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Underdrive, light weight crank pulley

97AutoXVette

New member
Anyone on here running one of these??

I have been searching this topic a lot lately, and there are so many mixed reviews on whether or not they are safe to run. I cannot find a single thread where someone has suggested any issues because of them (after folks have been running them for years and many miles).

Running my light weight race battery, I would like this pulley for easier cold starts, less rotating mass, and less parasitic loss with the alternator and A/C pulleys.

Thanks!
 

torga

Drag Race Newbie
You do NOT want to run an undamped crank pulley, which are all lightweight pulleys. 4-cyl are incredibly shakey engines, so they need that harmonic balancer at the end so it doesn't shake itself apart. If you run an undamped, lightweight pulley, you will break something. It's not a matter of if, but when. Could be next week, could be years - it all depends on your driving style.

From my research, the best pulley for these cars is the FluidAmpr. It's a better pulley than OEM and it's damped across a wider RPM band than OEM. It's heavier than OEM, but because of its better damping properties, you still get less rotating mass and less parasitic loss. As for cold starts, just make sure your battery is up to the task by itself.
 

97AutoXVette

New member
You do NOT want to run an undamped crank pulley, which are all lightweight pulleys. 4-cyl are incredibly shakey engines, so they need that harmonic balancer at the end so it doesn't shake itself apart. If you run an undamped, lightweight pulley, you will break something. It's not a matter of if, but when. Could be next week, could be years - it all depends on your driving style.

From my research, the best pulley for these cars is the FluidAmpr. It's a better pulley than OEM and it's damped across a wider RPM band than OEM. It's heavier than OEM, but because of its better damping properties, you still get less rotating mass and less parasitic loss. As for cold starts, just make sure your battery is up to the task by itself.
Greatly appreciate this info. I have seen multiple folks also recommend the fluidampr. Will have to look into that more as well. Thanks!
 

Wascally Wabbit1

Ready to race!
Anyone on here running one of these??

I have been searching this topic a lot lately, and there are so many mixed reviews on whether or not they are safe to run. I cannot find a single thread where someone has suggested any issues because of them (after folks have been running them for years and many miles).

Running my light weight race battery, I would like this pulley for easier cold starts, less rotating mass, and less parasitic loss with the alternator and A/C pulleys.

Thanks!
Yep. I have also read tons of threads on the subject and have yet to see anyone actually break anything using them. Lots of gloom and doom but never heard anyone chime in with an actual issue. Like you said it's usually folks saying the exact opposite. I have heard issues with the underdrive pulleys though with AC and battery.
 

97AutoXVette

New member
Yep. I have also read tons of threads on the subject and have yet to see anyone actually break anything using them. Lots of gloom and doom but never heard anyone chime in with an actual issue. Like you said it's usually folks saying the exact opposite. I have heard issues with the underdrive pulleys though with AC and battery.
Same here... I actually could never find one thread/link to someone actually encountering issues after running one on their car. :iono:
 

Fast-R

Passed Driver's Ed
If you are looking for a crank pulley that does something positive, check out the Fluidampner crank pulley for our motors..
 

clownish

just clowning around
I’d say there’s some issue while installing one - can find unforeseen issues that were previously unknown - but not issues with actually using it.


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