Underdrive crank pulley VS. coolant temp/water pump speed ??

[GS70350]

Hey guys, when i first purchased my car, i found that it has a aluminum underdrive crank pulley, and all the other pulleys are stock. i have read that the pulley gives no gains in performance over stock. i would guess it gives about 5 hundreths of a second perhaps? sounds like a reasonable number. anyways, i notice that my alternator spins slow enough that the lights dim way down till you rev it to about 1K rpm. this tells me the alt and most likely the water pump are spinning too slow for my liking. my coolant temperatures are about 170 or so, with the high speed fan running, no AC on, and no radiator baffles or nothin. sometimes it will drop to 160 if im movin fast enough. NOW< what kind of a increase am i experiencing in coolant temperature, due to the slower spinning water pump? is there some way i can get a overdrve water pump pulley to spin the water pump at stock or faster speeds? if anyone has any numbers that they might have gotten from their use of the pulley, please let me know. thanks guys

 

[Dean]

Probably so, but at that point, why? If it were mine, I would pull the u/d pulley and put on a stock one... actually, I would put on a RJC stock style aluminum pulley.

 

[bruce]

Originally posted by GS70350
Hey guys, when i first purchased my car, i found that it has a aluminum underdrive crank pulley, and all the other pulleys are stock

Get a stock crank pulley.
Then an ATR overdrive water pump pulley,
and then a smaller ALternator pulley.

Works well...

 

[GS70350]

I will probably end up buying a stock pulley, but i would like to know how much of a difference in coolant temp the underdrive pulley creates. id like to know this first to see if its worth it to me or not to get a stocker when my budget is the way it is.

Anyone have any Temp* numbers before and after or any good guesses? if its 10 degrees or so, im removin it.

 

[Chris McDade]

I've been running just the under drive after market pully for years now with no problems.

 

[bruce]

Originally posted by GS70350
I will probably end up buying a stock pulley, but i would like to know how much of a difference in coolant temp the underdrive pulley creates. id like to know this first to see if its worth it to me or not to get a stocker when my budget is the way it is.
Anyone have any Temp* numbers before and after or any good guesses? if its 10 degrees or so, im removin it.

I doubt you'll see any real difference.
BUT,
the water pump speed dictates the coolant pressure in the block and cylinder heads, the higher the better, since it reduces the chance of localized overheating, within the heads.
Spinning the alternator faster means you always have enough voltage for the ignition system the injectors, and fuel pump if you have to change why not do it right once, is my motto.