pontiac455cars

I have a 4.25 pulley on a d-1,making about 9# at max rpm,I want to install a 3.85 to increase boost.Will I over spin the d-1?

ChevyChad

iTrader: (50)

what size crank pulley? What engine RPM? Your impeller RPM is the crank pulley diameter/ head unit diameter * engine rpm * step up ratio of the blower.

pontiac455cars

Chad,it is the exotic perfomance race kit.I beleive the crank is 7".Its the super dampner.It is a stock bottom end I spin to 6300 rpms.

BriancWS6

iTrader: (18)

Your no where near over spinning it with that setup. The D1SC max impeller rpm is 62,000. What your wanting to do will only be 51,324.

ChevyChad

iTrader: (50)

Well, if you have the standard 8 rib procharger crank pulley that attaches to the ATI superdamper with the 3 bolts, you most likely have a 7.65" crank pulley.. But as mentioned, even with the 7.65/ 3.85 combo, you would be at 51324.5 impeller RPM, which is only spinning it to 82.78% of its max potential. To max a D1SC out, you would need to use a 7.65/3.4 pulley combo, and spin the engine over 6700RPM.

EPP

iTrader: (22)

It is indeed the 7.65 diameter on the crank pulley. Bob