• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Fiesta ST Forum and Fiesta ST community dedicated to Fiesta ST owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the Fiesta ST Forum today!


Whoosh overdriven water pump pulley

Messages
254
Likes
201
Location
none
#2
I did install a PumaSpeed version. No difference in butt-feel. Cooling took no hit(I live in a mild climate though). The install was easy. 4 bolts and a serpentine belt.
 


OP
F
Messages
156
Likes
126
Location
Sebastian, FL, USA
Thread Starter #3
I did install a PumaSpeed version. No difference in butt-feel. Cooling took no hit(I live in a mild climate though). The install was easy. 4 bolts and a serpentine belt.
Cool thanks. This one spins the water pump faster so it should help cooling with the upgraded radiator. Still less weight. Do you know what the torque specs for the pulley was?
 


Messages
180
Likes
188
Location
Atlanta
#4
this is interesting to me because on other/older platforms, ideally you want a bigger radiator and slightly slower movement of the coolant through it, to allow more effective cooling. on other platforms, actually underdrive it to achieve that goal. From that POV, seem spinning the pump faster would be superfluous with a radiator upgrade.

For context, recently did this with an RS - bigger radiator with a lower temp thermostat - car is utterly rock solid on temps. no changes to pulley.
 


OP
F
Messages
156
Likes
126
Location
Sebastian, FL, USA
Thread Starter #5
this is interesting to me because on other/older platforms, ideally you want a bigger radiator and slightly slower movement of the coolant through it, to allow more effective cooling. on other platforms, actually underdrive it to achieve that goal. From that POV, seem spinning the pump faster would be superfluous with a radiator upgrade.

For context, recently did this with an RS - bigger radiator with a lower temp thermostat - car is utterly rock solid on temps. no changes to pulley.
Nice. Yea it is an interesting topic I was looking into it aswell. Svt design and fab makes a underdriven pulley for the fiesta. I watched a video a video that sold me on the over driven pulley. He was stating especially with a bigger then factory radiator slower moving coolant will cause dead spots in the radiator thus reducing the cooling capacity and may cause warm spots in the motor. Faster moving coolant flow would prevent this.
 


Messages
987
Likes
1,589
Location
San Francisco Bay Area
#6
The only real risk I see with overdriving is that especially with an upgraded turbo (which shifts the powerband to high RPM), you could start to get cavitation in certain situations which will f*** a pump pretty good over time.

The rotating inertia of a small component like the water pump pulley is usually negligible. Underdrive pullies are mainly useful when it comes to heavily cammed engines operating well above the factory redline, where the previously mentioned problem of cavitation can occur. You may get a small amount of reduced pumping loss, but it’s not going to make a large difference, at least not on a modern engine

You don’t really get increased pumping by just spinning the water pump faster. Because of the large range of speeds, the water pump (like the oil pump) reaches max flow at less than max RPM (ideally you want max cooling before peak torque when the engine is actually stressed the hardest) and a relief valve limits the water pressure.

The only way to actually increase flow through the engine is to increase the water pressure (relief valve) forcing flow through the block, but that can do funky things to the flow path.
 




Top