Ok, so you want to run the best hardware available, racing parts here, there everywhere. But then you realize just why their racing parts; they just don't perform well on a daily driven vehicle at cruising speeds. You know, like those extremely low profile tires designed to corner like a train on rails, then you realize that there isn't any potholes on train tracks and your wicked exspensive wheels are getting pounded to death for the profile.
The same goes for the racing dampeners sold by ATI, yeah. I know that there is a street damper, but the race part protects at higher HP and speed which is why we picked it. Who cares about power steering and AC? Just give me that underdriven pulley/ damper race part, remember. Then you realize that headlights and blower motors and fuel pumps and nitrous solenoids etc. require lots of power from the charging system which by description has been underdriven to a FAULT! I mean, this pulley is so small that your lucky to run a race car and forget about a sound system.
So I did some measuring and got the low down on the factory drive ratio and the ATI ratio.
The factory ratio as measured exactly is 2.52:1
If the ATI damper is used it will be 1.3:1
The altenator speed is nearly cut in half! But it is even worse for the actual charging system as peak amps is reduced by as much as 75% because of slow armature speeds.




OK, so how to correct this is simple, reduce the diameter of the driven (alt) pulley. Not very good option from Honda as I have not found a smaller one yet. Aftermarket stuff is going in the other direction (slower speeds); so wwhat can you do to keep that excellent ATI piece on your street ride? Suffer with a limited charging system and fry the battery out, or dig deeper to find the right compromise. Because, after all it is a good idea to slow things down a little but 50% is too much. I found a site called Quick Start Altenators and searched for 4 ribbed pulleys and found a couple that measured 2". This would allow the drive ratio to be reduced to a newer 1.7:1 from the factory 2.52:1, not bad at all. I am searching for the B series altenators in this article and am not sure about othe motor ratios or compatability. I found a pulley from a Ford altenator (96 Probe) here locally and it matched perfect and is 2" with 4 ribs. The shaft diameter was identical and offsets too. This simple one bolt upgrade will slightly increase alteneator speeds so that the daily driven dragon can support her accesories, without truly comprimising any high rpm HP. Salvage yards usually have piles of cores around and are willing to sell you a pulley if you like. Just ask or search for yourself to get the satisfaction from the journey to making race parts work on the street.

 

May I ask, which vehicle was this done on?

 

This is a B20B in a 94 DelSol.