Need to identify pulleys on my car

[jnavin]

I recently purchased my 95 GT. I am replacing my alternator, so I figured I might as well put pulleys on it as well. I decided on March Pulleys. Well when I get to pulling the alternator I see that the crankshaft, waterpump, and aternator pulleys are all polished aluminum, so they are obviously after market...Well I measured them and the diameters are 2 3/4" for the alternator, 5 3/4" for the waterpump, and 5" for the crankshaft. The pulleys March sells are 4.375" for the crankshaft, 5.5" for the waterpump, and 2 inches for the alternator.

I was just going to go ahead and use these pulleys and save the money of buying new ones, but the thing I don't understand is why my alternator pulley is
3", thats even bigger than stock. Isn't this robbing me of power. All input would be appreciated

 

[Fox8950]

3?? thought you said new kit comes with 2" (which is what I thought stock was). Smaller the pulley = Spins faster so a huge pulley like 3" on an alt. would undercharge ya big time.

 

[jnavin]

Thats what I was thinking, which is why I can't understand any good reason for putting a 3" alternator pulley on. So I guess the conclusion is to get new pulleys?

 

[69PaleHorse]

Sounds like what you have is an underdrive pulley set, which is a fairly common mod. IIRC, the idea of an underdrive set is to reduce how quickly accessories spin, thus reducing the amount of drag/parasitic loss involved in spinning them, this results in freeing up a little more power.

Frankly, if you are not seeing problems with cooling or charging, I would leave them on and put the money you were going to spend on March pulleys toward something else.

 

[samickguy15]

.

Sounds like what you have is an underdrive pulley set, which is a fairly common mod. IIRC, the idea of an underdrive set is to reduce how quickly accessories spin, thus reducing the amount of drag/parasitic loss involved in spinning them, this results in freeing up a little more power.

Frankly, if you are not seeing problems with cooling or charging, I would leave them on and put the money you were going to spend on March pulleys toward something else.

X2 here...