Only really for anyone feeling a bit geeky:
Working out the rpm of the alternator at the standard vts rev-limit.
Standard vts crank pulley - 138mm
Standard vts alternator pulley - 56mm
So the alternator turns 2.464 times to every crankshaft revolution, so at 7250 rev limit, the alternator is spinning at 17,866rpm.
If I was to use a 150mm Crank pulley, then the alternator would spin 2.679 times for every crankshaft revolution, meaning at 7250 rev limit the alternator is spinning at 19,420 (10% faster than oem) - add in a raised rev limit to 7,500 and the alternator is now spinning at 20,090rpm (13% more than oem)
So I want the alternator to spin at 5% less than oem at my max rpm (7500), so I want it to spin at (17,866 less 5% = 16,973rpm). 16,973/7500 = 2.2361. As a result I'll need an alternator pulley 2.2361 times smaller than the crank pulley = alternator pulley needs to be 66mm diamter (10mm more than oem or 18% larger)
