is the procharger propeller rpm. So that is the smallest pulley I can go on the D1SC. If you overspin the unit you just create excess heat and start to lose power. This formula came from procharger as I just called them yesterday and was going through the same process. I just need to upgrade to a larger head unit. The engine can support 1200 hp easily now.