I have a 1996 Miata with a JRSC. Current blower pulley is the JR 67.5mm, and the crank pulley is their BBK 150mm pulley. At the rev limit of 6900 rpm, that puts the blower speed at 15,318. I was thinking about changing to a 65mm blower pulley, which would spin the blower to around 15,870rpm. I have water injection that is not being taxed very much in the current configuration. I wanted to find out if spinning the M45 the extra 500rpm at that rev range would just excessively heat up the air and cause a loss in power, or would it give things a little more. I didn't want to increase the boost only to retard timing and dump a lot of water/methanol into the engine to compensate. Seems like taking two steps back to go one forward.

Thanks.

When I purchased my crank overlay pulley, I was told that 15,000 RPM was the maximum rating for the JRSC for CONTINUOUS use. Since no one actually runs the blower at that speed continuously in a street car, it's safe to exceed that speed for short periods of time. With the JRSC you can go from zero to top speed in just a few seconds, which is completely safe if your blower and engine are in good condition.