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Old 03-05-2014, 11:42 AM   #59
stugray
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Join Date: Sep 2013
Drives: 2013 GBS BRZ Limited
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Quote:
Originally Posted by tennisfreak View Post
This thread should be about pulleys and I have not seen a post in the last 4-3 pages about pulleys.
I'll chime in since I have debated this issue repeatedly on other threads:

1- unless the pulleys underdrive the accessories (Water pump, Alt., & A/C), then they cannot make more HP.

2 - Even if you replace the pulleys "because it gives you a lower mass rotating assembly" then the pulleys are the LAST part you should worry about.
Being near the cneter of rotation, the pulleys contribute the least to the rotational inertia of the rotating assembly. (the drive belt probably contributes more)
If you want to reduce rotating mass, then go ahead and replace the pulleys, but a lightened flywheel & clutch assembly makes a MUCH bigger difference.

3 - There is still a debate about the pulley's contribution to balance on these engines. If you build a racing boxer engine, you pay extra to have the rotating mass balanced. Were these engines balanced at the factory? (no-one knows - at least on this forum). IF the engine was balanced, changing the pulley without a rebalance is a bad idea.

4 - If you want to argue - "But lighter pulleys reduce the overall weight of the car by pounds". If you believe that so strongly, then take the wheel balance weights off your wheels. That is a few pounds of unsprung weight....
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